Silverware brightener, its preparation method and application

Abstract

The application provides a silverware brightener and a preparation method and application thereof, and belongs to the technical field of silver product processing. The silverware brightener comprises 3.0-7.0 g / L of thiourea, 0.5-4.0 g / L of methanecarbimidine disulfide, 0.5-4.0 g / L of sodium lignosulfonate, 2.0-6.0 g / L of urea, a pH regulator and water, and the pH value is 1.0-3.0. Various substances in the application are bonded with each other to improve stability, and the sodium lignosulfonate enables the brightener to be evenly applied on the surface of the silverware. The thiourea can dissolve silver sulfide and other color spot substances and react with silver ions to form stable silver ion complexes. The methanecarbimidine disulfide can not only react with silver sulfide and other color spots, but also promote the reaction between the thiourea and the color spots. Meanwhile, the presence of the sodium lignosulfonate avoids the covering of passivation substances on the surface of the silverware, the penetration and damage of the silverware, and further improves the brightness of the silverware. The silverware brightener has simple components and can efficiently remove color spots.

Description

Technical Field

[0001] This invention relates to the field of silver product processing technology, and in particular to a silver polishing agent, its preparation method, and its application. Background Technology

[0002] Silver, with its alluring white luster, high chemical stability, and collectible and aesthetic value, is highly favored and widely used in jewelry, ornaments, silverware, tableware, congratulatory gifts, medals, and commemorative coins. Silver jewelry has a broad market in developing countries; silver tableware is popular in households; and exquisitely designed silver commemorative coins, with limited issuance, possess value preservation and appreciation potential, making them highly sought after by coin collectors and investors.

[0003] With the improvement of people's living standards and the rise of collecting, silverware has become increasingly popular. However, silverware such as silver coins (medals) and silver ornaments, which are exposed to the air for a long time, are prone to developing black or yellow spots on their surface, which gradually cover the entire surface of the silverware, affecting the appearance and ornamental value of the object and greatly reducing its collectible value.

[0004] The main component of black or yellow spots on the surface of silverware is silver sulfide, while it also contains small amounts of silver chloride, silver oxide, and other components. The discoloration of silverware affects the appearance and reflective properties of silver products. Therefore, the desulfurization of silverware and silver-plated products is a practical problem that urgently needs to be solved in the industrial silver products industry.

[0005] Patent application CN104593790A discloses a powder for removing stains from the surface of silverware. This powder is formulated from the following components in parts by weight: 1-15 parts thiourea; 1-15 parts citric acid; 1-15 parts tartaric acid; 1-3 parts disodium ethylenediaminetetraacetate; 1-15 parts sodium hypophosphite; 1-2 parts sodium hexametaphosphate; 0.1-0.2 parts sodium methylene dinaphthalenesulfonate; 0.01-0.02 parts benzotriazole; and 0.02-0.03 parts 2-mercaptobenzothiazole. While this powder has some effect on removing stains from the surface of silverware, its composition is relatively complex.

[0006] In view of this, it is necessary to design an improved silver polishing agent and its preparation method and application to solve the above problems. Summary of the Invention

[0007] The purpose of this invention is to provide a silver polishing agent, its preparation method, and its application. The agent is obtained by compounding thiourea, formamidine disulfide, urea, and sodium lignosulfonate and adjusting the pH. The various substances bond with each other, improving their stability. Sodium lignosulfonate allows the polishing agent to be applied more evenly to the surface of the silver. Thiourea then dissolves stains such as silver sulfide and reacts with silver ions to form a stable silver ion complex. Formamidine disulfide not only complexes with stains such as silver sulfide but also promotes the reaction between thiourea and the stains. Simultaneously, the presence of sodium lignosulfonate prevents passivating substances from penetrating and damaging the silver surface, further enhancing its brightness. Through the synergistic effect of these substances, the invention achieves the goal of quickly and efficiently removing stains from the surface of silver.

[0008] To achieve the above-mentioned objectives, the present invention provides a silver polishing agent comprising thiourea, formamidine disulfide, sodium lignosulfonate, urea, a pH adjuster, and water.

[0009] As a further improvement of the present invention, the concentration of thiourea in the silver polishing agent is 3.0-7.0 g / L, the concentration of formamidinium disulfide is 0.5-4.0 g / L, the concentration of sodium lignosulfonate is 0.5-4.0 g / L, and the concentration of urea is 2.0-6.0 g / L.

[0010] As a further improvement of the present invention, the pH value of the silver polishing agent is 1.0-3.0.

[0011] As a further improvement of the present invention, the pH adjuster includes one of citric acid, tartaric acid, and dilute sulfuric acid.

[0012] As a further improvement of the present invention, the water is deionized water.

[0013] The present invention also provides a method for preparing the above-mentioned silver polishing agent, wherein thiourea, formamidinium disulfide, sodium lignosulfonate and urea are added to water at a preset concentration, and after rapid stirring, a pH adjuster is added and stirring is continued to dissolve, so that the silver polishing agent reaches the preset pH value.

[0014] As a further improvement of the present invention, the rapid stirring time is 30-60s.

[0015] As a further improvement of the present invention, a pH adjuster is added and stirred for 5-10 minutes until dissolved, with the stirring speed being 400-600 r / min.

[0016] The present invention also provides an application of the above-mentioned silver polishing agent, wherein the silver polishing agent is evenly applied to the stained area and gently wiped to remove the stained area.

[0017] As a further improvement of the present invention, the wiping time is 1-5 minutes.

[0018] The beneficial effects of this invention are:

[0019] (1) The silver polishing agent provided by this invention is obtained by compounding thiourea, formamidine disulfide, urea, and sodium lignosulfonate and adjusting the pH. The various substances bond with each other to improve their stability. Sodium lignosulfonate can effectively improve the hydrophilicity of the silver surface, allowing the polishing agent to be better and more evenly applied to the silver surface. Then, thiourea dissolves the stains such as silver sulfide and reacts with silver ions to form a stable silver ion complex. At the same time, formamidine disulfide can not only react with the stains such as silver sulfide, but also promote the reaction between thiourea and the stains. The synergistic effect of thiourea and formamidine disulfide accelerates the removal of stains on the silver surface. In addition, sodium lignosulfonate causes the silver surface and passivating substances (such as the decomposition products of thiourea) to generate a negative charge, preventing these passivating substances from penetrating and damaging the silver surface, and further improving the brightness of the silver. Furthermore, formamidine disulfide can also play a certain protective role on the silver surface, reducing the silver from being oxidized again in a short time. This invention achieves the goal of quickly and efficiently removing stains from the surface of silverware through the synergistic effect of various substances.

[0020] (2) The silver polishing agent provided by this invention has a simple composition. Applying the polishing agent evenly to the stained area and gently wiping for 1-5 minutes quickly removes the stains from the silver surface. Furthermore, the silver polishing agent of this invention is cyanide-free, non-toxic, harmless, stable in performance, widely applicable, has a simple preparation process, low production cost, and is easy to use without damaging the silver surface, leaving it shiny and new. It is a method for the non-toxic and efficient removal of stains from silver surfaces, and has significant economic and social implications for environmental protection and comprehensive resource utilization in my country. Attached Figure Description

[0021] Figure 1 This is a photograph of a silver sheet with colored spots, as shown in Example 1.

[0022] Figure 2 This is a photograph of a silver sheet treated with the silver polishing agent prepared in Example 1. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] It should also be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and / or processing steps closely related to the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0025] Additionally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0026] This invention provides a silver polishing agent comprising thiourea, formamidine disulfide, sodium lignosulfonate, urea, a pH adjuster, and water.

[0027] The silver polish contains thiourea at a concentration of 3.0-7.0 g / L, formamidinium disulfide at a concentration of 0.5-4.0 g / L, sodium lignosulfonate at a concentration of 0.5-4.0 g / L, and urea at a concentration of 2.0-6.0 g / L; the pH value of the silver polish is 1.0-3.0.

[0028] pH adjusters include one of citric acid, tartaric acid, or dilute sulfuric acid.

[0029] The water is deionized.

[0030] Specifically, thiourea (SC(NH2)2) first dissolves in the solution. Then, the aqueous solution of thiourea dissolves the pigmented substances such as silver sulfide and reacts with the pigmented substances (mainly with the silver ions after the pigmented substances have dissolved) to form stable cationic complexes or silver ion complexes, thereby achieving the purpose of removing the pigmented substances such as silver sulfide. The specific reaction is as follows:

[0031] Ag + +2SC(NH2)2→Ag(SC(NH2)2)2 +

[0032] Formamidinium disulfide (S2C2(NH)2(NH2)2) can, on the one hand, undergo a complexation reaction with dissolved silver sulfide and other stains (mainly reacting with silver ions after the stains have dissolved), and on the other hand, it can act as an oxidizing agent, synergistically with thiourea, to accelerate the removal of stains from the surface of silverware. The specific reaction is as follows:

[0033] Ag + +SC(NH2)2+S2C2(NH)2(NH2)2+H + →Ag(SC(NH2)2)2 +

[0034] Sodium lignosulfonate, as a surfactant, effectively enhances the hydrophilicity of silver surfaces, making it easier for silver polishing agents to adhere during cleaning. Simultaneously, the sodium lignosulfonate molecular chain contains active groups such as phenolic hydroxyl and ether methyl groups. These groups generate a negative charge between the silver surface and passivating substances (such as products of thiourea decomposition). The mutual repulsion between these negative charges prevents these passivating substances from covering the silver surface, reducing the penetration and damage of harmful substances such as CN·NH2 and elemental sulfur, further enhancing the silver's luster.

[0035] The presence of urea can effectively inhibit the oxidative decomposition of thiourea, while providing more amino groups (-NH2) to the reaction system, further promoting the removal of stains such as silver sulfide.

[0036] The oxidative decomposition of thiourea proceeds as follows, ultimately producing passivating substances CN·NH2 and elemental S:

[0037] 2SC(NH2)2=(SCN2H3)2+2H + +2e - ,

[0038] (SCN2H3)2=SC(NH2)2+Sulfinic Compound,

[0039] Sulfinic Compound=CN·NH2+S 0

[0040] In summary, the principle behind this silver polishing agent's ability to remove stains is as follows: thiourea molecules contain amino active groups, formamidinium disulfide molecules contain amino and imino active groups, urea molecules contain amino and carbonyl active groups, and sodium lignosulfonate molecules contain phenolic hydroxyl and ether methyl groups. These different molecules bond with each other through hydrogen bonds, forming a relatively stable structure and improving the stability of each substance. Urea molecules have a similar structure to thiourea, making it easier for them to bond and thus improving the stability of thiourea. Sodium lignosulfonate effectively enhances the hydrophilicity of silver surfaces, allowing the polishing agent to be applied more evenly. Thiourea then dissolves discoloration substances such as silver sulfide and reacts with silver ions to form stable silver ion complexes. Simultaneously, formamide disulfide not only complexes with silver sulfide and other discoloration substances but also promotes the reaction between thiourea and these substances, accelerating the removal of discoloration from the silver surface through the synergistic effect of thiourea and formamide disulfide. Furthermore, sodium lignosulfonate imparts a negative charge to the silver surface and passivating substances (such as products of thiourea decomposition), preventing these substances from penetrating and damaging the silver, further enhancing its shine. Moreover, formamide disulfide also provides some protection to the silver surface, reducing the risk of re-oxidation in a short period.

[0041] This invention also provides a method for preparing a silver polishing agent. Thiourea, formamidinium disulfide, sodium lignosulfonate, and urea are added to water at a preset concentration. After rapid stirring for 30-60 seconds, a pH adjuster is added, and stirring continues for 5-10 minutes at a stirring speed of 400-600 rpm until dissolved, bringing the silver polishing agent to the preset pH value. This rapid addition of the pH adjuster ensures greater stability of the components in the polishing agent.

[0042] The present invention also provides an application of the silver polishing agent, wherein the silver polishing agent is evenly applied to the stained area and gently wiped for 1-5 minutes to remove the stained area.

[0043] The present invention will now be described in detail through specific embodiments.

[0044] Example 1

[0045] A method for preparing a silver polishing agent involves adding thiourea, formamidinium disulfide, sodium lignosulfonate, and urea to water at preset concentrations, stirring rapidly for 45 seconds, then adding citric acid, and continuing stirring at 600 rpm for 5 minutes until dissolved, thus adjusting the pH of the silver polishing agent to 1.5. The concentrations of thiourea, formamidinium disulfide, sodium lignosulfonate, and urea are as follows: 4.0 g / L, 3.5 g / L, 1.5 g / L, and 3.0 g / L.

[0046] Using a silver sheet with colored spots as a sample (e.g.) Figure 1 As shown, 5 parallel tests were conducted. A small amount of the obtained silver polish was applied evenly to the stained area with a soft cloth and gently wiped for about 4 minutes. The stained area was completely removed, and the silver was as shiny as new. Figure 2 As shown in the image, there are no signs of corrosion on the surface.

[0047] Example 2

[0048] A method for preparing a silver polishing agent involves adding thiourea, formamidinium disulfide, sodium lignosulfonate, and urea to water at preset concentrations, stirring rapidly for 45 seconds, then adding citric acid, and continuing stirring at 500 rpm for 7 minutes until dissolved, thus adjusting the pH of the silver polishing agent to 2.0. The concentrations of thiourea, formamidinium disulfide, sodium lignosulfonate, and urea are as follows: 6.0 g / L, 3.5 g / L, 1.5 g / L, and 4.0 g / L.

[0049] Using a silver sheet with discolored spots as a sample, take a small amount of the obtained silver polishing agent, apply it evenly to the discolored area with a soft cloth, and gently wipe for about 2 minutes. The discolored spots will be completely removed, and the silver sheet will be as bright as new with no traces of corrosion on the surface.

[0050] Example 3

[0051] A method for preparing a silver polishing agent involves adding thiourea, formamidinium disulfide, sodium lignosulfonate, and urea to water at preset concentrations, stirring rapidly for 45 seconds, then adding citric acid, and continuing stirring at 400 rpm for 10 minutes until dissolved, thus adjusting the pH of the silver polishing agent to 3.0. The concentrations of thiourea, formamidinium disulfide, sodium lignosulfonate, and urea are as follows: 7.0 g / L, 3.5 g / L, 1.5 g / L, and 5.0 g / L.

[0052] Using a silver sheet with discolored spots as a sample, take a small amount of the obtained silver polishing agent, apply it evenly to the discolored area with a soft cloth, and gently wipe for about 1 minute. The discolored spots will be completely removed, and the silver sheet will be as bright as new with no traces of corrosion on the surface.

[0053] As can be seen from Examples 1-3, the efficiency of silver polishing agent in removing stains increases with the increase of thiourea concentration and urea concentration. This may be because, on the one hand, urea and thiourea with matching concentrations are stably bonded, thereby improving the stability of thiourea, and on the other hand, urea provides more amino groups in the reaction system, further promoting the removal of stains such as silver sulfide.

[0054] Example 4

[0055] A method for preparing a silver polishing agent differs from Example 1 in that the concentration of formamidinium disulfide is 4.0 g / L. The rest is largely the same as in Example 1 and will not be repeated here.

[0056] Using a silver sheet with discolored spots as a sample, take a small amount of the obtained silver polishing agent, apply it evenly to the discolored area with a soft cloth, and gently wipe for about 1 minute. The discolored spots will be completely removed, and the silver sheet will be as bright as new with no traces of corrosion on the surface.

[0057] Comparative Example 1

[0058] A method for preparing a silver polishing agent differs from Example 1 in that the concentration of formamidinium disulfide is 0 g / L, while the rest is largely the same as in Example 1 and will not be repeated here.

[0059] Using a silver sheet with discolored spots as a sample, a small amount of the prepared silver polish was applied evenly to the discolored area with a soft cloth and gently wiped for about 15 minutes. Discoloration remained, and scratches and corrosion marks were visible on the surface. As shown in Comparative Example 1, the effect of removing discoloration was significantly reduced when formamidine disulfide was not added. This may be because without formamidine disulfide, the silver polish could not effectively complex with the discoloration caused by silver sulfide, further illustrating the synergistic effect of formamidine disulfide and thiourea.

[0060] Comparative Example 2

[0061] A method for preparing a silver polishing agent differs from Example 1 in that the concentration of formamidinium disulfide is 5.0 g / L. The rest is largely the same as in Example 1 and will not be repeated here.

[0062] Using a silver sheet with discolored spots as a sample, a small amount of the prepared silver polish was applied evenly to the discolored areas with a soft cloth and gently wiped for about 5 minutes. The discolored spots were completely removed, and the silver sheet was as shiny as new with no traces of corrosion on the surface. As shown in Comparative Example 2, the synergistic effect of various substances in the silver polish can only be better achieved when the amount of formamidinium disulfide is within a certain range.

[0063] Example 5

[0064] A method for preparing a silver polishing agent differs from Example 1 in that the concentration of sodium lignosulfonate is 4.0 g / L. The rest is largely the same as in Example 1 and will not be repeated here.

[0065] Using a silver sheet with discolored spots as a sample, take a small amount of the obtained silver polishing agent, apply it evenly to the discolored area with a soft cloth, and gently wipe for about 1 minute. The discolored spots will be completely removed, and the silver sheet will be as bright as new with no traces of corrosion on the surface.

[0066] Comparative Example 3

[0067] A method for preparing a silver polishing agent differs from Example 1 in that the concentration of sodium lignosulfonate is 0 g / L, while the rest is largely the same as in Example 1 and will not be repeated here.

[0068] Using a silver sheet with discolored spots as a sample, take a small amount of the obtained silver polishing agent, apply it evenly to the discolored area with a soft cloth, and gently wipe it for about 10 minutes. The discolored spots will still remain, and there will be scratches and corrosion marks on the surface.

[0069] Comparative Example 4

[0070] A method for preparing a silver polishing agent differs from Example 1 in that the concentration of sodium lignosulfonate is 5.0 g / L. The rest is largely the same as in Example 1 and will not be repeated here.

[0071] Using a silver sheet with discolored spots as a sample, take a small amount of the prepared silver polishing agent, apply it evenly to the discolored area with a soft cloth, and gently wipe for about 5 minutes. The discolored spots will be completely removed, and the silver sheet will be as bright as new with no traces of corrosion on the surface.

[0072] As can be seen from the data of Example 5 and Comparative Examples 1-3, sodium lignosulfonate needs to be controlled within a certain concentration range in order to achieve a better effect in removing pigmentation spots.

[0073] Comparative Example 5

[0074] A method for preparing a silver polishing agent differs from Example 1 in that the concentration of thiourea is 0 g / L, while the rest is largely the same as in Example 1 and will not be repeated here.

[0075] Using a silver sheet with discolored spots as a sample, a small amount of the prepared silver polishing agent was applied evenly to the discolored area with a soft cloth and gently wiped for about 15 minutes. Discoloration remained, and scratches and corrosion marks were visible on the surface. Comparative Example 5 shows that the effect of removing discoloration was significantly reduced when thiourea was not added. This may be because, without thiourea, firstly, discoloration substances such as silver sulfide are difficult to dissolve, and secondly, formamidinium disulfide alone cannot effectively complex with discoloration substances such as silver sulfide.

[0076] Comparative Example 6

[0077] A method for preparing a silver polishing agent differs from Example 1 in that the concentration of urea is 0 g / L, while the rest is largely the same as in Example 1 and will not be repeated here.

[0078] Using a silver sheet with discolored spots as a sample, a small amount of the prepared silver polish was applied evenly to the discolored area with a soft cloth and gently wiped for about 10 minutes. Discoloration remained, and scratches and corrosion marks were visible on the surface. As shown in Comparative Example 6, the effect of removing discoloration was significantly reduced when urea was not added. This may be because the absence of urea affects both the stability of thiourea and its complexation with the discoloration.

[0079] Comparative Examples 1, 3, and 5-6 demonstrate that only the synergistic effect of thiourea, formamidinium disulfide, sodium lignosulfonate, and urea can achieve a better spot-removing effect.

[0080] Comparative Example 7

[0081] A method for preparing a silver polishing agent differs from Example 1 in that thiourea is replaced with methylthiourea. Otherwise, it is largely the same as Example 1 and will not be described in detail here.

[0082] Using a silver piece with blemishes as a sample, take a small amount of the prepared silver polish, apply it evenly to the blemishes with a soft cloth, and gently wipe for about 15 minutes. The blemishes will be mostly removed.

[0083] Comparative Example 8

[0084] A method for preparing a silver polishing agent differs from Example 1 in that formamidine disulfide is replaced with potassium permanganate as a strong oxidizing agent. Otherwise, it is largely the same as Example 1 and will not be described in detail here.

[0085] Using a silver sheet with blemishes as a sample, take a small amount of the obtained silver polishing agent, apply it evenly to the blemishes with a soft cloth and gently wipe for about 10 minutes. The blemishes will still remain; extend the time to about 15 minutes, and the blemishes will be basically removed.

[0086] Comparative Example 9

[0087] A method for preparing a silver polishing agent differs from Example 1 in that sodium lignosulfonate is replaced with sodium methylene dinaphthalenesulfonate. Otherwise, it is largely the same as Example 1 and will not be described in detail here.

[0088] Using a silver sheet with blemishes as a sample, take a small amount of the obtained silver polishing agent, apply it evenly to the blemishes with a soft cloth, and gently wipe for about 10 minutes. The blemishes will be mostly removed, leaving only slight traces of blemishes.

[0089] The data from Comparative Examples 7-9 show that even if thiourea, formamidine disulfide, and sodium lignosulfonate are replaced with substances that have the same effect or similar structures, their ability to remove pigmentation is still relatively poor. This further illustrates that only the synergistic effect of thiourea, formamidine disulfide, sodium lignosulfonate, and urea can achieve a better effect in removing pigmentation.

[0090] In summary, this invention provides a silver polishing agent, its preparation method, and its application. It is obtained by compounding thiourea, formamidine disulfide, urea, and sodium lignosulfonate and adjusting the pH. The various substances bond together, improving their stability. Sodium lignosulfonate allows the polishing agent to be applied more evenly to the silver surface. Thiourea then dissolves discoloration substances such as silver sulfide and reacts with silver ions to form a stable silver ion complex. Formamidine disulfide not only complexes with discoloration substances like silver sulfide but also promotes the reaction between thiourea and the discoloration. Simultaneously, the presence of sodium lignosulfonate prevents passivating substances from penetrating and damaging the silver surface, further enhancing its shine. The silver polishing agent of this invention has simple components, is cyanide-free and non-toxic, has stable performance, wide applicability, is easy to operate, and is low in cost. Applying the polishing agent evenly to the discoloration area and gently wiping for 1-5 minutes quickly removes discoloration from the silver surface without damaging it, leaving the silver surface shiny and new.

[0091] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A silver polishing agent, characterized in that, Including thiourea, formamidine disulfide, sodium lignosulfonate, urea, pH adjuster and water; The silver polishing agent contains thiourea at a concentration of 3.0-7.0 g / L, formamidinium disulfide at a concentration of 0.5-4.0 g / L, sodium lignosulfonate at a concentration of 0.5-4.0 g / L, and urea at a concentration of 2.0-6.0 g / L. The pH value of the silver polishing agent is 1.0-3.

0.

2. The silver polishing agent according to claim 1, characterized in that, The pH adjuster includes one of citric acid, tartaric acid, and dilute sulfuric acid.

3. The silver polishing agent according to claim 1, characterized in that, The water is deionized water.

4. A method for preparing the silver polishing agent according to any one of claims 1 to 3, characterized in that, Thiourea, formamidinium disulfide, sodium lignosulfonate, and urea are added to water at a preset concentration. After rapid stirring, a pH adjuster is added, and stirring is continued to dissolve the mixture, so that the silver polishing agent reaches the preset pH value.

5. The method for preparing the silver polishing agent according to claim 4, characterized in that, The rapid stirring time is 30-60 seconds.

6. The method for preparing the silver polishing agent according to claim 4, characterized in that, Add pH adjuster and stir for 5-10 minutes until dissolved, at a stirring speed of 400-600 r / min.

7. The application of a silver polishing agent prepared by the method of any one of claims 1 to 3 or any one of claims 4 to 6, characterized in that, Apply the silver polish evenly to the stained area and gently wipe to remove the stain.

8. The application of the silver polishing agent according to claim 7, characterized in that, The wiping time is 1-5 minutes.

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