Detection of metals in hair and process for detecting undesirable colouring residues and set for implementing the process

Abstract

Process and kit for detecting the presence of at least one metal, in particular copper, in hair fibres, comprising bringing the hair fibres into contact with a test composition comprising, in aqueous medium at alkaline pH, at least one ammonium salt, and hydrogen peroxide, so as to enable the generation of a possible evolution of dioxygen gas at the surface of the hair fibres, the presence of such an evolution of gas revealing the presence of said metal in the hair fibres. In addition, a process and kit is disclosed for revealing undesirable colouring residues in hair fibres, by bringing, in a container, sampled hair fibres at a temperature greater than ambient temperature into contact with either (a) an aqueous, alkaline composition comprising 2-15 weight% of an oxidizing agent, or (b) an extraction solvent for observing a possible colouring thereof.

Description

[0001] Description

[0002] Title: Detection of metals in hair and process for detecting undesirable colouring residues and set for implementing the process

[0003] Technical field

[0004] The present invention relates to the field of hair treatments.

[0005] According to a first of its aspects, the invention relates to compositions and processes for revealing the presence within the hair of undesirable compounds capable of affecting a treatment for colouring, bleaching or shaping the head of hair. According to a second of its aspects, the invention relates to a process for revealing the presence within the hair of undesirable compounds capable of affecting a treatment for colouring or bleaching the head of hair.

[0006] Prior art

[0007] Some swimming pool water disinfection systems use metals such as copper, and swimmers’ hair can gradually become laden with copper, which can react with compounds present in colouring or bleaching compositions or in compositions for permanently modifying the shape of the head of hair, leading to a result which does not correspond to expectations. In particular, too much copper in the hair can lead in certain situations to a greenish colouring when a bleaching product is applied to said hair.

[0008] In addition, the presence in the hair of metals such as copper tends to weaken the hair, especially if the hair is exposed to oxidizing agents, such as those conventionally used for oxidation dyeing, permanent shaping or bleaching treatments. This weakening can lead to a loss of the cosmetic surface properties of the fibres, a loss of mechanical properties or even premature breakage. In addition, for certain oxidation dyeing operations, the presence of metals, most particularly copper, can modify the proportions of dyes fixed in the hair and the colour obtained is not the one expected.

[0009] It is therefore essential to be able to detect the presence of these metals in order to avoid such detrimental effects.

[0010] It is thus conventional teaching in hairdressing schools to carry out a preliminary test on a lock of hair in order to verify the result of the subsequent application of a hair treatment product. To do this, before applying the product in question to the entire head of hair, the product is applied in a small amount only to an isolated lock in order to verify that the result obtained does indeed correspond to what is expected.

[0011] This practice takes a considerable amount of time since it requires leaving the product to act on the lock used for the test, conventionally for about twenty minutes.

[0012] In addition, the product applied to the lock for the test usually comes from the same packaging as that used to treat the entire head of hair, such that if the result does not correspond to the expected one, the rest of the product contained in the opened packaging will not be able to be applied and will be lost unless it is able to be quickly used on another person.

[0013] Lastly, this practice does not make it possible to easily identify the cause of an undesirable result. In addition, some dyes leave behind colouring residues in the hair that can negatively affect the result of a subsequent colouring or bleaching treatment.

[0014] These undesirable colouring residues may originate from a natural colouring. A natural colouring is a colouring formulated on the basis of plants and natural active ingredients, such as henna, Eclipta prostrata, indigo, safflower, woad or fruit powders, for example Indian gooseberry.

[0015] The dyes having residues that will be problematic may also originate from the prior application of direct dyeing products, for example azo dyes, or even from certain oxidation dyeing products which lead to the formation of particularly chromatic azomethine dyes.

[0016] It is thus conventional teaching in hairdressing schools to carry out a preliminary test on a lock of hair in order to verify the result of the subsequent application of a hair treatment product. To do this, before applying the product considered for use on the entire head of hair, the product is employed in a small amount only on an isolated lock in order to verify that the result obtained does indeed correspond to what is expected.

[0017] This practice takes a considerable amount of time since it requires leaving the product to act on the lock used for the test, conventionally for about twenty minutes.

[0018] In addition, the product applied to the lock for the test usually comes from the same packaging as that used to treat the entire head of hair, such that if the result does not correspond to that expected, the rest of the product contained in the opened packaging will not be able to be applied and will be lost unless it is able to be quickly used on another person. An alternative consists in applying a bleaching product under conventional conditions of use, which allows the hairdresser to identify certain colouring residues by visualizing these dyes against a lit background. This alternative usually requires an even longer testing time, of the order of 50 minutes.

[0019] Disclosure of the invention

[0020] Thus, there is a need to facilitate the diagnosis of the presence of undesirable compounds in hair fibres and to identify them.

[0021] There is also an interest in accelerating the demonstration of potential undesirable effects, prior to the application of a colouring or bleaching or a shape modifying product.

[0022] There is furthermore a need to facilitate the diagnosis of the presence of undesirable compounds in hair fibres and to identify them.

[0023] There is also an interest in accelerating the demonstration of potential undesirable effects, prior to the application of a colouring or bleaching to the hair.

[0024] Summary of the invention

[0025] Detection of metals in the hair

[0026] According to a first aspect, the invention relates to a composition, to a process and to a set of devices for the detection of metals in hair fibres.

[0027] According to this first aspect, the invention provides a process for detecting the presence of at least one metal, in particular copper, in hair fibres, the detection process comprising bringing the hair fibres into contact with a test composition so as to enable the generation of a possible evolution of dioxygen gas at the surface of the hair fibres, the presence of such an evolution of gas revealing the presence of said metal in the hair fibres, the test composition comprising, in aqueous medium at alkaline pH, at least one ammonium salt, and hydrogen peroxide.

[0028] The presence of the ammonium salt makes it possible to achieve an evolution of dioxygen which is more or less significant depending on the metal content.

[0029] Preferably, the composition comprises at least one polyol. The presence of the polyol makes it possible to increase the amplitude of variation in the bubbling depending on the metal content. The preferred pH range of the composition may depend on the polyol content. The presence of polyol may make it possible to operate at a lower pH.

[0030] The composition may have, in particular in the presence of polyol, a pH of greater than or equal to 9.4, better still greater than or equal to 9.6.

[0031] In one example that gives good results, the composition comprises a polyol and its pH is 9.8.

[0032] The composition may have a pH of greater than or equal to 10, better still strictly greater than 10, in particular greater than or equal to 10.2. A high pH tends to increase the amount of dioxygen produced for a given metal content in the hair.

[0033] Preferably, the test composition comprises, in aqueous medium at alkaline pH, at least one ammonium salt, hydrogen peroxide, and at least one polyol.

[0034] The detection process may comprise a preliminary step of preparing the test composition, in particular extemporaneously.

[0035] This process is particularly easy to use. It makes it possible to quickly identify the presence of said metal in the fibres tested.

[0036] The detection process may comprise the evaluation or quantification of the dioxygen produced, in order to deduce therefrom the amount of metal present in the hair fibres, the amount of dioxygen evolved being related to the amount of metal present. In particular, the test composition advantageously makes it possible to rapidly detect, typically in less than 7 minutes, the presence of metals, in particular copper, in the hair, by the simple observation of an evolution of dioxygen gas, resulting from the decomposition of the hydrogen peroxide.

[0037] This makes it possible not only to detect the presence of a metal but also to quantify the content thereof in said hair, by evaluating or measuring the amount of dioxygen evolved.

[0038] Optionally, the process comprises a comparison of the amount of dioxygen produced or of the corresponding amount of metal with a reference value or scale, in particular the comparison of the amount of metal with a threshold value beyond which the amount of metal present in the hair fibres is liable to significantly impair a subsequent treatment, in particular colouring treatment, of said hair fibres, this threshold value preferably being chosen between 40 ppm and 200 ppm, in particular between 50 and 100 ppm. Several threshold values may be predetermined, each threshold value being indicative of the degree of likely impairment of a subsequent treatment of colouring, bleaching or modifying the shape of said hair fibres.

[0039] For example, a first threshold value of 50 ppm may indicate a medium probability of impairment, and a second, higher, threshold value, for example 100 ppm, indicates a high probability of impairment of the result.

[0040] The detection process may be performed on a sample of hair fibres with a relatively small amount of fibres, in particular less than 100 mg.

[0041] The process may comprise a preliminary step of sampling hair fibres, in particular by means of a hair fibre sampling wand, said sample then being brought into contact with the test composition.

[0042] The detection process according to the invention may comprise the following successive steps:

[0043] 1) taking a sample of hair fibres, in particular by means of a sampling wand;

[0044] 2) providing a test composition according to the invention, or providing compounds and / or solutions that, by mixing, enable such a test composition to be produced;

[0045] 3) bringing the test composition into contact with the hair fibres to be tested, in particular at ambient temperature, for at least 2 minutes and preferably at most 7 minutes, more preferably at most 5 minutes, so as to place said hair fibres under conditions for interacting with the test composition, the presence of a metal within the hair fibres being reflected by the formation of bubbles at the hair fibres and possibly by the rising of the bubbles to the surface of the composition.

[0046] The sampling of the hair fibres makes it possible to avoid carrying out the test directly on the client’s hair. This makes it possible to improve client comfort but also to avoid carrying out the test on a sample of hair fibres comprising more fibres than necessary.

[0047] In particular, the invention allows the hairdresser to quickly determine the condition of the hair of their client, the implementation of the process generally not taking longer than 10 minutes, or even 5 minutes.

[0048] The sample preferably comprises between 10 mg and 100 mg of hair fibres.

[0049] The provision of the test composition may comprise the implementation of the preparation step. The step of, in particular extemporaneous, preparation may comprise mixing a first solution comprising at least one ammonium salt with a second aqueous hydrogen peroxide solution in which at least one polyol has preferably been incorporated.

[0050] In an alternative embodiment, the preparation step may comprise mixing a first solution comprising at least one ammonium salt and preferably at least one polyol with a second solution being an aqueous hydrogen peroxide solution.

[0051] Preferably, said at least one polyol, when present, is already mixed with the aqueous hydrogen peroxide solution within the second composition available to the end user.

[0052] Conventionally, an aqueous hydrogen peroxide solution is called aqueous hydrogen peroxide. Thus, the second solution may be an aqueous hydrogen peroxide solution, for example a 20 vol to 60 vol aqueous hydrogen peroxide solution to which at least one polyol is preferably added. In particular, the second solution may consist of 70%- 90% by volume of 33 vol aqueous hydrogen peroxide solution, and the balance of polyol.

[0053] The preparation step may comprise mixing the first solution of basic pH comprising water and at least one ammonium salt in a concentration of between 0.5 g and 0.9 g per 100 mL of solution with the second solution composed for example of more than 10%, for example about 20%, by volume of polyol and the balance to 100% of aqueous hydrogen peroxide solution, for example an aqueous hydrogen peroxide solution with a titre of between 30 and 40 vol, the ratio by volume of the first solution to the second solution in the test composition being between 0.4 and 1.

[0054] The preparation step may comprise adjusting the pH of the composition, in particular of the first solution, by adding aqueous ammonia.

[0055] In step 3), the hair fibres may be brought into contact with an amount of test composition of between 5 mL and 15 mL, such an amount being well suited to a mass of hair fibres of between 10 mg and 100 mg.

[0056] In some embodiments of the invention, the test composition is prepared in contact with the hair fibres.

[0057] In other words, the provision of the composition may be carried out in parallel with the contacting with the hair fibres, steps 2) and 3) of the process then being carried out simultaneously.

[0058] In particular, the process may comprise contacting of the hair fibres with a first, alkaline solution and then addition of a second, hydrogen peroxide solution. The first solution may further comprise at least one ammonium salt. The second solution may further comprise at least one polyol.

[0059] In the event of positive detection of the presence of a metal, a remediation composition may be applied to the hair fibres so as to remove and / or isolate the detected metal.

[0060] This remediation composition is for example a hair composition containing at least one remediation active ingredient, for example a shampoo, a colouring, a bleaching, a product intended to produce permanent waving or a care for the hair.

[0061] Optionally, after application of the remediation composition, a new test on the hair fibres treated with the remediation composition is carried out, making it possible to evaluate the action of the remediation composition on the metal content of the head of hair.

[0062] In addition, the detection process may comprise backlighting of the test composition during the possible evolution of gas.

[0063] The backlighting makes it possible to better distinguish the bubbles forming at the surface of the hair fibres and possibly the rising thereof towards the surface of the test composition. Such backlighting improves the accuracy of the evaluation of the test result. It may be carried out from behind the vial containing the test composition or better still from below the vial. To ensure good visibility of the bubbles, it is also possible to place the vial in front of a black background and illuminate it from below.

[0064] Test composition

[0065] An alkaline pH is a pH strictly above 7. The pH of the test composition is determined at ambient temperature (20°C) and at atmospheric pressure. The pH of the test composition is preferably between 8 and 11, in particular between 9 and 10.5.

[0066] The ammonium salt may be chosen from ammonium carbonate, ammonium carbamate, ammonium hydrogencarbonate, ammonium sulfates, ammonium glycerophosphates, ammonium chloride, ammonium nitrate, salts of carboxylic acids, such as ammonium acetate, ammonium fumarate and also ammonium salts of hydroxy acids such as ammonium gluconate, ammonium citrate, tartrate, lactate and malate, or ammonium salts of amino acids such as ammonium aspartate, arginate and glycocholate, and mixtures thereof. The test composition may comprise several ammonium salts, in particular chosen from the preceding list.

[0067] Preferably, said at least one ammonium salt comprises a primary ammonium salt, preferably a carboxylic acid salt, such as ammonium acetate.

[0068] In one embodiment, the test composition contains a single ammonium salt, and preferably the single ammonium salt is a primary salt, and more preferably the single ammonium salt is a carboxylic acid salt such as ammonium acetate. Such a salt produces good results.

[0069] The total content of ammonium salt(s) preferably ranges from 0.08% to 1% by weight, preferably 0.15% to 0.4% by weight, relative to the total weight of the composition.

[0070] The polyol is preferably a diol.

[0071] The polyol may in particular be a vicinal diol or a glycol, and preferably the polyol is a glycol.

[0072] In particular, the polyol may be a glycol comprising between 2 and 7 carbon atoms, limits included, preferably with a linear chain. The glycol preferably comprises between 4 and 6 carbon atoms, preferably with a linear chain. More preferably, the glycol has 5 carbon atoms.

[0073] For the purposes of the invention, a glycol is a diol in which the two hydroxyl groups are borne by different carbon atoms.

[0074] The polyol may in particular be pentylene glycol.

[0075] The total content of polyol(s) may range from 0% to 25% by weight, preferably 6% to 15% by weight, relative to the total weight of the composition.

[0076] The total content by mass of polyol(s), when a polyol is present, is preferably greater than or equal to 10%.

[0077] The hydrogen peroxide is preferably present in a content ranging from 2% to 8% by weight, preferably 3% to 6% by weight, relative to the total weight of the composition.

[0078] The polyol(s) / hydrogen peroxide mass ratio may be between 1 and 5, preferably 2 and 4.

[0079] According to a preferred embodiment of the invention, the test composition comprises between 0.15% and 0.4% by weight of ammonium salt relative to the total weight of the composition, between 3% and 6% by weight of hydrogen peroxide relative to the total weight of the composition, between 6% and 15% by weight of polyol relative to the total weight of the composition, and between 2% and 4% by weight of water relative to the total weight of the composition.

[0080] Testing set for the detection of metal in the hair

[0081] The invention also provides a testing set, also referred to as kit, for the detection of at least one metal, in particular copper, in hair fibres, comprising at least:

[0082] - a test composition as defined above, already ready to use, or compounds and / or solutions enabling, by mixing, such a composition to be produced; and

[0083] - a container intended to receive the test composition and the hair fibres.

[0084] The container is advantageously at least partially transparent or translucent, so as to allow the visualization of bubbles forming at the surface of the hair and an optional backlighting of the composition and of the hair present in the container.

[0085] The compounds and / or solutions enabling, by mixing, the test composition to be produced may be provided in at least two separate receptacles, these for example containing respectively a first aqueous solution buffered to alkaline pH and comprising at least one ammonium salt and a second aqueous solution comprising hydrogen peroxide and preferably at least one polyol.

[0086] Alternatively, the second receptacle comprises solely a polyol. Before mixing with the first solution, aqueous hydrogen peroxide may be added to the second receptacle.

[0087] The container intended to receive the test composition and the hair may advantageously comprise a visual reference indicating the amount of test composition required to test a predefined amount of fibres, for example in the form of a graduation.

[0088] In particular, the visual reference may take the form of at least two graduations indicating the respective amounts to be provided of a first aqueous solution buffered to alkaline pH and comprising an ammonium salt and of a second aqueous solution comprising hydrogen peroxide and preferably a polyol, to be added to the first to produce the test composition with the desired concentrations of each of its constituents.

[0089] The kit may comprise a fibre sampling wand and / or a lighting or backlighting device, preferably taking the form of an illuminated base intended to serve as a support for the container. Preferably, the kit comprises a package housing the container and the test composition (ready to use or in the form of ingredients to be mixed), optionally a sampling wand and / or a lighting or backlighting device.

[0090] The lighting or backlighting device preferably takes the form of an illuminated base intended to serve as a support for the container, this container being at least partially transparent or translucent.

[0091] The lighting or backlighting device may have an electric power of at least 1 watt, better still of at least 1.5 watts.

[0092] The hair fibre sampling wand may comprise a stem that extends along a longitudinal axis X and comprises in a distal portion a slot extending substantially longitudinally so as to form at least one first prong and at least one second prong, the length of the first prong being less than the length of the second prong.

[0093] The first and second prongs, separated by the slot, make it possible in particular to select and hold the hair fibres with a view to sampling them. More specifically, the longer second prong makes it possible to select the hair fibres to be sampled. Once the hair fibres have been selected in the desired amount, the operator may slide these hair fibres into the slot so as to trap them between the first and second prongs of the wand. They may then wind the hair fibres around the first and second prongs before finally cutting off the hair fibres.

[0094] The distal portion of the stem may be bevelled and / or truncated.

[0095] The wand may further comprise a gauge extending transversely to the longitudinal axis X.

[0096] The gauge advantageously makes it possible to more precisely estimate the amount of hair fibres that will be sampled, and thus allows calibrated, fast and precise sampling of fibres. In particular, the sampling of hair fibres in a head of hair by a hairdresser is unpleasant for clients. This is why it is essential to only sample a limited and necessary number of hair fibres. The presence of a gauge is particularly advantageous as it makes it possible to efficiently sample the optimal amount of hair fibres.

[0097] The wand may alternatively or additionally comprise a retaining element intended to retain hair fibres to be sampled on the stem.

[0098] Such a retaining element advantageously makes it possible to transport the hair fibres sampled to a container without loss, while avoiding, if appropriate, any direct contact between the operator and the hair fibres sampled. The gauge may be a hole, an annular groove, or a recess intended to receive hair fibres. In particular, the gauge may form a V lying flush in the stem.

[0099] It may also be advantageous to be able to push the hair fibres sampled down into a container and / or to be able to extract them from the container.

[0100] To this end, the sampling wand may comprise a widened proximal portion, for example having a larger diameter than a median portion of the stem.

[0101] The widened portion may be formed by moulding or cutting, or be an attached endpiece.

[0102] The wand may alternatively or additionally comprise a hook at the proximal end of the wand.

[0103] The wand may have a length greater than 10 cm, and / or less than 20 cm, and preferably the length of the wand is between 13 cm and 17 cm, in particular substantially equal to 15 cm.

[0104] The invention also provides a set for treating a head of hair, comprising:

[0105] - at least one detection kit according to the invention,

[0106] - at least one remediation composition for treating the presence of a metal within the hair in the event of a positive detection, and / or

[0107] - at least one composition for colouring the hair or for shaping the head of hair.

[0108] The treatment set is advantageously packaged in a package.

[0109] The treatment set may comprise several hair treatment compositions, which may or may not be applied depending on the presence or absence of a metal in the hair fibres, these hair treatment compositions being in particular hair colouring compositions.

[0110] The treatment set comprises, for example, at least one colouring composition suitable for colouring the head of hair in the event of a positive test for the presence of metals and at least one colouring composition suitable for colouring the head of hair in the event of a negative test for the presence of metals.

[0111] Process for colouring a head of hair

[0112] Colouring is understood here to mean colouring or bleaching. In other words, colouring of a head of hair should be understood to mean a change in the colour or shade of the head of hair, even a partial one. The invention also provides, according to another of its aspects, a process for colouring a head of hair, comprising the implementation of a process for detecting at least one metal on at least a portion of the hair fibres forming the head of hair, and then, in the event of positive detection of metal, the application of a remediation composition preferably to all of the head of hair, before applying any colouring whatsoever to the head of hair, and / or the application of a colouring suitable for a head of hair contaminated by a metal, and, in the event of negative detection of metal, the application of any colouring whatsoever to the head of hair.

[0113] In particular, a composition suitable for a head of hair comprising a metal may be a composition that provides little lightening, or else a composition comprising specific metal chelating agents such as glycine or a relatively high proportion of sequestering agents such as polyacids (EDTA, GLDA, EDDS).

[0114] The colouring process comprises application of the colouring to the head of hair, which advantageously depends on the results of the implementation of the process for detecting at least one metal.

[0115] In one embodiment, the test and / or oxidation compositions are gelled. In particular, the gelling of the test composition may be adapted so as to facilitate visualization of the evolution of gas.

[0116] Process for detecting undesirable colouring residues and set for implementing the process

[0117] According to another of its aspects, the invention provides a process for revealing the presence or absence of undesirable colouring residues in hair fibres.

[0118] This process for revealing undesirable colouring residues in hair fibres comprises at least one of the following tests: a) bringing hair fibres into contact with an aqueous oxidation composition at alkaline pH comprising at least one oxidizing agent present in a content of between 2% and 15% by weight, relative to the total weight of the oxidation composition, this contacting being carried out at a temperature greater than ambient temperature, b) extracting colouring residues in the hair fibres, by bringing the hair fibres into contact with at least one extraction solvent at a temperature greater than ambient temperature, and observing a possible colouring of the composition following the interaction between the fibres and the composition.

[0119] The phrase “temperature greater than ambient temperature” denotes a temperature at least 10°C above the temperature of the room in which the test is carried out, and this temperature greater than ambient temperature is preferably a temperature strictly greater than 40°C, better still greater than or equal to 50°C.

[0120] Test a) is preferably carried out under hot conditions and makes it possible to rapidly produce a visible result with a relatively small amount of oxidizing composition. The colour of the fibres at the end of the reaction makes it possible to detect any possible undesirable colouring residues. This colour also makes it possible to anticipate a possible problem of nonconformity of the colouring depending on the colouring product initially chosen and to direct the person towards a less-risky alternative colouring.

[0121] Test b) constitutes a preferred alternative solution to test a).

[0122] In contrast to the methods conventionally employed, the process for revealing colouring residues using test b) is not concerned with the colouring that the hair fibres adopt at the end of the test but with the colouring that the composition adopts during the test. It is this colouring that makes it possible to determine the presence or absence of undesirable colouring residues in said fibres.

[0123] The colour adopted by the composition thus gives information allowing the identification of the types of residues present in the hair fibres tested and makes it possible to propose a suitable hair treatment.

[0124] The test composition may thus retain a substantial absence of colouring and then reveal the absence of colouring residues. If the initially colourless, milky or white, or even slightly tinted, composition becomes grey or very chromatic at the end of the test, this means that there is a risk of strongly affecting a subsequent colouring. When the composition, after interaction with the hair fibres, exhibits an orange, red, violet, blue, grey or brown shade, this is indicative of the presence of undesirable colouring residues.

[0125] If the composition is in beige tones at the end of the test, the risk is low or even zero. This is because, if the beige dyes leave behind colouring residues, they are usually removed or masked by the application of a new lightening colouring or bleaching.

[0126] The colouring residues may be residues of indigo, of indigocarmine and / or of chromatic azomethine dyes. The process according to the invention, in particular with test b), is very particularly suitable for revealing indigo or indigocarmine residues, but also applies to the revealing of residues of synthetic chromatic dyes such as azo or azomethine dyes.

[0127] Composition for test a)

[0128] The composition used for test a) is an aqueous oxidation composition at alkaline pH comprising at least one oxidizing agent present in a content of between 2% and 15% by weight relative to the total weight of the oxidation composition.

[0129] The oxidizing agent is preferably hydrogen peroxide. Its concentration may range from 2% to 15% by weight relative to the total weight of the composition.

[0130] The composition may comprise an alkaline compound chosen from aqueous ammonia, amines including monoethanolamine or triethanolamine, hydroxides including sodium hydroxide, potassium hydroxide or calcium hydroxide, alkaline silicates including sodium silicate or sodium metasilicate.

[0131] The pH of the composition (at 20°C) is preferably between 9 and 12.

[0132] Preferably, the oxidation composition used for test a) contains less than 10% by mass of persulfate(s), better still is devoid of ammonium persulfate, in particular devoid of any persulfate.

[0133] The composition may comprise a polyol, preferably a glycol, in particular propylene glycol, pentylene glycol or hexylene glycol, and preferably the polyol is pentylene glycol, the total content by mass of polyol(s) relative to the total weight of the composition preferably ranging from 10% to 70%, better still from 40% to 60%.

[0134] Composition for test b)

[0135] The extraction solvent is preferably chosen from polar, protic or aprotic solvents, in particular water or DMSO (dimethyl sulfoxide), and preferably the composition comprises a mixture of water, an alkaline agent and a polyol.

[0136] The total content by mass of extraction solvent(s) relative to the total weight of the composition is preferably between 50% and 100%, better still between 70% and 90%.

[0137] The alkaline agent is preferably soluble at ambient temperature in the extraction composition. The alkaline agent is preferably chosen from amines, in particular an amine such as aqueous ammonia, triethylamine or triethanolamine, and, preferably, the alkaline agent is monoethanolamine .

[0138] The total content by mass of alkaline agent(s) is preferably between 0.1% and 10% relative to the total weight of the composition, better still between 0.5% and 3%.

[0139] The polyol is preferably a glycol, such as propylene glycol, pentylene glycol or hexylene glycol, and preferably the polyol is pentylene glycol.

[0140] The total content by mass of polyol(s) relative to the total weight of the composition ranges for example from 10% to 70%, better still from 40% to 60%.

[0141] The composition used for test b) may be devoid of any oxidizing agent, in particular of persulfates.

[0142] The pH of the composition (at 20°C) ranges for example from 8 to 12.5, preferably from 9 to 11.

[0143] Implementation steps

[0144] The process may comprise the introduction of the fibres to be tested into the composition and then heating said composition. This makes it possible to avoid handling the composition when it is hot, and thus facilitates the performance of the test.

[0145] The composition and the hair fibres in contact therewith may be heated by any means, in particular by conduction. Preferably, the temperature does not exceed 100°C. The heating step preferably does not exceed 10 minutes.

[0146] The temperature of the composition during the interaction with the fibres is preferably greater than 50°C, and preferably for test b) the temperature is between 70 and 110°C.

[0147] The maintenance of the temperature at a temperature greater than ambient temperature preferably lasts at least 5 minutes for tests a) and b). The process, whether carried out with test a) or b), is particularly fast because the composition is heated, since this accelerates the reactivity of the oxidizing composition or the extraction solvent and the kinetics of the reaction.

[0148] The process comprises, whether for test a) or b), a preliminary step of sampling hair fibres, in particular by means of a fibre sampling wand, for example a sampling wand as defined below. Bringing the hair fibres into contact with the composition may consist in inserting the hair fibres into a container comprising the composition used for test a) or b).

[0149] The composition may be stirred in the presence of the hair fibres to be tested, in particular with the aid of a stirrer or exposure to ultrasound, this stirring making it possible to homogenize the composition and facilitating the interaction of the hair fibres with the composition.

[0150] The determination of the resulting colouring of the composition may be carried out with the aid of a colourimetric reference system.

[0151] The colour of the composition, especially during test b), may be read at the end of the heating step, and may be done for example by using a colour chart.

[0152] The receptacle comprising the composition and hair fibres may be removed from the heating device in order to make it possible to more easily observe the colouring of the composition. If appropriate, the composition is lit or backlit.

[0153] After a predefined interaction time, at least one additive chosen from dithionite, hydrogen chloride, ammonium persulfate or hydrogen peroxide may be added to the composition used for test b).

[0154] The addition of this additive may be carried out when the heating is stopped, the desired interaction having been achieved. The additive is added, for example, at least 5 minutes after the start of bringing the hair fibres into contact with the composition.

[0155] The addition of such an additive may facilitate the revealing of the presence of a particular colouring residue by making it possible to observe the presence or absence of a change in colour, inherent to a reaction between this additive and the extracted dye(s). This change may be known to those skilled in the art or preferably indicated in the instructions for the kit. For example, the addition of dithionite makes it possible to highlight the presence of indigo residues by a shift to yellow of a blue or violet colouring observed during the extraction, temporarily or permanently, the addition of hydrogen chloride makes it possible to highlight the presence of direct dyes or halochromic oxidation dyes, the addition of ammonium persulfate makes it possible to highlight the presence of oxidation dyes and certain direct dyes which are known to be sensitive to superoxidation and are bleached in its presence, and the addition of hydrogen peroxide makes it possible to highlight the presence of certain dyes that are more highly sensitive to oxidation, such as certain oxidation dyes. It is possible first to observe the colouring obtained without the addition of an additive, then to add the additive, and then to observe the colouring again. In both cases, reference may be made to a colourimetric reference system such as a colour chart.

[0156] The colour of the composition may be compared to a colourimetric reference system such as a colour chart, visually, or be analysed by image analysis or by spectrophotometric measurement. This colour chart may form part of the testing set below.

[0157] When a spectrophotometric measurement is performed, the visible ultraviolet absorbance spectrum may be analysed; in particular, the presence of a peak beyond 450 nm, 500 nm or 600 nm may signify the presence of colouring residues.

[0158] Where the analysis of the colour of the composition is carried out by image analysis, the process may comprise the acquisition of at least one image of the container, and then the subjecting of the image to an image processing algorithm, for example a machine learning algorithm, this algorithm being configured to deliver the desired colourimetric information, and possibly interpret it.

[0159] Testing set for implementing the process

[0160] The invention also provides a set, also referred to as a kit, for revealing colouring residues in hair fibres, which can be used for implementing the detection process according to the invention, in variant a) or b) thereof.

[0161] For the implementation of test a), the kit comprises at least one oxidation composition as defined above.

[0162] For the implementation of test b), the kit comprises at least one composition containing an extraction solvent as defined above.

[0163] The amount of composition for test a) or b) is preferably between 1.5 mL and 15 mL, better still between 1.5 mL and 10 mL.

[0164] Thus, the oxidation composition may be packaged in a receptacle the volume of which is less than or equal to 15 mL, preferably less than or equal to 10 mL. It is also possible to use a vial containing an amount of composition to be used for several parallel or successive tests.

[0165] Heating device

[0166] The kit may comprise a heating device. In particular, the heating device is suitable for enabling heating of the composition used for test a) or test b), and in particular for test b), to a temperature of between 70°C and 110°C, preferably between 90°C and 100°C.

[0167] Preferably, the heating is carried out by conduction.

[0168] The heating device may be configured to maintain a predefined heating temperature, in particular of greater than 50°C, for at least 5 minutes.

[0169] The heating device may be configured so that the total heating time does not exceed 10 minutes, and for example may be arranged to automatically stop the heating once a predefined time has elapsed.

[0170] Lighting device

[0171] Preferably, the set comprises a lighting or backlighting device. The lighting or backlighting device preferably takes the form of an illuminated base intended to serve as a support for the container, this container being at least partially transparent or translucent.

[0172] The lighting or backlighting device may have an electric power of at least 1 watt, better still of at least 1.5 watts.

[0173] Container

[0174] The container in which the fibres are brought into contact with the composition used for the test is advantageously at least partially transparent or translucent, in order to allow easy visualization of the colour of the hair fibres and / or of the composition while leaving them in the container, and allow possible backlighting of the composition and of the hair present in the container.

[0175] This container may bear a mark, for example in the form of an engraving or a screen print, making it possible to measure out the amount of composition introduced at the time of the test. wand

[0176] The kit may comprise a wand for sampling the hair fibres to be tested.

[0177] The sampling wand may comprise a stem that extends along a longitudinal axis X and comprises in a distal portion a slot extending substantially longitudinally so as to form at least one first prong and at least one second prong, the length of the first prong being less than the length of the second prong.

[0178] The longer second prong makes it possible to select the hair fibres to be sampled. Once the hair fibres have been selected in the desired amount, the operator may slide these hair fibres into the slot so as to trap them between the first and second prongs of the wand. They may then wind the hair fibres around the first and second prongs before finally cutting them off. The distal portion of the stem may be bevelled and / or truncated.

[0179] The wand may further comprise a gauge extending transversely to the longitudinal axis X. The gauge advantageously makes it possible to more precisely estimate the amount of hair fibres that will be sampled, and thus allows calibrated, fast, and precise sampling of the fibres. In particular, the sampling of hair fibres in a head of hair by a hairdresser is unpleasant for clients. This is why it is essential to only sample a limited and necessary number of hair fibres. The presence of the gauge is particularly advantageous as it makes it possible to efficiently sample the optimal amount of hair fibres.

[0180] The gauge may be a hole, an annular groove, or a recess intended to receive hair fibres. In particular, the gauge may form a V lying flush in the stem.

[0181] The wand may alternatively or additionally comprise a retaining element intended to retain the hair fibres to be sampled on the stem.

[0182] Such a retaining element advantageously makes it possible to transport the hair fibres sampled to the test container without loss, while avoiding, if appropriate, any direct contact between the operator and the hair fibres sampled.

[0183] It may also be advantageous to be able to push the hair fibres sampled down into the container and / or to be able to extract them from the container.

[0184] To this end, the wand may comprise a widened proximal portion, for example having a larger diameter than a median portion of the stem. The widened portion may be formed by moulding or cutting, or be an attached endpiece.

[0185] The wand may alternatively or additionally comprise a hook at the proximal end of the wand. The wand may have a length greater than 10 cm, and / or less than 20 cm, and preferably the length of the wand is between 13 cm and 17 cm, for example being substantially equal to 15 cm. Preferably, the testing kit comprises a package housing the container and the test composition (ready to use or in the form of ingredients to be mixed), optionally the sampling wand and / or a colourimetric reference system such as a colour chart.

[0186] The kit may comprise, if appropriate, the lighting or backlighting device and / or the heating device.

[0187] The kit advantageously comprises a package in which the composition used for test a) or test b), and optionally the sampling wand and / or the colourimetric reference system, are packaged. This package may also contain, if appropriate, the lighting or backlighting device and / or the heating device.

[0188] Hair treatment unit

[0189] The invention also relates to a set for treating a head of hair, comprising:

[0190] - at least one kit for revealing colouring residues according to the invention, as defined above, and

[0191] - at least one hair treatment composition, contained in a separate receptacle, the hair treatment composition preferably being a colouring composition.

[0192] This set may be packaged in a package.

[0193] The set may comprise at least two hair treatment compositions, in two respective separate receptacles, for example a first colouring composition suitable for carrying out colouring in the event of revealing a positive presence of undesirable colouring residues, and a second colouring composition suitable for colouring in the event of revealing a negative presence of undesirable colouring residues.

[0194] The hair treatment composition(s) may in particular be one or more of the following compositions: at least one treatment composition suitable for the presence of undesirable colouring residues in the head of hair, and / or at least one treatment composition suitable for the absence of undesirable colouring residues in the head of hair.

[0195] The treatment compositions may each be a colouring or bleaching composition. In particular, the treatment composition in the event of a positive detection of undesirable colouring residues may be a composition aimed at obtaining a darker colour than the colouring previously performed by the person. Otherwise, the presence of the colouring residues will lead to colours different from those desired, or even an unaesthetic result.

[0196] Brief description of the drawings

[0197] The invention may be understood better from reading the following detailed description of non-limiting exemplary embodiments thereof, and from studying the appended drawing, in which:

[0198] [Fig. 1] Figure 1 schematically represents an example of a testing kit for the detection of at least one metal in hair fibres,

[0199] [Fig. 2] Figure 2 illustrates an example of a treatment set comprising, inter alia, a testing kit for the detection of at least one metal in hair fibres,

[0200] [Fig. 3] Figure 3 schematically shows steps of a treatment process comprising implementing, beforehand, a process for detecting at least one metal in hair fibres, and

[0201] [Fig. 4] Figure 4 is a block diagram illustrating steps of a process for colouring a head of hair,

[0202] [Fig. 5] Figure 5 illustrates an example of a kit according to the invention, for revealing colouring residues in hair fibres,

[0203] [Fig. 6] Figure 6 illustrates an example of a treatment set comprising, inter alia, a kit for revealing colouring residues in hair fibres,

[0204] [Fig. 7] Figure 7 illustrates steps of an example of a detection process according to the invention, and

[0205] [Fig. 8] Figure 8 illustrates steps of an example of a process for treating the hair comprising implementing, prior to the treatment, a process for revealing undesirable colouring residues.

[0206] In the remainder of the description, elements that are identical or have similar functions bear the same reference signs. Their description is not repeated for each of the figures, and only the main differences between the embodiments are mentioned. Detailed description

[0207] Detection of metals in the hair

[0208] Figure 1 illustrates a testing kit 1 for the detection of at least one metal in hair fibres. Figure 2 illustrates a treatment set 3 comprising a testing kit 1 and also a remediation composition 20 and a colouring composition 90.

[0209] Testing kit

[0210] A testing kit 1 comprises at least one test composition 10, which is ready to use, as illustrated in Figure 1, or in the form of compounds or solutions contained in receptacles

[0211] 14 and 15, to be mixed extemporaneously, and a container 11, as illustrated in Figure 2.

[0212] The test composition is, at the time of use, an aqueous solution at alkaline pH comprising at least one ammonium salt, hydrogen peroxide and preferably at least one polyol, in particular a glycol, as detailed above.

[0213] The container 11 may comprise, as can be seen in Figure 2, graduations 12 ,13 indicating the amounts of the compounds or solutions originating from the receptacles 14,

[0214] 15 to be mixed in order to obtain the test composition 10.

[0215] For example, the first graduation 12 corresponds to the filling with an aqueous solution at alkaline pH comprising at least one ammonium salt originating from the receptacle 14 and the second graduation 13 indicates the remainder to be provided of the second solution contained in the receptacle 15.

[0216] The compounds to be mixed in order to obtain the test composition are not necessarily in liquid form and at least some of them may be in solid form, for example in the form of powder, granules or capsules.

[0217] The entirety of the testing kit is advantageously packaged in a package 50, for example a blister pack, a cardboard box, or a pouch.

[0218] The testing kit 1 may also comprise, as illustrated in Figure 1, a hair fibre sampling wand 30 and / or a lighting device 40 configured to enable the composition to be backlit at the time of the test.

[0219] The container 11 may be at least partially transparent or translucent.

[0220] The lighting device 40 is preferably in the form of an illuminated base allowing the backlighting of the container 11 when the latter is positioned thereon. In one particular embodiment, the illuminated base 40 is configured so as to also enable the test composition 10 to be stirred. For example, the base 40 may emit ultrasound and / or operate with a magnetic bar (not shown) so as to form a magnetic stirrer.

[0221] The testing kit 1 may also be included within a set for treating a head of hair 3, with a remediation composition 20 and / or at least one colouring composition 90.

[0222] The treatment set 3 may comprise several colouring compositions, each colouring composition being suitable for example for being applied to a head of hair for which a certain content of at least one metal has been detected, so as to adapt the choice of the colouring to the result of the test carried out beforehand.

[0223] Detection process

[0224] Various steps of a process for treating a head of hair 110 comprising the implementation of a process 100 for detecting the presence of at least one metal in hair fibres are shown schematically in Figure 3.

[0225] The detection process comprises at least one step 101 of providing a test composition, and a step 103 of bringing hair fibres into interaction with the test composition.

[0226] In step 101, the test composition may be prepared by mixing compounds and / or solutions in a container.

[0227] Alternatively, the test composition is provided already mixed, preferably directly in the container intended to receive the hair fibres.

[0228] The container can be positioned with respect to a lighting device 40 as mentioned above, so as to enable the test composition to be backlit.

[0229] The process 100 for detecting the presence of at least one metal in hair fibres preferably comprises a step of sampling hair fibres 102, for example by means of a sampling wand 30 as mentioned above.

[0230] The sampled hair fibres can then be introduced, during step 103 of bringing the fibres into interaction with a test composition, into the container housing the test composition, so as to enable the generation of a possible evolution of dioxygen gas at the surface of the fibres, the presence of such an evolution of gas reflecting the presence of at least one metal in the hair fibres.

[0231] During an optional step 104, the amount of dioxygen evolved during step 103 is measured, making it possible to determine a metal content present in the hair fibres. Depending on the result of the test, that is to say depending on the presence of an evolution of gas or beyond an estimated metal content in the hair fibres, a remediation composition 20 may be applied to the hair fibres, during a step 105.

[0232] In one particular embodiment of the treatment process 110, after the step 105 of applying the remediation composition, the steps of the process for detecting at least one metal in the hair fibres are repeated.

[0233] Process for colouring a head of hair

[0234] Figure 4 is a block diagram representing steps of a process 300 for colouring a head of hair according to the invention.

[0235] The application of a colouring product to a head of hair produces a result that depends on the initial condition of the hair. Numerous parameters, such as the starting colour, hair fragility, texture, swimming pool attendance, use of particular treatments, prior application of colouring, can influence the final result.

[0236] The colouring process preferably comprises a preliminary step 301 of evaluating the condition of the hair, depending for example on one or more of the following parameters: starting colour, hair fragility, texture, swimming pool attendance, use of particular treatments, prior application of colouring, and composition of the desired colouring.

[0237] The colouring process 300 comprises the implementation of the detection process 100.

[0238] Depending on the results, the evaluation of the condition of the hair may be refined during a step 302.

[0239] If the amount of metal, in particular copper, in the hair is low or zero, and no other colouring residue has been revealed, then the desired colouring can be applied in step 305.

[0240] If the amount of metals, in particular copper, in the hair is high or medium, for example greater than or equal to 50 ppm, a remediation composition can be applied 303.

[0241] If the presence of colouring residues liable to affect the desired colouring is revealed, an alternative colouring can be applied in step 304.

[0242] After applying a remediation composition in step 303, an alternative colouring can be applied in step 304 or the desired colouring is applied in step 305. Optionally, after applying a remediation composition in step 303, the metal detection process 100 is implemented again in order to verify that the metal content has indeed decreased.

[0243] Tests

[0244] Tests were carried out in order to observe the effectiveness of a test composition according to the invention for the detection of at least one metal, in particular copper, in hair fibres.

[0245] 9 samples Ei of 60 mg of hair fibres are considered, i ranging from 1 to 9, each sample having been divided into two equal parts Ei,i and Ei,2.

[0246] For each sample Ei,i, the fibres of the sample are ground by a ball mill, so as to obtain a pellet of 30 mg of ground hair fibres, an X-ray fluorescence measurement of the pellet then being carried out so as to determine a copper content in each sample.

[0247] Alternatively, an inductively coupled plasma spectrometry (ICP-OES) method using each sample Ei,i after mineralization of the latter with nitric acid is implemented in order to determine a copper content in each sample.

[0248] Then, for each sample Ei,2, the intensity of bubbling while said sample Ei,2 is brought into interaction with a given composition is observed.

[0249] Samples EI,2, £2,2 and E3.2 are brought into interaction with a composition Ci of 10 mL, consisting of 4 mL of a solution comprising ammonium acetate in a concentration of 0.77 g / 100 g of solution and 6 mL of 40 vol. aqueous hydrogen peroxide. Composition Ci has a pH of 9.8.

[0250] Samples £4.2, E5.2 and Ee.2 are brought into interaction with a composition C2 of 10 mL, consisting of 4 mL of a solution comprising ammonium acetate in a concentration of 0.77 g / 100 g of solution and 6 mL of 33 vol. aqueous hydrogen peroxide comprising 20% by volume of pentylene glycol. Composition C2 has a pH of 9.6.

[0251] Samples £7.2, Es.2 and E9.2 are brought into interaction with a composition C3 of 42 mL, consisting of 2 mL of an aqueous solution comprising 20% aqueous ammonia and 40 mL of 20 vol. aqueous hydrogen peroxide. Composition C3 has a pH of 10.

[0252] Composition C3 (without ammonium salt) corresponds to a composition described in the prior art. The bubbling intensities observed were determined against a bubbling intensity scale ranging from 0 to 8, with 0 indicating an absence of bubbles. The reference scale is presented in Table 2.

[0253] The results of the tests are listed in Table 1 below: [Table 1]

[0254] A metal content of 0 ppm corresponds to an absence of metal or the presence of metal in a negligible amount. In general, a metal content of strictly less than 30 ppm is considered to be low or negligible, a metal content of strictly greater than 150 ppm is considered to be high, and a metal content of between 30 ppm and 150 ppm is considered to be medium.

[0255] Sample EI,2, when it is brought into interaction with the composition Ci, produces a reaction leading to the formation of bubbles even though no metal is present (metal content equal to 0 ppm). Furthermore, a metal content of 50 ppm corresponds to a medium amount of metal in the hair fibres, while a content of 200 ppm corresponds to a high amount of metals in the hair fibres. However, the bubbling intensity is relatively close irrespective of whether the metal content is low or zero (0 ppm), medium (50 ppm) or high (200 ppm).

[0256] Similarly, when samples £7.2, Ex.2 and E9.2 are brought into interaction with the composition C3, they produce a similar bubbling intensity, even though the metal contents of samples E?.i, Es,i and Eg,i are low, medium and high, respectively.

[0257] Samples £4.2, E5.2 and Ee,2 were brought into interaction with a test composition C2 according to the invention. These examples show that the observation of a bubbling intensity, i.e. the presence of a more or less significant evolution of dioxygen, makes it possible to discriminate a low metal content in hair fibres (15 ppm), a medium metal content (50 ppm) and a high metal content (200 ppm). Specifically, for a low metal content in the hair fibres (sample E4), no bubbles are observed. The metal content in the hair fibres is negligible. For a medium metal content in the hair fibres (sample E5), a medium intensity of bubbles is observed. Lastly, for a high metal content in the hair fibres (sample Ee), a high bubbling intensity is observed, 8 on a scale from 0, absence of bubbles, to 8. This demonstrates the utility of the presence of polyol in the test composition.

[0258] [Table 2]

[0259] The invention makes it possible to carry out a rapid analysis of the condition of the hair before applying a hair treatment, in particular a colouring product. Thus, it is possible to determine which hair products it is possible to apply without a risk of obtaining an undesirable result.

[0260] The detection process according to the invention can be performed regularly so as to establish a temporal monitoring of the amount of metal present in a person’s head of hair, and thus to indicate to them suitable products for preventing or limiting contamination of their hair.

[0261] Process for detecting undesirable colouring residues and set for implementing the process

[0262] Figure 5 schematically represents an example of a kit 2 according to the invention, for revealing colouring residues in the hair fibres.

[0263] Figure 6 represents a treatment set 3 comprising this kit 2 and one or more colouring compositions 90a, 90b.

[0264] The kit 2 is preferably packaged in a package 50, for example a cardboard box, just like the treatment set 3.

[0265] The kit 2 comprises at least one composition 70 making it possible to carry out test a) or b) of the detection process according to the invention, as defined above.

[0266] The composition 70 may thus comprise an oxidizing agent in the case of test a), for example aqueous hydrogen peroxide, and an extraction solvent in the case of test b), as detailed above. The composition 70 is packaged in a receptacle 71, which can serve as a container for the test, by receiving the hair fibres.

[0267] The kit 2 may also comprise, as illustrated, a wand 30 for sampling the hair fibres and a heating device 80, both represented schematically.

[0268] The heating device 80 is, for example, suitable for directly receiving the receptacle 71, into which hair fibres to be tested will have been introduced. Preferably, the heating device 80 is configured to heat the contents of the receptacle 71 by conduction. The receptacle 71 is preferably at least partially transparent or translucent, so as to make it possible to easily see the colour of the composition and of the hair fibres tested.

[0269] The detection process according to the invention may comprise, as illustrated in Figure 7, a step 201 of sampling the hair fibres to be tested, preferably by means of the sampling wand 30, the selection and sampling of the fibres being carried out, for example, in the manner detailed above.

[0270] The hair fibres are then inserted into the receptacle 71 comprising the composition 70, so as to enable the composition 70 to be brought into contact with the hair fibres during a step 202.

[0271] Alternatively, the oxidation composition 70 is added to the receptacle 71 after the hair fibres have been inserted therein. A visual reference 72 on the receptacle 71 may indicate the volume of composition to be inserted into the receptacle.

[0272] The composition 70 is preferably packaged in an amount suitable for a single use. Thus, the composition 70 can be packaged in a small amount, preferably in a volume of less than 15 mL.

[0273] The receptacle 71 comprising the hair fibres in contact with the composition 70 can be deposited in the heating device 80, in order to perform a heating step 203 at a predefined temperature and for a predefined period of time.

[0274] In step 204, the composition is removed from the heating device 80 in order to be placed under conditions that enable the result of the test to be visually observed.

[0275] This visual observation may consist in determining the colouring of the composition 70 and / or of the hair fibres.

[0276] A colourimetric reference system such as a colour chart N may be used to help visually determine the observed colour, this colour chart comprising for example several areas of solid colour of different shades and / or saturations CO, Cl, C2, C3, C4. These areas of solid colour may have been printed, if appropriate, on the testing kit package or on a separate instructions sheet.

[0277] This comparison can also be done automatically, for example by image processing. An image of the colour of the composition 70 at the end of the test can be acquired and processed by computer. For example, the image can be acquired with a mobile phone, and a mobile application is used to automatically determine whether the colour obtained reflects the presence of colouring residues or not. In one particular embodiment, the composition 70 is subjected after the test to spectrophotometric analysis.

[0278] If appropriate, an additive making it possible to better characterize the nature of the colouring residue(s) detected is introduced into the composition, as mentioned above. This additive may be packaged in a specific container, present within the package 50.

[0279] Figure 8 is a block diagram representing steps of an example of a process 300 for colouring a head of hair according to the invention.

[0280] This colouring process 300 may comprise a preliminary step 301 of collecting information on the hair to be treated, such as for example the starting colour, hair fragility, texture, possible swimming pool attendance, use of particular treatments, prior application of colourings, and nature of the desired colouring. This information may be taken into account when subsequently recommending the colouring treatment to be carried out, once the test has been carried out.

[0281] The colouring process 300 then comprises the implementation of one of tests a) and b) of the detection process according to the invention.

[0282] Depending on the result of the test, the evaluation of the condition of the hair may optionally be refined during a step 302, by taking into account the information received in step 301.

[0283] Depending on the result of the test and the condition of the hair determined in step 302, it may be recommended not to apply any colouring in step 303, or to apply an alternative colouring suitable for the condition of the hair in step 304, or to apply the desired colouring in step 305.

[0284] Tests

[0285] Tests were carried out in order to observe the effectiveness of the process for revealing colouring residues according to the invention.

[0286] Several locks Mk, k ranging from 1 to 6, were coloured according to the table below.

[0287] The locks Mk with k ranging from 1 to 2 were rinsed and dried with a hairdryer and then stored for three days. The locks Mk with k ranging from 3 to 6 were rinsed, shampooed, rinsed and then dried. All of the locks were then washed ten times in order to remove the usual dye residues.

[0288] A bleaching was then applied to a first portion of each of said locks Mk so as to determine whether or not the possible residues present in each lock Mk impair the bleaching or not. This bleaching was carried out using a L’Oreal Professionnel Blond Studio 8 bleaching powder based on potassium and ammonium persulfates, sodium metasilicate and magnesium carbonate, mixed before use with a formula based on aqueous hydrogen peroxide at 30 volumes (9%) in a mass ratio of 1 to 1.5. The bleaching mixture was applied at a rate of 10 g per 1 g of hair, on a plate preheated to 33°C, for 50 minutes. It was then rinsed under running water and a shampoo wash was carried out. The colour of the locks was observed after drying.

[0289] The residues were considered to impair the bleaching if the colour obtained tends towards grey or if tints differing from natural tints, for example blue, green, red or violet tints, are observed.

[0290] Two days after application of the colouring, a series of 10 non-treating shampoo washes is carried out, the lock being dried between each shampoo wash. This series of shampoo washes is useful for removing excess dyes and corresponds to the normal loss of this excess during the first days or weeks after colouring. These shampoo washes do not make it possible to remove all of the residues, especially those that are the most problematic.

[0291] The process for revealing colouring residues is performed on a second portion of each of the locks Mk.

[0292] Each second portion of the locks Mk was brought into interaction, in a vial, with 10 mL of a composition Sk for the implementation of test b), k ranging from 1 to 6, consisting of 50 g of pentylene glycol, 49 g of water and 1 g of monoethanolamine. The vial was then heated for 7 minutes and 30 seconds at 95 °C and then allowed to cool in the open air. After cooling, the colours of the compositions Sk, respectively brought into interaction with the second portions of the locks Mk, were analysed. Each composition Sk was observed under D65 natural light, and an ultraviolet- visible absorbance spectrum was produced. The results observed are summarized in the following table.

[0293] The colours observed for the locks Mi to Ms tested are problematic, which is confirmed by the bleaching tests carried out.

[0294] The colour observed at the end of the test of lock Me is not problematic. If a substantially colourless composition is observed, it could also be concluded that there is no problem.

[0295] Of course, the invention is not limited to the examples illustrated.

[0296] In particular, the formulation of the test compositions can be modified without departing from the scope of the present invention.

Claims

Claims1. Process for detecting the presence of at least one metal, in particular copper, in hair fibres, comprising bringing the hair fibres into contact with a test composition (10) comprising, in aqueous medium at alkaline pH, at least one ammonium salt, and hydrogen peroxide, so as to enable the generation of a possible evolution of dioxygen gas at the surface of the hair fibres, the presence of such an evolution of gas revealing the presence of said metal in the hair fibres.

2. Process according to the preceding claim, the composition having a pH of greater than or equal to 9.4, better still 9.6.

3. Process according to either of Claims 1 and 2, comprising a preliminary step of preparing the test composition, in particular extemporaneously.

4. Process according to one of the preceding claims, the composition comprising at least one polyol.

5. Process according to any one of the preceding claims, wherein the ammonium salt is chosen from ammonium carbonate, ammonium carbamate, ammonium hydrogencarbonate, ammonium sulfates, ammonium glycerophosphates, ammonium chloride, ammonium nitrate, salts of carboxylic acids, in particular ammonium acetate, ammonium fumarate and also ammonium salts of hydroxy acids such as ammonium gluconate, ammonium citrate, tartrate, lactate and malate, or ammonium salts of amino acids such as ammonium aspartate, arginate and glycocholate, and mixtures thereof.

6. Process according to any one of the preceding claims, wherein the ammonium salt is a primary ammonium salt, preferably a carboxylic acid salt, preferably ammonium acetate.

7. Process according to any one of the preceding claims, the composition comprising a polyol, the polyol being a diol, preferably a vicinal diol or a glycol.

8. Process according to any one of the preceding claims, the composition comprising a polyol, the polyol being a glycol having between 2 and 7 carbon atoms, preferably with a linear chain, and more preferably a glycol having from 4 to 6 carbon atoms.

9. Process according to any one of Claims 4 to 8, wherein the polyol / hydrogen peroxide mass ratio of the test composition is between 1 and 5, preferably 2 and 4.

10. Process according to any one of the preceding Claims 4 to 8, wherein the test composition comprises between 0.15% and 0.4% by weight of ammonium salt relative to the total weight of the composition, between 3% and 6% by weight of hydrogen peroxide relative to the total weight of the composition, between 6% and 15% by weight of polyol relative to the total weight of the composition, and between 2% and 4% by weight of water relative to the total weight of the composition.

11. Process according to any one of the preceding claims, comprising the quantification of the dioxygen produced.

12. Process according to the preceding claim, comprising a comparison of the amount of dioxygen produced or of the corresponding amount of metal with a reference value, in particular the comparison of the amount of metal with a threshold value beyond which the amount of metal present in the hair fibres is liable to impair a subsequent colouring treatment of said hair fibres, this threshold value preferably being chosen between 40 ppm and 200 ppm, in particular between 50 and 100 ppm.

13. Process according to any one of the preceding claims, comprising the following successive steps:1) taking a sample of hair fibres, in particular by means of a sampling wand (30);2) providing a test composition or providing compounds and / or solutions that, by mixing, enable such a test composition to be produced;3) bringing the test composition into contact with the hair fibres to be tested, for at least 2 minutes and preferably at most 7 minutes, more preferably at most 5 minutes, so as to place said hair fibres under conditions for interacting with the test composition, the presence of a metal within the hair fibres being reflected by the formation of bubbles at the hair fibres and possibly by the rising of the bubbles to the surface of the composition.

14. Process according to any one of the preceding claims, wherein the composition is prepared in contact with the hair fibres.

15. Process according to the preceding claim, comprising contacting of the hair fibres with a first, alkaline solution and then addition of a second, hydrogen peroxide solution.

16. Process according to any one of the preceding claims, wherein, in the event of positive detection of the presence of a metal, a remediation composition is applied to the hair fibres so as to remove and / or isolate the detected metal.

17. Process according to any one of the preceding claims, comprising backlighting of the test composition during the possible evolution of gas.

18. Testing kit (1) for the detection of at least one metal in hair fibres, comprising at least: a test composition (10) comprising, in aqueous medium at alkaline pH, at least one ammonium salt, and hydrogen peroxide, the composition preferably additionally comprising at least one polyol, the composition already being ready to use, or the kit comprising compounds and / or solutions enabling, by mixing, such a composition to be produced; and a container (11) intended to receive the test composition and the hair fibres.

19. Kit according to the preceding claim, wherein the compounds and / or solutions enabling, by mixing, the test composition to be produced are provided in at least two separate receptacles, these preferably containing respectively a first aqueous solution buffered to alkaline pH and comprising at least one ammonium salt and a second aqueous solution comprising hydrogen peroxide and preferably at least one polyol.

20. Kit according to either of Claims 18 and 19, comprising a package (50) in which the container and the test composition or the compounds for producing the test composition, and optionally a sampling wand (30), and optionally a lighting device (40), are packaged.

21. Set for treating a head of hair, comprising: at least one detection kit according to any one of Claims 18 to 20, at least one remediation composition for treating the presence of a metal within the hair in the event of a positive detection, and / or at least one composition for colouring the hair or for shaping the head of hair.

22. Process for revealing undesirable colouring residues in hair fibres, this process comprising a preliminary step of sampling the hair fibres and at least one of the following tests: a) bringing, in a container, hair fibres into contact with an aqueous oxidation composition (70) at alkaline pH comprising at least one oxidizing agent present in a contentof between 2% and 15% by weight, relative to the total weight of the oxidation composition, this contacting being carried out at a temperature greater than ambient temperature, or b) extracting colouring residues in the hair fibres, by bringing, in a container, the hair fibres into contact with at least one extraction solvent at a temperature greater than ambient temperature, and observing a possible colouring of the composition following the interaction between the fibres and the composition.

23. Process according to the preceding claim, comprising test a).

24. Process according to Claim 23, the composition comprising an oxidizing agent in a proportion by mass of between 2% and 15%, relative to the total weight of the composition.

25. Process according to either of Claims 23 and 24, the oxidizing agent being hydrogen peroxide.

26. Process according to Claim 22, comprising test b).

27. Process according to Claim 26, the extraction solvent being chosen from polar, protic or aprotic solvents, in particular water or DMSO (dimethyl sulfoxide).

28. Process according to Claim 26 or 27, the total content by mass of extraction solvent(s) being between 50% and 100%, relative to the total weight of the composition, and better still between 70% and 90%.

29. Process according to one of Claims 26 to 28, the composition comprising a polyol, preferably a glycol, in particular propylene glycol, pentylene glycol or hexylene glycol, and preferably the polyol is pentylene glycol, the total content by mass of polyol(s) relative to the total weight of the composition preferably ranging from 10% to 70%, better still from 40% to 60%.

30. Process according to any one of Claims 26 to 29, the composition comprising an alkaline agent, preferably chosen from amines, in particular an amine such as aqueous ammonia, triethylamine or triethanolamine, and, preferably, the alkaline agent is monoethanolamine .

31. Process according to any one of the preceding claims, comprising the introduction of the fibres into the composition and then the heating of the composition.

32. Process according to one of Claims 22 to 31, wherein the temperature of the composition during the interaction with the fibres is greater than 50°C, and this temperature is preferably maintained for at least 5 minutes.

33. Process according to any one of Claims 22 to 32, comprising the determination of the resulting colouring of the composition with a colourimetric reference system (N).

34. Process according to any one of Claims 22 to 33, the colouring residues being residues of indigo, of indigocarmine and / or of chromatic azomethine dyes.

35. Process according to any one of Claims 22 to 34, the composition used for test a) containing less than 10% by mass of persulfate(s), better still being devoid of ammonium persulfate, in particular being devoid of any persulfate, and the composition for test b) being devoid of any oxidizing agent, in particular of persulfates.

36. Process according to any one of claims 26 to 30, wherein in the case of test b), after a predefined interaction time, at least one additive is added to the composition, this additive preferably being chosen from dithionite, hydrogen chloride, ammonium persulfate, or hydrogen peroxide.

37. Process according to any one of Claims 22 to 36, the preliminary sampling step being carried out by means of a fibre sampling wand (30).

38. Process for colouring a head of hair, comprising the implementation of a process for revealing colouring residues according to any one of Claims 22 to 37, and then, depending on the result of the test, the application of a colouring suitable for the presence or absence of residues.

39. Kit for revealing colouring residues in hair fibres, for implementing the process according to any one of Claims 22 to 37, comprising:- at least one oxidation composition (70) at alkaline pH comprising at least one oxidizing agent present in a content of between 2% and 15% by weight relative to the total weight of the oxidation composition, packaged in a receptacle with a volume of less than or equal to 15 mL, preferably less than or equal to 10 mL, or- at least one composition comprising an extraction solvent, and preferably also comprising an alkaline agent and a polyol.

40. Kit according to Claim 39, further comprising a fibre sampling wand (30).

41. Kit according to either of Claims 39 and 40, further comprising a heating device (80).

42. Set for treating a head of hair, comprising:- at least one kit (2) for revealing colouring residues according to any one of Claims 39 to 41, and- at least one hair colouring composition, contained in a separate receptacle.

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