Bronze ware distressing method

Abstract

The invention relates to the field of bronze ware, in particular to a bronze ware distressing method which comprises the following steps: S1, cleaning the surface of a bronze ware, uniformly coating the cleaned surface of the bronze ware with an etchant, and standing to obtain an oxidized bronze ware; s2, the surface of the oxidized bronze ware is washed until eluate is clear, then the whole oxidized bronze ware is soaked in a sodium bicarbonate solution for 24 h, the pH is 7.5-8, and the rusted bronze ware is obtained; s3, the rusted bronze ware is washed and dried, and the antique bronze ware is obtained; the corrosion inducing agent is at least one of silver nitrate, copper chloride and aspartic acid. According to the method, the surface of the bronze ware is eroded through the corrosion inducing agent, then the basic carbonate aerugo rust layer is formed on the erosion layer of the bronze ware through sodium bicarbonate induction, and finally the antique bronze ware is obtained through washing and drying, so that the antique effect of the surface of the bronze ware can be achieved within a short time; and uniform distribution of the antique layer on the surface of the bronze ware can be ensured.

Description

Technical Field

[0001] This application relates to the field of bronzes, and in particular to a method for aging bronzes. Background Technology

[0002] Bronze artifacts hold immense value in fields such as culture and art, historical research, and collecting. In the restoration of cultural relics, film and television production, and artistic creation, bronze artifacts are frequently subjected to an aging process to achieve a more realistic visual effect and recreate the historical atmosphere. This is of great significance for the inheritance and display of ancient culture. It allows people to more directly experience the charm of ancient civilization and promotes cultural exchange and dissemination.

[0003] In the process of aging bronze artifacts, traditional techniques include soaking them in chemical agents such as copper sulfate solution. The chemical reaction between copper and copper sulfate produces patina, mimicking the aging effect. Alternatively, acetic acid vapor is used to fumigate the surface of the bronze, causing a chemical reaction that creates an appearance similar to natural rust. However, traditional methods of aging bronze artifacts have significant drawbacks. Chemical soaking and fumigation can lead to uneven aging, unnatural patina color and morphology, and an inability to accurately simulate the realistic effects of erosion over time, failing to capture the complex rust formation that occurs naturally over extended periods. These methods are insufficient to meet the demands for highly realistic aging simulations of bronze artifacts in fields such as artifact restoration and artistic creation. Summary of the Invention

[0004] In order to improve the antique effect of bronzes, this application provides a method for aging bronzes.

[0005] This application provides a method for aging bronze artifacts, which employs the following technical solution: A method for aging bronze artifacts includes the following steps: S1: Clean the surface of the bronze artifact, and then evenly coat the cleaned bronze artifact with an oxidizing agent and let it stand to obtain an oxidized bronze artifact. S2: Rinse the surface of the oxidized bronze until the washing liquid is clear, then immerse the oxidized bronze in a sodium bicarbonate solution for 24 hours at pH 7.5-8 to obtain rusted bronze. S3: Wash and dry the rusted bronze artifacts to obtain antiqued bronze artifacts; The etchant is at least one of silver nitrate, acetic acid, and aspartic acid.

[0006] Preferably, the etchant is silver nitrate.

[0007] By adopting the above technical solution, the surface of the bronze is first cleaned to provide a clean base for the subsequent rust formation reaction. Then, an etchant is applied to the surface of the bronze to form an etched layer. The excess etchant is then washed off and the bronze is immersed in sodium bicarbonate. Sodium bicarbonate, as a rust-forming agent, can induce the formation of a green or blue-green basic copper carbonate rust layer on the etched layer. Finally, the rust layer on the surface of the bronze is stabilized by washing and drying, resulting in an aged bronze artifact.

[0008] Acetic acid provides a stable source of hydrogen ions, continuously dissolving the oxide film on the bronze surface, exposing the base metal, and maintaining a mild but continuous corrosion environment. Furthermore, acetate ions combine with dissolved copper ions to form basic copper acetate.

[0009] Aspartic acid, as an amino acid regulator, can chelate metal ions with its amino and carboxyl groups, and react with Cu on the bronze surface. 2+ And Cu that may precipitate from the alloy 2+ It forms a stable, water-soluble copper-aspartic acid complex, and the aspartic acid solution is weakly alkaline, providing a mild and relatively stable acidic environment.

[0010] Silver nitrate is a strong oxidizing agent, which provides Ag + Direct copper oxidation produces elemental silver, which can further react with oxygen in the air to form rust phases such as silver oxide and silver hydroxide. Simultaneously, Ag... + It can form a composite rust layer with the oxides on the substrate surface, creating a natural gradient color system on the surface of bronzes. It can restore the natural color characteristics of bronzes, which are "green with brown and brown with red". Therefore, silver nitrate is preferred as an etchant.

[0011] This application involves coating a clean bronze surface with an etchant, which then erodes the surface. Sodium bicarbonate is used as a rust-forming agent to induce the formation of a green or blue-green basic copper carbonate rust layer on the black copper oxide layer. Finally, washing and drying stabilize the rust layer on the bronze surface, resulting in an aged bronze artifact. Compared to traditional bronze aging processes, this application can achieve an antique effect on the bronze surface in a shorter time. Furthermore, the immersion method ensures a uniform distribution of the antique layer on the bronze surface, avoiding color differences.

[0012] Preferably, the etchant is a mixture of silver nitrate and aspartic acid.

[0013] Preferably, the mass ratio of silver nitrate to aspartic acid is 1:(0.5-1).

[0014] By employing the above technical solution, silver nitrate and aspartic acid are combined to form an etching agent. The amino and carboxyl groups in aspartic acid can react with the Ag ions released from the ionization of silver nitrate. + A coordination reaction occurs, forming [Ag(Asp)] 0 [Ag2(Asp)] 2+ In stable coordination compounds, the Ag in the coordination state... + The reduced activity of Ag results in a milder displacement reaction with the bronze substrate. Furthermore, some aspartic acid molecules bind to copper atoms on the substrate surface via coordination bonds, forming a "metal-amino acid" coordination protective film that chemically blocks Ag. + Excessive reaction with the matrix.

[0015] When the proportion of silver nitrate is too high, the coordinating ability of aspartic acid is insufficient, leading to the free Ag... + When the concentration of sodium bicarbonate is too high, the rate of displacement reaction with the bronze substrate is too fast. The resulting silver oxide rust layer is dense and hard, and its bonding force with the substrate is weak. During subsequent sodium bicarbonate post-treatment, carbonate ions cannot penetrate into the interior of the rust layer and cannot be fully converted into a stable carbonate rust phase, resulting in poor stability of the rust layer and easy detachment.

[0016] When the proportion of silver nitrate is too low, aspartic acid is in excess, and most of the Ag... + Free Ag is bound in a stable coordination compound by strong coordination. + If the concentration is too low, the rust layer will be "loose and flocculent". When stored for a long time, it will easily absorb moisture and dust from the air, resulting in "dampness and clumping". It also has poor friction resistance and the powdery rust will easily fall off with slight touch.

[0017] Preferably, the concentration of sodium bicarbonate is 1-3 wt%.

[0018] By adopting the above technical solution, when the concentration of sodium bicarbonate is too low, there are insufficient bicarbonate ions in the solution, which leads to a slow and incomplete conversion reaction of copper oxide to basic copper carbonate. The resulting product is light in color, loose in structure, and has poor adhesion, making it easy to fall off. When the concentration of sodium bicarbonate is too high, the reaction is too fast, resulting in coarse and loose basic copper carbonate crystals, forming a thick but brittle rust layer that is easy to powder and fall off, and may corrode the underlying copper oxide or even the bronze substrate.

[0019] Preferably, in S2, the immersion temperature of the bronze is 70-80℃.

[0020] By adopting the above technical solution, when the soaking temperature is too low, the reaction rate is slow, and it is difficult to fully convert copper oxide into basic copper carbonate within 24 hours, resulting in insufficient rust layer formation; when the soaking temperature is too high, the reaction is violent and out of control, and the generated basic copper carbonate crystals are large, loose and porous, making the rust layer very easy to fall off.

[0021] Preferably, in S3, after the rusted bronze artifact is washed and dried, a color-preserving coating is applied to its outer surface to obtain an antiqued bronze artifact; the color-preserving coating comprises 15-18% color-preserving agent and 82-85% diluent, wherein the color-preserving agent is at least one of cerium citrate and polyvinyl butyral, and the diluent is a mixture of ethanol and water.

[0022] By adopting the above technical solution, the color-preserving coating can form a dense protective film on the surface of the rust layer, which isolates the external environment from direct contact with the rust layer and reduces the probability of the rust layer being oxidized, hydrolyzed or corroded, thereby achieving long-term preservation of the color of the antique bronze.

[0023] The cerium ions in cerium citrate can form coordination bonds with the hydroxyl and carbonate ions in basic copper carbonate, "bridging" the dispersed rust particles into a continuous phase, preventing them from dissolving or decomposing in the environment. Furthermore, the citrate ions in cerium citrate can form six-membered chelates with copper ions through multiple oxygen atoms, reducing the chemical activity of copper ions and inhibiting their further oxidation into unstable high-valence compounds.

[0024] Polyvinyl butyral contains a large number of acetal groups and residual hydroxyl groups in its molecular chain structure. It can form a soft, dense, highly transparent and strongly adhesive physical barrier on the rust layer of bronze artifacts, effectively isolating environmental corrosive factors, thus allowing bronze artifacts to maintain their existing corrosion layer.

[0025] Preferably, the color-retaining agent is a mixture of cerium citrate and polyvinyl butyral.

[0026] By adopting the above technical solution, the molecular chain of polyvinyl butyral contains a large number of hydroxyl groups, and the cerium citrate molecule contains carboxyl and hydroxyl groups. The hydroxyl and carboxyl groups of both can form dense intermolecular hydrogen bonds, making the cerium citrate and polyvinyl butyral molecules tightly bound together. The Ce in cerium citrate... 3+ Cerium citrate can form weak coordination bonds with the hydroxyl groups on the polyvinyl butyral molecular chain, further strengthening the chemical bonding between the two. This also allows cerium citrate to be more uniformly dispersed in the polyvinyl butyral system, thereby improving the film density and adhesion. The Ce in cerium citrate... 3+ It has excellent antioxidant properties, can capture free radicals in the environment to inhibit the oxidative aging of polyvinyl butyral molecular chains, and improve the stability of the film.

[0027] Preferably, the mass ratio of cerium citrate and polyvinyl butyral is (0.3-1.2):1.

[0028] By adopting the above technical solution, when the proportion of cerium citrate is too high, polyvinyl butyral is insufficient, making it impossible to effectively fix the excess cerium citrate. Some cerium citrate exists in a free form, and the free cerium citrate cannot participate in film formation, resulting in poor film continuity and unsatisfactory color retention. When the proportion of cerium citrate is too low, cerium citrate cannot fill the micropores of polyvinyl butyral, resulting in insufficient film density, and the small amount of cerium citrate... 3+ The film's inadequate free radical scavenging ability leads to a decrease in film stability.

[0029] In summary, this application includes at least one of the following beneficial technical effects: 1. This application involves coating a clean bronze surface with an etchant, which then erodes the surface of the bronze. Sodium bicarbonate is used as a rust-forming agent to induce the formation of a green or blue-green basic copper carbonate rust layer on the black copper oxide layer. Finally, the rust layer on the bronze surface is stabilized through washing and drying, resulting in an aged bronze artifact. Compared with traditional bronze aging processes, this application can achieve an antique effect on the surface of bronze artifacts in a shorter time. Furthermore, the immersion method ensures that the antique layer on the surface of the bronze artifact is evenly distributed, avoiding color differences. 2. In this application, silver nitrate and aspartic acid are combined to form an etching agent. The amino and carboxyl groups in aspartic acid can react with the Ag released from the ionization of silver nitrate. + A coordination reaction occurs, forming [Ag(Asp)] 0 [Ag2(Asp)] 2+ In stable coordination compounds, the Ag in the coordination state... + The reduced activity of Ag results in a milder displacement reaction with the bronze substrate. Furthermore, some aspartic acid molecules bind to copper atoms on the substrate surface via coordination bonds, forming a "metal-amino acid" coordination protective film that chemically blocks Ag. + Excessive reaction with the matrix; 3. This application achieves the long-term preservation of the color of antique bronzes by applying a color-preserving coating that forms a dense protective film on the surface of the rust layer, isolating the external environment from direct contact with the rust layer, reducing the probability of the rust layer being oxidized, hydrolyzed or corroded. Detailed Implementation

[0030] The raw materials in this application include the following: Silver nitrate: Uses commercially available product with CAS number 7761-88-8; Copper chloride: Uses commercially available products with CAS number 10125-13-0; Aspartic acid: Uses commercially available products with CAS number 56-84-8; Fatty alcohol polyoxyethylene ether: a commercially available product with CAS number 52292-17-8; Polyvinylpyrrolidone: a commercially available product with CAS number 9003-39-8; Cerium citrate: selected from Inner Mongolia Zhongke Lanthanum Cerium Rare Materials Technology Co., Ltd. or Hubei Chengfeng Chemical Co., Ltd.; Polyvinyl butyral: a commercially available product with CAS number 148-65-2.

[0031] The present application will be further described in detail below with reference to embodiments and comparative examples.

[0032] Example 1 A method for aging bronze artifacts includes the following steps: S1: Clean the surface of the bronze artifact with clean water and a soft brush. After cleaning, rinse off the cleaning agent from the surface of the bronze artifact and then evenly coat the cleaned bronze artifact with 4wt% silver nitrate. Let it stand for 10 minutes to obtain the oxidized bronze artifact. S2: Rinse the surface of the oxidized bronze until the washing liquid is clear, then immerse the oxidized bronze in a 2wt% sodium bicarbonate solution for 24 hours at pH 7.5 and a immersion temperature of 75℃ to obtain the rusted bronze. S3: Wash the rusted bronze artifacts at 75℃ until the washing solution is neutral, and then place them in a ventilated place to air dry naturally to obtain the aged bronze artifacts. Example 2

[0033] Example 2 is based on the preparation method of Example 1, except that silver nitrate is replaced with an equal amount of acetic acid, while the other conditions remain unchanged. Example 3

[0034] Example 3 is based on the preparation method of Example 1, except that silver nitrate is replaced with an equal amount of aspartic acid, while the other conditions remain unchanged. Example 4

[0035] Example 4 is based on the preparation method of Example 1, but silver nitrate is replaced by an equal amount of a mixture of silver nitrate and aspartic acid, wherein the mass ratio of silver nitrate and aspartic acid is 1:0.8, and the other conditions remain unchanged.

[0036] Performance testing The rust layer of the bronze artifacts from Examples 1-4 above was analyzed using the following specific testing methods: 1. Adhesion Using a specialized grid applicator, draw a 5cm x 5cm grid pattern on the selected small area of ​​rust with uniform pressure and spacing. The scratches should penetrate the rust layer to the underlying metal. After gently sweeping the grid area five times along the diagonal with a soft brush, apply strong adhesive tape to the grid area and press firmly with your fingers to ensure complete contact. Then, quickly peel off the tape at a 90° or 180° angle and observe the rust layer peeling at the grid intersections. Quantitatively rate the rust layer according to the standard chart, where 5 is the best and 0 is the worst.

[0037] Color difference The color space of bronze patina was measured using the CIE 1976 color difference formula and its colorimetric system, CIE LAB. The geometric distance between two positions of the bronze patina in the CIE 1976 (L*, a*, b*) color space was calculated, i.e., the color difference ΔE*. △E*=[(△L*)²+(△a*)²+(△b*)²] 1 / 2 Where: △L*=L* 样品 -L* 标准 ; △a*=a* 样品 -a* 标准 ; △b*=b* 样品 -b* 标准 ; L* represents lightness; a* represents red / green coordinates; b* represents yellow / blue coordinates; the smaller the △E* value, the smaller the color difference.

[0038] Based on the above detection method, the test results of Examples 1-4 were obtained, as shown in Table 1 below.

[0039] Table 1 Performance Test Tables for Examples 1-4

[0040] Referring to Table 1, a comparison of Examples 1-3 shows that when silver nitrate is chosen as the single etching agent, the resulting bronze rust layer exhibits the best performance. This is likely because the metallic silver generated from the substitution of copper on the bronze surface by silver nitrate directly deposits on the bronze substrate. Its stable properties provide a dense and stable underlying layer for subsequent treatment with sodium bicarbonate solution to generate more complex rust products such as basic copper carbonate. Furthermore, Ag... + It can form a composite rust layer with the oxides on the substrate surface, creating a natural gradient color system on the surface of bronzes, and can restore the natural color characteristics of bronzes, which are "green with brown and brown with red".

[0041] Comparing Examples 1-3 and Example 4, it can be seen that when silver nitrate and aspartic acid are combined to form an etching agent, the resulting bronze rust layer exhibits superior performance. This may be because the amino and carboxyl groups in aspartic acid can react with the Ag ionized from silver nitrate. +A coordination reaction occurs, forming [Ag(Asp)] 0 [Ag2(Asp)] 2+ In stable coordination compounds, the Ag in the coordination state... + The reduced activity of Ag results in a milder displacement reaction with the bronze substrate. Furthermore, some aspartic acid molecules bind to copper atoms on the substrate surface via coordination bonds, forming a "metal-amino acid" coordination protective film that chemically blocks Ag. + Excessive reaction with the matrix.

[0042] Examples 5-8 Examples 5-8 are based on the preparation method of Example 4, but the mixing mass ratio of silver nitrate and aspartic acid is adjusted as shown in Table 2.

[0043] Performance testing The rust layer of the bronze artifacts from Examples 4-8 above was analyzed using the following specific testing methods: 1. Stability Using an ultra-soft brush with very light pressure, gently brush back and forth 10 times on a fixed area of ​​the bronze rust layer. Check if there are any adhering substances on the brush or cotton swab, and observe the tested area with a magnifying glass to see if there is obvious wear or fading of color. Among them, level 0 is the most stable and level 5 is the loosest.

[0044] Based on the above detection method, the test results of Examples 4-8 were obtained, as shown in Table 2 below.

[0045] Table 2. Mixed mass ratio of silver nitrate and aspartic acid in Examples 4-8 and their performance test results.

[0046] Referring to Table 2, and comparing Examples 4-8, it can be seen that when the mass ratio of silver nitrate to aspartic acid is in the range of 1:(0.5-1), especially when the mass ratio of silver nitrate to aspartic acid is 1:0.8, the performance of the resulting bronze rust layer is optimal. This may be because when the proportion of silver nitrate is too high, the coordination ability of aspartic acid is insufficient, leading to the free Ag. + When the concentration of silver nitrate is too high, the displacement reaction rate with the bronze substrate is too fast, resulting in a dense, hard shell-like silver oxide rust layer with weak adhesion to the substrate. During subsequent sodium bicarbonate post-treatment, carbonate ions cannot penetrate into the rust layer and cannot be fully converted into a stable carbonate rust phase, leading to poor rust layer stability and easy detachment. Conversely, when the proportion of silver nitrate is too low, aspartic acid is excessive, and most of the Ag... + Free Ag is bound in a stable coordination compound by strong coordination. +If the concentration is too low, the rust layer will be "loose and flocculent". When stored for a long time, it will easily absorb moisture and dust from the air, resulting in "dampness and clumping". It also has poor friction resistance and the powdery rust will easily fall off with slight touch.

[0047] Examples 9-12 Examples 9-12 are based on the preparation method of Example 1, but the concentration of sodium bicarbonate is adjusted as shown in Table 3.

[0048] The bronze rust layers from Examples 9-12 were subjected to the aforementioned performance tests, and the test results are shown in Table 3.

[0049] Table 3. Sodium bicarbonate concentration and performance test results for Examples 1 and 9-12.

[0050] Referring to Table 3, a comparison of Examples 1 and 9-12 shows that the bronze rust layer exhibits the best performance when the concentration of sodium bicarbonate is between 1-3 wt%, especially when the concentration is 2 wt%. This may be because when the concentration of sodium bicarbonate is too low, there are insufficient bicarbonate ions in the solution, resulting in a slow and incomplete conversion reaction of copper oxide to basic copper carbonate, producing a light-colored, loosely structured rust layer with poor adhesion that is easy to peel off. When the concentration of sodium bicarbonate is too high, the reaction is too fast, resulting in coarse and loose basic copper carbonate crystals, forming a thick but brittle rust layer that is easy to powder and peel off, and may even corrode the underlying copper oxide or even the bronze substrate.

[0051] Examples 13-16 Examples 13-16 are based on the preparation method of Example 1, but the immersion temperature of the bronze in S2 is adjusted, as shown in Table 4.

[0052] The bronze rust layers from Examples 13-16 were subjected to the aforementioned performance tests, and the test results are shown in Table 4.

[0053] Table 4 Immersion temperature and performance test results for Examples 1 and 13-16

[0054] Referring to Table 4, a comparison of Examples 1 and 13-16 shows that the bronze rust layer exhibits the best performance when the soaking temperature is in the range of 70-80℃, especially when the soaking temperature is 75℃. This may be because when the soaking temperature is too low, the reaction rate is slow, making it difficult to fully convert copper oxide into basic copper carbonate within 24 hours, resulting in insufficient rust layer formation. When the soaking temperature is too high, the reaction becomes violent and uncontrolled, and the generated basic copper carbonate crystals are large, loose, and porous, making the rust layer very easy to peel off.

[0055] Example 17 Example 17: Based on the preparation method of Example 1, in S3, after the rusted bronze artifact is washed and dried, a color-preserving coating is applied to its outer surface to obtain an antiqued bronze artifact; the color-preserving coating includes 16% color-preserving agent and 84% diluent, the color-preserving agent is cerium citrate, and the diluent is a mixture of ethanol and water, with the remaining conditions unchanged.

[0056] Example 18 Example 18 is based on the preparation method of Example 17, except that cerium citrate is replaced with an equal amount of polyvinyl butyral, while the other conditions remain unchanged.

[0057] Example 19 Example 19 is based on the preparation method of Example 17, but cerium citrate is replaced by an equal amount of a mixture of cerium citrate and polyvinyl butyral, wherein the mass ratio of cerium citrate to polyvinyl butyral is 0.8:1, and the other conditions remain unchanged.

[0058] Performance testing The rust layers of the bronze artifacts from Examples 1 and 17-19 were analyzed using the following specific testing methods: 1. Color retention and color difference The color space of the bronze patina was measured using the CIE 1976 color difference formula and its colorimetric system, CIE LAB. The geometric distance between two positions in the CIE 1976 (L*, a*, b*) color space before and after color preservation was calculated, i.e., the color difference ΔE*. Color retention △E*=[(△L*)²+(△a*)²+(△b*)²] 1 / 2 Where: △L*=L* 保色后 -L* 保色前 ; △a*=a* 保色后 -a* 保色前 ; △b*=b* 保色后 -b* 保色前 ; L* represents lightness; a* represents red / green coordinates; b* represents yellow / blue coordinates. The smaller the color retention ΔE* value, the smaller the color difference.

[0059] 2. Corrosion resistance The aged bronze samples were placed in a salt spray test chamber and sprayed continuously for 10 days with a 5wt% sodium chloride solution, pH 7, 35℃, and a salt spray deposition rate of 1mL / (h・80cm²). After cleaning the salt deposits on the surface of the aged bronze samples and drying them, the rust area and coating adhesion grade were tested.

[0060] Based on the above detection method, the test results of Examples 1 and 17-19 were obtained, as shown in Table 5 below.

[0061] Table 5. Color-retaining agents and their performance test results in Examples 1 and 17-19.

[0062] Referring to Table 5, a comparison of Example 1 and Examples 17-19 shows that the application of the color-preserving coating can form a dense protective film on the surface of the rust layer, isolating the external environment from direct contact with the rust layer, reducing the probability of the rust layer being oxidized, hydrolyzed or corroded, thereby achieving long-term preservation of the color of the antique bronze and effectively improving the adhesion of the rust layer to the bronze substrate.

[0063] Comparative Examples 17-19 show that the color-retaining agent obtained by compounding cerium citrate and polyvinyl butyral produces bronze artifacts with superior performance. This may be because the molecular chain of polyvinyl butyral contains a large number of hydroxyl groups, while the cerium citrate molecule contains carboxyl and hydroxyl groups. The hydroxyl and carboxyl groups of both can form dense intermolecular hydrogen bonds, resulting in a tight bond between the cerium citrate and polyvinyl butyral molecules. The Ce in cerium citrate... 3+ Cerium citrate can form weak coordination bonds with the hydroxyl groups on the polyvinyl butyral molecular chain, further strengthening the chemical bonding between the two. This also allows cerium citrate to be more uniformly dispersed in the polyvinyl butyral system, thereby improving the film density and adhesion. The Ce in cerium citrate... 3+ It has excellent antioxidant properties, can capture free radicals in the environment to inhibit the oxidative aging of polyvinyl butyral molecular chains, and improve the stability of the film.

[0064] Examples 20-23 Examples 20-23 are based on the preparation method of Example 19, but the mixing mass ratio of cerium citrate and polyvinyl butyral is adjusted as shown in Table 7.

[0065] The bronze rust layers from Examples 20-23 were subjected to the aforementioned performance tests, and the test results are shown in Table 6.

[0066] Table 6. Mixed mass ratio of cerium citrate and polyvinyl butyral in Examples 19-23 and their performance test results.

[0067] Referring to Table 6, comparative examples 19-23 show that the performance of the antiqued bronze artifacts is optimal when the mass ratio of cerium citrate to polyvinyl butyral is (0.3-1.2):1, especially when the mass ratio is 0.8:1. This may be because when the proportion of cerium citrate is too high, the polyvinyl butyral is insufficient, preventing the excess cerium citrate from being effectively fixed. Some cerium citrate exists in a free form, which cannot participate in film formation, resulting in poor film continuity and unsatisfactory color retention. When the proportion of cerium citrate is too low, it cannot fill the micropores of polyvinyl butyral, leading to insufficient film density. Furthermore, a small amount of cerium citrate... 3+ The film's inadequate free radical scavenging ability leads to a decrease in film stability.

[0068] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for aging bronze artifacts, characterized in that, Includes the following steps: S1: Clean the surface of the bronze artifact, and then evenly coat the cleaned bronze artifact with an etchant and let it stand to obtain an oxidized bronze artifact. S2: Rinse the surface of the oxidized bronze until the rinsing solution is clear, then immerse the oxidized bronze in a sodium bicarbonate solution for 24 hours at pH 7.5-8 to obtain rusted bronze. S3: Wash and dry the rusted bronze artifacts to obtain antiqued bronze artifacts; The etchant is at least one of silver nitrate, acetic acid, and aspartic acid.

2. The method for aging bronze artifacts according to claim 1, characterized in that, The etchant is silver nitrate.

3. The method for aging bronze artifacts according to claim 1, characterized in that, The etchant is a mixture of silver nitrate and aspartic acid.

4. The method for aging bronze artifacts according to claim 3, characterized in that, The mass ratio of silver nitrate and aspartic acid is 1:(0.5-1).

5. The method for aging bronze artifacts according to claim 1, characterized in that, The concentration of sodium bicarbonate is 1-3 wt%.

6. The method for aging bronze artifacts according to claim 1, characterized in that, In S2, the immersion temperature of bronze artifacts is 70-80℃.

7. The method for aging bronze artifacts according to claim 1, characterized in that, In S3, after the rusted bronze artifact is washed and dried, a color-preserving coating is applied to its outer surface to obtain an antiqued bronze artifact; the color-preserving coating includes 15-18% color-preserving agent and 82-85% diluent, wherein the color-preserving agent is at least one of cerium citrate and polyvinyl butyral, and the diluent is a mixture of ethanol and water.

8. The method for aging bronze artifacts according to claim 7, characterized in that, The color-retaining agent is a mixture of cerium citrate and polyvinyl butyral.

9. A method for aging bronze artifacts according to claim 8, characterized in that, The mass ratio of cerium citrate and polyvinyl butyral is (0.3-1.2):1.

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