Method for detecting undesirable color residues and assembly for its implementation

Abstract

Method for detecting undesirable color residues and assembly for its implementation. Method for detecting undesirable color residues in hair fibers, this method comprising at least one of the following tests: Contacting the hair fibers with an aqueous oxidizing composition at alkaline pH comprising at least one oxidizing agent present at a concentration of between 2 and 15% by weight relative to the total weight of the oxidizing composition, this contact being carried out at a temperature above ambient temperature; or extracting color residues from the hair fibers by contacting the hair fibers with at least one extraction solvent at a temperature above ambient temperature, and observing any possible coloring of the composition following the interaction between the fibers and the composition. Figure for the abstract: Fig. 3

Description

Title of the invention: Method for detecting undesirable color residues and assembly for its implementation technical field

[0001] The present invention relates to the field of hair treatments.

[0002] The invention relates in particular to a method for demonstrating the presence within the hair of undesirable compounds that may impact a hair coloring or bleaching treatment. Previous technique

[0003] Some colorings leave coloring residues in the hair which can negatively impact the result of a subsequent coloring or bleaching treatment.

[0004] These undesirable color residues may come from natural coloring. Natural coloring is coloring formulated with plants and natural active ingredients, such as henna, eclipta prostrata, indigo, safflower, woad or fruit powders, for example Indian gooseberry.

[0005] Dyes whose residues will be problematic may also come from the previous application of direct coloring products, for example azo dyes, or even from certain oxidation coloring products which lead to the formation of particularly chromatic azomethine dyes.

[0006] It is therefore standard practice in hairdressing schools to perform a preliminary test on a strand of hair to check the result of the subsequent application of a hair treatment product. To this end, before applying the product intended for use on the entire head of hair, a small amount is used only on an isolated strand to verify that the result obtained corresponds to what is expected.

[0007] This practice takes a considerable amount of time because it requires leaving the product to act on the wick used for the test, typically for about twenty minutes.

[0008] Moreover, the product applied to the strand for the test generally comes from the same packaging as that used to treat the whole head of hair, so that if the result does not correspond to the expected result, the rest of the product contained in the opened packaging cannot be applied and will be lost, since it cannot be used quickly on another person.

[0009] An alternative is to apply a bleaching product under normal conditions of use, which allows the hairdresser to identify certain residues of Staining by visualizing these dyes against a lightened background. This alternative usually requires an even longer testing time, on the order of 50 minutes. Description of the invention

[0010] Thus, there is a need to facilitate the establishment of a diagnosis of the presence of undesirable compounds in hair fibers and to identify them.

[0011] There is also an interest in accelerating the detection of potential adverse effects before applying hair coloring or bleaching. Summary of the invention

[0012] The invention aims to meet all or part of these needs, and it achieves this by proposing a method for highlighting the presence or absence of undesirable color residues in hair fibers.

[0013] This method for detecting undesirable color residues in hair fibers includes at least one of the following tests: a) Contacting the hair fibers 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 contact being carried out at a temperature above ambient temperature, b) the extraction of colour residues in hair fibres, by bringing the hair fibres into contact with at least one extraction solvent, at a temperature above ambient temperature, and the observation of any colouring of the composition following the interaction between the fibres and the composition.

[0014] By "temperature above ambient temperature" is meant a temperature that is at least 10°C higher than the temperature of the room where the test is carried out, and this temperature above ambient temperature is preferably a temperature strictly above 40°C, better above or equal to 50°C.

[0015] Test a) is preferably performed under heat and allows for the rapid production of a visible result with a relatively small amount of oxidizing agent. The color of the fibers after the reaction allows for the detection of any undesirable color residues. This color also makes it possible to anticipate any potential color inconsistency with the initially chosen coloring product and to guide the individual toward a less risky alternative coloring method.

[0016] Test b) constitutes a preferred alternative solution to test a).

[0017] Unlike conventionally used methods, the process for detecting color residues using test b) focuses not on the color that the hair fibers acquire at the end of the test, but on the color that takes the composition during the test. It is this coloration that allows the presence or absence of undesirable coloration residues in said fibers to be determined.

[0018] The color taken by the composition thus provides information enabling the identification of the types of residues present in the tested hair fibers and allows for the proposal of an appropriate hair treatment.

[0019] The test composition can thus maintain a significant absence of color and thereby reveal the absence of color residues. If the composition, initially colorless, milky, or white, or even slightly tinted, becomes gray or highly chromatic at the end of the test, this indicates a risk of significantly impacting subsequent coloring. When the composition, after interaction with the hair fibers, displays an orange, red, violet, blue, gray, or brown tint, this is indicative of the presence of undesirable color residues.

[0020] If the composition is in beige tones at the end of the test, the risk is low or even non-existent. Indeed, if beige dyes leave coloring residues, they are usually removed or masked by the application of a new lightening dye or bleaching treatment.

[0021] The colouring residues may be residues of indigo, indigocarmine and / or chromatic azomethine-type dyes.

[0022] The method according to the invention, in particular with test b), is particularly suitable for the detection of residues of indigo or indigocarmine, but is also applicable to the detection of residues of synthetic chromatic dyes such as azo or azomethine dyes. Composition for test a)

[0023] 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.

[0024] The oxidizing agent is preferably hydrogen peroxide. Its concentration can range from 2% to 15% by weight relative to the total weight of the composition.

[0025] The composition may include an alkali compound selected from ammonia, amines including monoethanolamine or triethanolamine, hydroxides including sodium hydroxide, potassium hydroxide or calcium hydroxide, alkali silicates including sodium silicate or sodium metasilicate.

[0026] The pH of the composition (at 20°C) is preferably between 9 and 12.

[0027] Preferably, the oxidation composition used for test a) contains less than 10% by mass of persulfate(s), better is free of ammonium persulfate, in particular free of any persulfate. Composition for test b)

[0028] 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 mass content of polyol(s) relative to the total weight of the composition preferably ranging from 10% to 70%, better from 40% to 60%.

[0029] The composition may include an alkali agent, preferably selected from the amines, in particular an amine such as ammonia, triethylamine or triethanolamine, and preferably the alkali agent is monoethanolamine.

[0030] 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.

[0031] The total mass content of extraction solvent(s) relative to the total weight of the composition is preferably between 50% and 100%, better between 70% and 90%.

[0032] The alkaline agent is preferably soluble at room temperature in the extraction composition.

[0033] The alkali agent is preferably chosen from among the amines, in particular an amine such as ammonia, triethylamine or triethanolamine, and preferably the alkali agent is monoethanolamine

[0034] The total mass content of alkali agent(s) is preferably between 0.1% and 10% relative to the total weight of the composition, better between 0.5% and 3%.

[0035] The polyol is preferably a glycol, such as propylene glycol, pentylene glycol or hexylene glycol, and preferably the polyol is pentylene glycol.

[0036] The total mass content of polyol(s) relative to the total weight of the composition ranges for example from 10% to 70%, or better yet from 40% to 60%.

[0037] The composition used for test b) may be free of any oxidizing agent, and in particular of persulfates.

[0038] The pH of the composition (at 20°C) ranges for example from 8 to 12.5, preferably from 9 to 11. Implementation steps

[0039] The process may include introducing the fibers to be tested into the composition, then heating the composition. This avoids handling the composition while it is hot, and thus facilitates carrying out the test.

[0040] The composition and the hair fibers in contact with it can 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.

[0041] The temperature of the composition during interaction with the fibers is preferably above 50°C, and preferably for test b) the temperature is between 70 and 110°C.

[0042] Maintaining the temperature above ambient temperature preferably lasts at least 5 minutes for tests a) and b). The process, whether implemented with tests a) or b), is particularly rapid because the composition is heated, as this accelerates the reactivity of the oxidizing composition or extraction solvent, and the kinetics of the reaction.

[0043] The process includes, for tests a) and b), a preliminary step of collecting hair fibers, in particular by means of a fiber sampling rod, for example a sampling rod as defined later.

[0044] Contacting the hair fibers with the composition can consist of inserting the hair fibers into a container containing the composition used for test a) or b).

[0045] The composition can be agitated in the presence of the hair fibers to be tested, in particular using a stirrer or exposure to ultrasound, this agitation allowing the composition to be homogenized and facilitating the interaction of the hair fibers with the composition.

[0046] The determination of the resulting colour of the composition can be carried out using a colourimetric reference.

[0047] Reading the colour of the composition, in particular during test b), can occur at the end of the heating step, and can be done for example by using a colour chart.

[0048] The container holding the composition and the hair fibers can be removed from the heating device to allow for easier observation of the composition's color. If necessary, the composition is illuminated or backlit.

[0049] 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).

[0050] This additive can be added after the heating has stopped, once the desired interaction has been achieved. For example, the additive is added at least 5 minutes after the hair fibers have been brought into contact with the composition.

[0051] The addition of such an additive can facilitate the detection of a particular color residue by allowing observation of the presence or absence of a color change inherent in 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 kit instructions. For example, the addition of dithionite makes it possible to highlight the presence of indigo residues by turning a blue or violet color observed during extraction yellow, either 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 that are notoriously sensitive to over-oxidation and are decolorized in its presence, and the addition of hydrogen peroxide helps to accentuate the highlighting of the presence of certain dyes more strongly sensitive to oxidation such as certain oxidation dyes.

[0052] It is possible to first observe the coloration obtained without the addition of any additive, then to add the additive, and then to observe the coloration again. In both cases, reference can be made to a colorimetric reference such as a color chart.

[0053] The color of the composition can be compared to a colorimetric reference such as a color chart, visually, or analyzed by image analysis or spectrophotometric measurement. This color chart may be part of the test set below.

[0054] When a spectrophotometric measurement is carried out, the ultraviolet visible absorbance spectrum can be analyzed, in particular the presence of a peak beyond 450 nm, 500 nm or 600 nm may signify the presence of colour residues.

[0055] When the color analysis of the composition is carried out by image analysis, the process may include acquiring at least one image of the container, then submitting the image to an image processing algorithm, for example a machine learning algorithm, this algorithm being configured to deliver the colorimetric information sought, and possibly interpret it. Test set for implementing the process

[0056] The invention also relates to an assembly, also called a kit, for highlighting color residues in hair fibers, usable for implementing the detection method according to the invention, in its variants a) or b).

[0057] For the implementation of test a), the kit includes at least one oxidation composition as defined above.

[0058] For the implementation of test b), the kit includes at least one extraction solvent composition as defined above.

[0059] The quantity of composition for test a) or b) is preferably between 1.5 mL and 15 mL, better between 1.5 mL and 10 mL.

[0060] Thus, the oxidation composition can be packaged in a container with a volume less than or equal to 15 mL, preferably less than or equal to 10 mL. It is also possible to use a bottle containing a quantity of composition to be used for several parallel or successive tests. Heating device

[0061] The kit may include a heating device.

[0062] In particular, the heating device is adapted to allow heating of the composition used for test a) or test b), and in particular for test b), to a temperature between 70°C and 110°C, preferably between 90°C and 100°C.

[0063] Preferably, the heating is carried out by conduction.

[0064] The heating device can be configured to maintain a predefined heating temperature, in particular above 50°C, for at least 5 minutes.

[0065] The heating device can be configured so that the total heating time does not exceed 10 minutes, and for example be arranged to automatically stop the heating once a predefined time has elapsed. Lighting device

[0066] Preferably, the assembly includes a lighting or backlighting device. The lighting or backlighting device preferably has the form of a luminous base intended to serve as a support for the container, the latter being at least partially transparent or translucent.

[0067] The lighting or backlighting device may have an electrical power of at least 1 watt, preferably at least 1.5 watts. Container

[0068] The container in which the fibers 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 color of the hair fibers and / or the composition while leaving them in the container, and to allow possible backlighting of the composition and the hair present in the container.

[0069] This container may bear a mark, for example in the form of an engraving or a silkscreen, allowing the quantity of composition introduced at the time of the test to be measured. Sampling wand

[0070] The kit may include a wand for collecting the hair fibers to be tested.

[0071] The sampling rod may include a shaft extending along a longitudinal axis X and having in its distal part a slit extending substantially longitudinally so as to form at least a first branch and at least a second branch, the length of the first branch being less than the length of the second branch.

[0072] The second, longer arm allows the operator to select the hair fibers to be collected. Once the desired quantity of hair fibers has been selected, the operator can slide them into the slot so as to lock them between the first and second arms of the wand. Then, the operator can wrap the hair fibers around the first and second arms before finally cutting them.

[0073] The distal part of the stem may be beveled and / or truncated.

[0074] In addition, the rod may include a gauge extending transversely to the longitudinal axis X.

[0075] The gauge advantageously allows for a more precise estimation of the quantity of hair fibers to be extracted, thus enabling calibrated, rapid, and accurate fiber extraction. In particular, the extraction of hair fibers from a client's head of hair by a hairdresser is unpleasant for them. Therefore, it is essential to extract only the necessary, limited number of hair fibers. The presence of the gauge is particularly advantageous because it allows for the efficient extraction of the optimal quantity of hair fibers.

[0076] The gauge may be a hole, an annular groove, or a recess intended to receive capillary fibers. In particular, the gauge may form a V flush with the stem.

[0077] The wand may alternatively or additionally include a retaining element intended to hold the hair fibers to be taken from the stem.

[0078] Such a retaining element advantageously allows the collected hair fibers to be transported to the test container without loss, while avoiding, where appropriate, any direct contact between the operator and the collected hair fibers.

[0079] It may also be advantageous to be able to pack the hair fibers taken from the container and / or to be able to extract them from the container.

[0080] To this end, the rod may include an enlarged proximal portion, for example with a diameter greater than that of a median portion of the shaft. The enlarged portion may be formed by molding, cutting, or be an attached end piece.

[0081] The rod may alternatively or additionally include a hook at the proximal end of the rod.

[0082] The rod may have a length greater than 10 cm, and / or less than 20 cm, and preferably the length of the rod is between 13 cm and 17 cm, being for example approximately equal to 15 cm.

[0083] Preferably, the test kit includes packaging containing the container and the test composition (ready to use or in the form of ingredients to be mixed), optionally the sampling stick and / or a colorimetric reference such as a color chart.

[0084] The kit may include, where appropriate, the lighting or backlighting device and / or the heating device.

[0085] The kit advantageously comprises packaging in which the composition used for test a) or test b), and optionally the sampling wand and / or the colorimetric reference, are packaged. This packaging may also contain, where applicable, the lighting or backlighting device and / or the heating device. Hair treatment kit

[0086] The invention also relates to a hair treatment assembly, comprising: - at least one staining residue detection kit according to the invention, as defined above, and - at least one hair treatment composition contained in a separate container, the hair treatment composition preferably being a coloring composition.

[0087] This assembly can be packaged.

[0088] The assembly may include at least two hair treatment compositions, in two separate containers respectively, for example a first coloring composition suitable for carrying out coloring in the event of evidence of the presence of undesirable coloring residues, a second coloring composition suitable for coloring in the event of evidence of the presence of undesirable coloring residues.

[0089] The hair treatment composition(s) may include one or more of the following compositions: - at least one treatment composition suitable for the presence of unwanted hair color residues, and / or - at least one treatment composition suitable for the absence of undesirable color residues in the hair.

[0090] The treatment compositions can each be a coloring or bleaching composition. In particular, the treatment composition in the case of a positive detection of undesirable color residues can be a composition designed to achieve a darker color than the one previously colored by the individual. Otherwise, the presence of color residues will lead to colors different from those desired, or even an unsightly result. Brief description of the drawings

[0091] The invention will be better understood upon reading the detailed description that follows, the non-limiting examples of its implementation, and upon examination of the accompanying drawing, on which:

[0092] [Fig. 1] [Fig. 1] illustrates an example of a kit according to the invention, for detecting coloring residues in hair fibers,

[0093] [Fig.2] [Fig.2] illustrates an example of a treatment assembly comprising, among other things, a kit for detecting color residues in hair fibers,

[0094] [Fig.3] [Fig.3] illustrates steps of an example of a detection method according to the invention, and

[0095] [Fig.4] [Fig.4] illustrates steps of an example hair treatment process comprising the implementation, prior to treatment, of a process for highlighting undesirable color residues.

[0096] In the following description, identical elements or elements with analogous functions bear the same reference numeral. Their description is not repeated opposite each of the figures; only the main differences between the embodiments are mentioned. Detailed description

[0097] Fig. 1 schematically represents an example of kit 2 according to the invention, for highlighting color residues in hair fibers.

[0098] Fig. 2 represents a treatment set 3 comprising this kit 2 and one or more staining compositions 90a, 90b.

[0099] Kit 2 is preferably packaged in a 50 package, for example a cardboard box, just like the treatment set 3.

[0100] Kit 2 includes at least one composition 70 enabling test a) or b) of the detection method according to the invention, as defined above.

[0101] Composition 70 may thus include an oxidizing agent in the case of test a), for example hydrogen peroxide, and an extraction solvent in the case of test b), as detailed above.

[0102] Composition 70 is packaged in a container 71, which can serve as a container for the test, by receiving the hair fibers.

[0103] Kit 2 may also include, as illustrated, a hair fiber sampling wand 30 and a heating device 80, both shown schematically.

[0104] The heating device 80 is, for example, adapted to directly receive the container 71, into which capillary fibers to be tested have been introduced. Preferably, the heating device 80 is configured to heat the contents of the container 71 by conduction.

[0105] The container 71 is preferably at least partially transparent or translucent, so as to allow the colour of the composition and the tested hair fibres to be seen easily.

[0106] The detection method according to the invention may include, as illustrated in [Fig.3], a step 201 of sampling the hair fibers to be tested, preferably using the sampling wand 30, the selection and sampling of the fibers being carried out for example in the manner detailed above.

[0107] The hair fibers are then inserted into the container 71 containing the composition 70, so as to allow the composition 70 to come into contact with the hair fibers during a step 202.

[0108] Alternatively, the oxidation composition 70 is added to the container 71 after the hair fibers have been inserted into it. A visual marker 72 on the container 71 can indicate the volume of composition to be inserted into the container.

[0109] Composition 70 is preferably packaged in a quantity suitable for single use. Thus, composition 70 can be packaged in a small quantity, preferably in a volume less than 15 mL.

[0110] The container 71 containing the hair fibers in contact with the composition 70 can be placed in the heating device 80, in order to carry out a heating step 203 at a predefined temperature and for a predefined duration.

[0111] At step 204, the composition is removed from the heating device 80 to be placed under conditions allowing visual observation of the result of the test.

[0112] This visual observation may consist of determining the colour of composition 70 and / or hair fibres.

[0113] A colorimetric reference such as an N color chart can be used to help visually determine the observed color, this color chart comprising for example several flat areas of different hues and / or saturations C0, Cl, C2, C3, C4. These flat areas may have been printed, where appropriate, on the packaging of the test kit or on a separate leaflet.

[0114] This comparison can also be performed automatically, for example by image processing. An image of the color of 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; a mobile application is used to automatically determine whether the color obtained indicates the presence of color residues or not.

[0115] In a particular embodiment, the composition 70 is subjected after the test to a spectrophotometric analysis.

[0116] Where appropriate, an additive to better characterize the nature of the detected color residue(s) is introduced into the composition, as mentioned above. This additive may be packaged in a specific container, included in package 50.

[0117] The [Fig.4] is a block diagram representing steps of an example of a hair coloring process according to the invention.

[0118] This coloring process 300 may include a preliminary step 301 of collecting information on the hair to be treated, such as, for example, the starting color, the fragility of the hair, the texture, whether or not the hair is used in swimming pools, the use of Specific care, previous coloring applications, and the desired type of coloring can be taken into account when recommending the appropriate coloring treatment after the test has been performed.

[0119] The 300 coloring process then involves carrying out one of the tests a) and b) of the detection process according to the invention.

[0120] Depending on the result of the test, the assessment of the condition of the hair may possibly be refined in a step 302, taking into account the information received in step 301.

[0121] 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 coloring in step 303, or to apply an alternative coloring suitable for the condition of the hair in step 304, or to apply the desired coloring in step 305. Tests

[0122] Tests were carried out to observe the effectiveness of the process for highlighting colour residues according to the invention.

[0123] Several Mk k strands, ranging from 1 to 6, were colored according to the table below.

[0124] The Mk strands with k ranging from 1 to 2 were rinsed and dried with a hairdryer then stored for three days. The Mk strands, with k ranging from 3 to 6, were rinsed, shampooed, rinsed again, and then dried. All the strands were then washed ten times to remove the usual dye residue.

[0125] A bleaching treatment was then applied to a first section of each of the Mk strands to determine whether any residue present in each Mk strand would interfere with the bleaching process. This bleaching was carried out using L'Oréal Professionnel Blond Studio 8 bleaching powder, based on potassium and ammonium persulfates, sodium metasilicate, and magnesium carbonate, mixed before use with a 30-volume (9%) hydrogen peroxide-based formula in a mass ratio of 1:1.5. The bleaching mixture was applied at a rate of 10 g per 1 g of hair to a flat iron preheated to 33°C for 50 minutes. It was then rinsed under running water and the hair was shampooed. The color of the strands was observed after drying.

[0126] It has been considered that the residues alter the decolorization if the color obtained tends towards grey or if reflections different from the natural reflections, for example blue, green, red or violet reflections, are observed.

[0127] [Tables] Highlights MK Definition of highlights Type of color composition applied Bleaching may have occurred due to the presence of coloring residues Mj Strand composed of approximately 50% white hair and 50% brown hair with a tone level of 4. Coloring composition composed of 72% woad powder and 28% henna and containing an indigo precursor Yes m2 Strand composed of brown hair with a tone level of 4 Coloring composition composed of 72% woad powder and 28% henna and containing an indigo precursor Yes m3 Strand composed of approximately 50% white hair and 50% brown hair with a tone level of 4. Coloring cream based on fatty alcohols, non-ionic surfactants, fatty acids, ammonium hydroxide, monoethanolamine and pre-colorants hydroxyethoxy-aminopyrazolopyridine, 2-methyl-5-hydroxyethylaminophenol, 4-amino-2-hydroxytoluene, toluene-2,5-diamine and paraaminophen, the cream being mixed with a 20 volume hydrogen peroxide solution, in a mass ratio of cream / hydrogen peroxide of 1 to 1.5.Yes m4 Strand composed of brown hairs of tone height 6 Liquid colour composition based on fatty acid, glycols (propylene and hexylene glycols, glycerin), fatty alcohol and oxyethylenated fatty amides, aminom ethyl propanol and Basic Red 76 colour Yes. m5 Strand composed of approximately 90% white hair and 10% brown hair with a tone height of 4. Colouring cream based on fatty alcohols, cationic surfactant (Behentrimonium Chloride), Amodimethicone and HC Blue colour no. 15 and Basic Yellow 57 colourings marketed under the name Colourista shade Teal. Yes m6 Strand composed of approximately 90% white hair and 10% brown hair, shade level 4. Coloring cream based on fatty alcohols, non-ionic surfactants, ammonium hydroxy, monoethanolamine, and the pre-colorants paraphenylenediamine, resorcinol, 2,4-diaminophenoxyethanol, m-aminophenol, and hydroxybenzomorpholine, mixed with a 20-volume hydrogen peroxide solution in a cream / hydrogen peroxide mass ratio of 1 to 1.5. No

[0128] Two days after applying the hair color, a series of 10 non-conditioning shampoos is performed, with the hair being dried between each shampoo. This series of shampoos is useful for removing excess dye and corresponds to the normal shedding of this excess during the first few days or weeks after coloring. These shampoos do not remove all residues, particularly the most problematic ones.

[0129] The process for highlighting colour residues is implemented on a second part of each of the Mk strands.

[0130] Each second part of the Mk wicks was mixed, in a vial, with 10 mL of a Sk composition for carrying out test b), k ranging from 1 to 6, composed of 50 g of pentylene glycol, 49 g of water, and 1 g of monethanolamine. The vial was then heated for 7 minutes and 30 seconds at 95°C and then allowed to cool in air.

[0131] After cooling, the colors of the Sk compositions, respectively interacting with the second parts of the Mk wicks, were analyzed. Each Sk composition was observed under natural D65 light, and an ultraviolet-visible absorbance spectrum was obtained. The observed results are summarized in Table 2 below.

[0132] [Tables2] Composition; wick Absorbance peak (nm) Observed color S1M 557 Violet S2;M2 572 Gray S3;M3 489 Red S4;M4 502 Orange S5;M5 613 Yellow / green S6;M6 437 Beige

[0133] The colours observed for the Mi to M5 strands tested are problematic, which is confirmed by the bleaching tests carried out.

[0134] The colour observed at the end of the test of the M6 ​​strand is not problematic.

[0135] If a substantially colorless composition is observed, it could also be concluded that there is no problem.

[0136] Of course, the invention is not limited to the illustrated examples.

[0137] In particular, the formulation of the test compositions can be modified without departing from the scope of the present invention.

Claims

Demands

1. A method for detecting undesirable color residues in hair fibers, said method comprising at least one of the following tests: a) Contacting the hair fibers with an aqueous 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, this contact being carried out at a temperature above room temperature, or b) extracting color residues from the hair fibers, by contacting the hair fibers with at least one extraction solvent, at a temperature above room temperature, and observing any possible coloring of the composition following the interaction between the fibers and the composition.

2.

3. Method according to the preceding claim, comprising test a). Method according to claim 2, the composition comprising an oxidizing agent in a mass proportion of between 2 and 15% relative to the total weight of the composition.

4. A process according to any one of claims 2 and 3, the oxidizing agent being hydrogen peroxide.

5.

6. A method according to claim 1, comprising test b). A method according to claim 5, the extraction solvent being selected from polar, protic or aprotic solvents, in particular water or DMSO (dimethyl sulfoxide)

7. Process according to claim 5 or 6, the total mass content of extraction solvent(s) being between 50 and 100% relative to the total weight of the composition, and preferably between 70 and 90%.

8. A process according to any one of claims 5 to 7, the composition comprising a polyol, preferably a glycol, in particular propylene glycol, pentylene glycol or hexylene glycol, and preferably the polyol being pentylene glycol, the total mass content of polyol(s) relative to the total weight of the composition preferably ranging from 10% to 70%, more preferably from 40% to 60%

9. A method according to any one of claims 5 to 8, the composition comprising an alkali agent, preferably selected from amines, in particular an amine such as ammonia, triethylamine or triethanolamine, and preferably, the alkali agent is monoethanolamine.

10. A method according to any one of the preceding claims, comprising introducing the fibers into the composition and then heating the composition.

11. A method according to any one of the preceding claims, wherein the temperature of the composition during interaction with the fibers is greater than 50°C, and the maintenance of this temperature preferably lasts for at least 5 minutes.

12. A method according to any one of the preceding claims comprising determining the resulting colour of the composition with a colourimetric reference (N).

13. A process according to any one of the preceding claims, the colouring residues being residues of indigo, indigocarmine and / or chromatic azomethine-type dyes.

14. A method according to any one of the preceding claims, the composition used for test a) containing less than 10% by mass of persulfate(s), preferably being free of ammonium persulfate, in particular being free of any persulfate, and that for test b) being free of any oxidizing agent, in particular persulfates.

15. A method according to any one of claims 5 to 9, wherein in the case of test b), after a predetermined interaction time, at least one additive is added to the composition, this additive preferably being selected from dithionite, hydrogen chloride, ammonium persulfate, or hydrogen peroxide.

16. A method according to any one of the preceding claims, comprising a preliminary step of collecting hair fibers, in particular by means of a fiber collecting wand (30).

17. A hair coloring method comprising implementing a method for detecting coloring residues according to any one of the preceding claims, and then, depending on the result of the test, applying a coloring suitable for the presence or absence of residues.

18. A kit for detecting color residues in hair fibers, for carrying out the process according to any one of claims 1 to 16, comprising: - at least one oxidation composition (70) at alkaline pH comprising at least one oxidizing agent present in a content

19.

20.

21. comprising between 2 and 15% by weight relative to the total weight of the oxidation composition, packaged in a container with a volume 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. Kit according to claim 18, further comprising a fiber sampling wand (30). Kit according to one of claims 18 and 19, further comprising a heating device (80). A complete hair treatment kit, including: - at least one kit (2) for detecting staining residues according to any one of claims 18 to 20, and - at least one hair coloring composition, contained in a separate container.

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