A method for preparing a tangka by combining porcelain drawing process

Abstract

The present application relates to the field of combination of ceramic technology and traditional art, and discloses a preparation method of Thangka combined with porcelain drawing technology, comprising the following steps: surface hydroxylation treatment is performed on the blank, and the surface hydroxyl of the blank is introduced and activated; modified frankincense oil is prepared, silane coupling agent and nanoparticles are added into the frankincense oil, and the adhesion and physical stability of the frankincense oil are enhanced through chemical modification; the modified frankincense oil is uniformly coated on the surface of the blank and dried and placed to form a stable bonding layer; a line drawing is drawn on the bonding layer, and a pattern design is completed by smearing enamel or new color pigments; the pigments and the bonding layer are solidified through multiple high-temperature firing, and the color of the golden pigment is protected through low-temperature firing; and finally, natural cooling is performed to obtain the Thangka. The present application has simple process and strong controllability, can significantly improve the artistic expressiveness and long-term preservation performance of the Thangka, and is suitable for industrial production and protection and inheritance of traditional Thangka art.

Description

Technical Field

[0001] This invention relates to the field of ceramic technology and traditional art, specifically a method for preparing Thangka paintings that combines ceramic painting techniques. Background Technology

[0002] Thangka painting typically involves complex painting and craft techniques. However, traditional Thangkas often use cloth or paper as their medium, which are prone to aging, cracking, or fading during long-term storage and in environments with high humidity and temperature, thus damaging the artwork's artistic expression and cultural value. To overcome these problems, porcelain painting techniques have gradually been introduced into Thangka production. Utilizing the high hardness and durability of porcelain, the exquisite details and color effects of the Thangka designs can be preserved for a long time.

[0003] Current Thangka painting techniques, which combine traditional porcelain painting methods, typically involve directly applying pigments to the surface of the porcelain blank and then firing it. However, due to the smooth and inactive surface of the porcelain blank, the pigments are difficult to adhere firmly, easily resulting in problems such as peeling off or uneven coloring during firing. Furthermore, traditional adhesion layers, such as resins or ordinary colloids, are prone to decomposition or flow under high temperatures, leading to distortion or insufficient durability of the fired design. Simultaneously, the interfacial bonding between the pigment layer and the porcelain blank is weak, making it difficult to meet the high-precision and multi-layered color expression requirements of complex Thangka designs.

[0004] Therefore, existing technologies still have significant shortcomings in terms of porcelain blank surface treatment, adhesion layer modification, and improvement of pattern color expression. There is an urgent need for a technical method that can enhance the adhesion performance of the porcelain blank surface, improve pigment bonding stability, and optimize color expression to better adapt to the artistic characteristics and long-term preservation requirements of Thangka. This invention addresses the deficiencies of the existing technologies by proposing a Thangka preparation method that combines porcelain painting techniques, aiming to improve the overall production quality of Thangka through a series of innovative processes. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for preparing Thangka paintings that incorporates porcelain painting techniques, thereby solving the problems of insufficient adhesion to the porcelain surface, poor pigment bonding stability, and limited color expression in existing Thangka painting processes that combine porcelain painting techniques.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing Thangka paintings using porcelain painting techniques, comprising the following steps:

[0007] 1) Surface hydroxylation treatment of the preform includes immersing the preform in a dilute acid solution to remove surface impurities and introduce hydroxyl groups, followed by high-temperature heat treatment to activate the hydroxyl groups.

[0008] 2) Preparation of modified frankincense oil, including adding silane coupling agent and nanoparticles to frankincense oil, dispersing them evenly and then allowing them to stand and mature;

[0009] 3) The modified frankincense oil is evenly coated on the surface of the hydroxylated embryo and then dried and left to stand to form a stable bonding layer.

[0010] 4) Draw a line drawing on the surface of the unpainted body coated with frankincense oil, and then apply pigments to complete the pattern design;

[0011] 5) The pattern is fired, with at least one initial firing and an optional second firing, to fix the pattern and colors;

[0012] 6) After firing, the Thangka is naturally cooled to obtain the finished product.

[0013] Preferably, the dilute acid solution in the hydroxylation treatment is a 0.5% to 1.5% nitric acid solution or acetic acid solution, and the soaking time is 3 to 5 minutes; the high-temperature heat treatment temperature is 400 to 450°C, and the duration is 2 to 3 hours.

[0014] Preferably, the silane coupling agent added to the frankincense oil is 3% to 5% of 3-aminopropyltriethoxysilane, and the nanoparticles are 0.5% to 1% of silicon dioxide or aluminum oxide with a particle size of 10 to 50 nm.

[0015] Preferably, the coating thickness of the modified frankincense oil is 50-100 μm, and after coating, it is dried at a low temperature of 50-60°C for 10-15 minutes.

[0016] Preferably, the line drawing is done using black pigment, which is iron oxide or copper oxide, and the pigment is evenly coated on the surface of the frankincense oil bonding layer.

[0017] Preferably, the initial firing temperature is 800°C and the duration is 6-8 hours, and the refiring temperature is 800-850°C and the duration is 4-6 hours.

[0018] Preferably, in the method, if it is necessary to add a gold part to the pattern, gold pigment is applied and a final low-temperature firing is carried out at a temperature of 600-700°C for 2-3 hours.

[0019] Preferably, the cooling method is natural cooling to room temperature, and the cooling time is 6 to 8 hours.

[0020] The present invention also provides a Thangka combining porcelain painting techniques prepared by the method described above.

[0021] This invention provides a method for preparing Thangka paintings that combines porcelain painting techniques. It has the following beneficial effects:

[0022] 1. This invention removes surface impurities and activates surface hydroxyl groups by hydroxylating the raw embryo, giving it a highly active chemical bonding ability. High-temperature heat treatment further enhances the activity of the raw embryo surface, providing stable reaction sites for the bonding of modified frankincense oil to the raw embryo surface, thereby significantly improving the adhesion of the coating layer.

[0023] 2. The modification of frankincense oil in this invention employs a combination of silane coupling agents and nanoparticles. The introduction of chemical bonds achieves a strong bond between the frankincense oil and the raw material, while the filling effect of the nanoparticles enhances the mechanical strength and heat resistance of the frankincense oil layer. This modification effectively solves the problems of easy decomposition or insufficient adhesion of traditional frankincense oil coatings during high-temperature firing.

[0024] 3. This invention allows for the creation of patterns on a modified frankincense oil bonding layer, enabling the pigments to adhere well to the frankincense oil and effectively preventing pigment flow or delamination during line drawing and coloring processes. Multiple gradient application techniques further enhance the pattern's depth and color expressiveness, while maintaining color saturation and uniformity after high-temperature firing.

[0025] 4. This invention employs a multi-firing process to gradually solidify the pigment and frankincense oil bond layer, making it less prone to decomposition or flow at high temperatures. The first firing fixes the pattern, the second firing adjusts the color layers, and the final low-temperature firing protects the gold pigment, ensuring the overall stability and detail clarity of the pattern and avoiding distortion or cracking that may be caused by a single high-temperature firing. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the method flow of the present invention. Detailed Implementation

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Please see the appendix Figure 1 This invention provides a method for preparing Thangka paintings that combines porcelain painting techniques, aiming to improve the adhesion, color expression, and durability of Thangka patterns by optimizing the surface treatment of the porcelain blank and modifying it with frankincense oil.

[0029] The method for preparing Thangkas that combines porcelain painting techniques may include the following steps:

[0030] S1. Perform surface hydroxylation treatment on the embryo;

[0031] S2. Preparation of modified frankincense oil;

[0032] S3. Apply modified frankincense oil to the surface of the raw embryo;

[0033] S4. Draw a line drawing on the surface of the unpainted blank, and then apply paint to it to complete the pattern design;

[0034] S5. Fire the pattern.

[0035] S6. After firing, the Thangka is cooled to obtain the finished product.

[0036] The specific implementation methods of each step of the method of the present invention will be described in detail below.

[0037] For step S1, in this embodiment, a suitable unglazed porcelain blank is first selected to meet the process requirements of the present invention. The unglazed porcelain blank is an unglazed porcelain blank with a smooth surface, no cracks, and a thickness of 3-6 mm to ensure that the coating and firing steps in the subsequent process can be carried out smoothly.

[0038] In this embodiment, to improve the surface activity of the pre-embedded embryo and enhance its adhesion to the frankincense oil binding layer, the pre-embedded embryo undergoes surface hydroxylation treatment. Specifically, this includes the following steps:

[0039] In this embodiment, the raw embryo is first immersed in a dilute acid solution for surface cleaning. The dilute acid solution is selected as a 0.5% to 1.5% nitric acid solution or acetic acid solution to remove impurities and contaminants that may exist on the surface of the raw embryo, including dust, trace metal ions, and other impurities that are not conducive to the subsequent adhesion of the bonding layer.

[0040] In this embodiment, the embryo is immersed in a dilute acid solution for 3 to 5 minutes. During the immersion process, the acid chemically corrodes the unstable substances on the surface of the embryo through contact with it, thereby exposing the active silica groups inside the embryo. Simultaneously, the concentration of the acid and the treatment time must be strictly controlled to avoid excessive corrosion that could damage the surface structure of the embryo.

[0041] In this embodiment, after pickling, the raw embryo is rinsed multiple times with distilled water until the pH of the surface solution returns to neutral (approximately pH 7). This step is to thoroughly remove residual acid to avoid adverse effects on subsequent frankincense oil coating.

[0042] After completing the pickling and rinsing processes described above, the raw embryo is subjected to high-temperature heat treatment in this embodiment. The pickled raw embryo is placed in a heat treatment furnace and heated at 400–450°C for 2–3 hours. Under high-temperature conditions, the activity of the silica groups on the surface of the raw embryo is further activated, and abundant hydroxyl groups (-OH) are formed on the surface, providing necessary reaction sites for the subsequent chemical bonding of frankincense oil.

[0043] In this embodiment, after high-temperature heat treatment, the green blank is naturally cooled to room temperature to avoid cracks or surface stress caused by rapid cooling, while maintaining the integrity of the surface hydroxyl groups.

[0044] This process gives the surface of the unglazed embryo a highly active hydroxylated structure, which significantly improves the adhesion of the frankincense oil binding layer, laying the foundation for subsequent coating, painting, and firing steps.

[0045] For step S2, in this embodiment, to improve the adhesion of frankincense oil to the surface of the raw embryo and enhance its adhesion to pigments, a modification process is used to treat the frankincense oil. The preparation process of modified frankincense oil includes the introduction of a silane coupling agent and the addition of nanoparticles, thereby giving the frankincense oil chemical bonding and interface enhancement functions.

[0046] In this embodiment, the frankincense oil selected is natural frankincense oil with a purity of ≥95%, which has good fluidity and high temperature stability, providing basic adhesion ability for the bonding layer.

[0047] In this embodiment, a silane coupling agent is added to the frankincense oil to enhance its chemical bonding with the surface of the raw frankincense. The silane coupling agent is 3-aminopropyltriethoxysilane (KH550), and its addition amount is 3% to 5% of the volume of the frankincense oil. The silane coupling agent is evenly dispersed in the frankincense oil by stirring, so that its active functional groups can be fully exposed, providing conditions for subsequent chemical reactions.

[0048] During the stirring process, a magnetic stirrer was used in this embodiment to stir at a speed of 300-500 rpm for 10-15 minutes to ensure that the silane coupling agent and frankincense oil molecules form a preliminary physical bond.

[0049] In this embodiment, to further enhance the mechanical properties and high-temperature stability of frankincense oil, nanoparticles are added to the above mixture. The nanoparticles are silicon dioxide (SiO2) or aluminum oxide (Al2O3), with a particle size ranging from 10 to 50 nm, and the addition amount is 0.5% to 1% of the volume of frankincense oil. The introduction of nanoparticles effectively improves the physical stability of frankincense oil through filling and interface strengthening effects.

[0050] To ensure uniform dispersion of nanoparticles in frankincense oil, a high-speed disperser was used in this embodiment, with a dispersion speed of 2000–3000 rpm and a dispersion time of 5–10 minutes. After the dispersion process, the uniformity of the frankincense oil mixture was checked to ensure that no obvious agglomeration of nanoparticles occurred.

[0051] In this embodiment, the frankincense oil that has undergone stirring and dispersion treatment needs to be matured to allow the silane coupling agent to fully react with the frankincense oil and form a stable molecular structure. Therefore, the prepared frankincense oil is allowed to stand for 10–12 hours at room temperature for maturation.

[0052] Through the above processing steps, the modified frankincense oil gains chemical bonding ability and enhanced mechanical properties, enabling it to form a stable bonding layer with the surface of the raw material, thus ensuring the adhesion of pigments and the stability of the pattern in subsequent steps.

[0053] For step S3, in this embodiment, to achieve effective bonding between the frankincense oil and the surface of the raw embryo, and to provide a stable foundation for subsequent pigment adhesion, a bonding layer is formed by uniformly coating modified frankincense oil. This bonding layer can firmly bond to the surface of the raw embryo through chemical and physical interactions, while also exhibiting good adhesion properties for pigments.

[0054] In this embodiment, the modified frankincense oil used is the frankincense oil prepared in step S2 above, which has been chemically modified by adding silane coupling agents and nanoparticles, resulting in high adhesion and enhanced interfacial bonding properties. The frankincense oil must be thoroughly mixed before use to ensure the uniform distribution of nanoparticles and active ingredients.

[0055] In this embodiment, modified frankincense oil is coated onto the virgin embryo that has undergone surface hydroxylation treatment. The coating method can be manual application using a soft brush or spraying equipment to ensure that the frankincense oil evenly covers the surface of the embryo. To achieve optimal adhesion, the coating thickness is controlled between 50 and 100 μm, providing sufficient adhesion while preventing delamination or flow during firing due to excessive coating thickness.

[0056] In this embodiment, care must be taken to avoid generating bubbles or causing coating breakage during the coating process. If localized unevenness occurs, the coating can be repeated until the surface is smooth and free of defects.

[0057] After coating, the frankincense oil is dried in this embodiment. To remove volatile components from the frankincense oil and allow it to partially solidify, the coated raw material is placed in an environment of 50–60°C for low-temperature drying for 10–15 minutes. During the drying process, excessive flow of the frankincense oil or deactivation of its chemical components due to high temperatures must be avoided.

[0058] After the drying process is completed, in this embodiment, the unglazed embryo is left to stand for 1 to 2 hours to allow the silane coupling agent in the frankincense oil to fully react with the hydroxyl groups on the surface of the embryo, forming stable chemical bonds (S iOS i bonds). This reaction process is a key step in the formation of the bonding layer by the frankincense oil coating, ensuring that the bonding layer will not decompose or detach from the surface of the embryo during the high-temperature firing process.

[0059] Through the above operations, the frankincense oil bonding layer formed in this embodiment has high chemical stability and physical adhesion, providing a reliable basis for the uniform distribution and adhesion of pigments in subsequent steps.

[0060] For step S4, in this embodiment, to achieve the production of Thangka combining porcelain painting techniques, it is necessary to complete the line drawing and coloring operations on the surface of the unglazed porcelain body coated with modified frankincense oil. Through this process, the artistic expression and functional design of the pattern can be realized, while laying the foundation for the subsequent firing steps.

[0061] In this embodiment, line drawing is a crucial step in Thangka production, serving to establish the basic framework of the design and ensuring that subsequent coloring operations strictly adhere to the design requirements. In this embodiment, the pigment used is black pigment, whose main components are iron oxide or copper oxide. This pigment possesses high-temperature stability, enabling it to maintain the clarity and integrity of the lines during firing.

[0062] In this embodiment, a brush or fine needle is used as the drawing tool when creating the line art to achieve precise control of the lines and express the complexity of the pattern. During the drawing process, it should be ensured that the black pigment is evenly distributed on the surface of the frankincense oil bonding layer to avoid unclear lines or uneven thickness due to pigment aggregation. To ensure the quality of the drawing, it is recommended to carry out the work in a well-ventilated indoor environment to reduce the influence of external factors on pigment adhesion.

[0063] In this embodiment, after the line drawing is completed, coloring is required. The pigments used are pastel pigments or new color pigments, chosen for their excellent color expression and high-temperature firing stability. The coloring process can achieve transitional effects for complex patterns through gradient application techniques. Especially in the color layering designs common in Thangka art, gradient coloring can showcase the three-dimensionality and depth of the pattern.

[0064] In this embodiment, the coloring process should follow the pre-drawn outline to ensure that the applied paint completely covers the target area, while avoiding going beyond the boundaries or covering the outline. The paint can be applied in multiple layers, with each layer applied only after the previous layer has dried, to ensure uniformity and depth of color.

[0065] In this embodiment, special attention must be paid to the adhesion of the coating during the entire process of line drawing and coloring. Due to the presence of the frankincense oil binding layer, the pigment can form good adhesion with the surface of the unglazed body. However, during the pigment application process, excessive water or an excessively thick pigment layer should be avoided to prevent the pigment from flowing or delaminating during subsequent firing.

[0066] Through the above operations, the line drawing and colored pattern completed in this embodiment can meet the high artistic requirements of Thangka craftsmanship, while also possessing good pigment adhesion and firing stability, providing a reliable foundation for the firing process in subsequent steps.

[0067] For step S5, in this embodiment, in order to fix the completed line drawing and colored pattern to the surface of the unpainted Thangka and ensure the color stability and durability of the pattern, the unpainted Thangka needs to undergo a firing process. The firing process is a crucial step in this invention, directly affecting the physical stability and artistic expression of the finished Thangka.

[0068] In this embodiment, the firing process includes at least one initial firing and a second firing as needed. The initial firing is mainly used to fix the pattern and pigments, allowing them to form a firm bond with the surface of the raw body. The initial firing temperature is set to 800℃, and the holding time is 6–8 hours. Within this temperature range, the metal oxides in the pigments chemically bond with the modified frankincense oil bonding layer, while the components of the modified frankincense oil layer solidify at high temperature, forming a stable interface bond with the surface of the raw body.

[0069] In this embodiment, the initial firing must be carried out in a firing furnace with good temperature uniformity and controllable heating and cooling rates. Before firing, the colored blanks are evenly placed in the firing furnace to avoid localized overfiring or underfiring caused by improper placement of the blanks. The heating rate needs to be controlled at 50-100℃ / hour to ensure uniform heating of the blanks and avoid surface cracks or coating peeling caused by excessively rapid heating.

[0070] In this embodiment, a second firing can be performed as needed after the initial firing. The main purpose of the second firing is to adjust the details and color layers of the pattern, further enhancing its color saturation and expressiveness. The temperature for the second firing is set to 800–850°C, and the holding time is 4–6 hours. During the second firing process, the color components in the pigment layer and the frankincense oil bonding layer are further solidified, while any residual moisture or volatile components that may remain under high temperature are completely eliminated, thereby improving the durability and stability of the pattern.

[0071] In this embodiment, if a gold effect is desired to add to the pattern, gold pigment can be applied before the second firing, followed by a final low-temperature firing. The low-temperature firing temperature is controlled at 600–700°C, and the holding time is 2–3 hours. Low-temperature firing can effectively protect the color and adhesion of the gold pigment, avoiding oxidation or discoloration caused by high temperatures.

[0072] In this embodiment, after firing, the green body needs to be allowed to cool naturally to room temperature, typically for 6 to 8 hours. During the cooling process, rapid cooling should be avoided to prevent the green body from cracking due to excessive thermal stress or causing damage to the surface pattern's adhesion layer.

[0073] Through the above steps, the firing process in this embodiment can firmly fix the pigment pattern on the surface of the unglazed piece, while ensuring the color uniformity, saturation and overall stability of the pattern, providing an important guarantee for the long-term preservation of the finished Thangka.

[0074] In step S6 of this embodiment, to ensure that the finished Thangka meets the required quality standards after firing, the finished product needs to be naturally cooled and inspected after the firing process is completed. This step has a direct impact on the final performance, structural integrity, and pattern effect of the finished product.

[0075] In this embodiment, after firing, the patterned unglazed piece is removed from the kiln and placed in a well-ventilated room temperature environment for natural cooling. The cooling rate must be strictly controlled during the cooling process, typically for 6 to 8 hours. The purpose of natural cooling is to slowly release the thermal stress introduced by high-temperature firing, avoiding cracking, deformation, or peeling of the surface coating caused by rapid cooling.

[0076] In this embodiment, during the cooling process, the preform should be kept away from environments with excessive humidity or poor ventilation to prevent localized cracks or reduced adhesion of the pigment layer due to surface condensation. No artificial acceleration is required during the cooling process to ensure the overall stability of the preform.

[0077] In this embodiment, after the finished product cools to room temperature, a detailed inspection of the appearance and structure of the Thangka is required. First, the integrity of the surface pattern is visually checked to ensure that there are no peelings, bubbles, or over-firing. Simultaneously, the boundaries between the line drawing and the painted areas are checked for clarity, and the colors of the pattern are checked for uniformity.

[0078] In this embodiment, to further confirm the pattern quality and surface adhesion performance, an optical microscope can be used to magnify and observe the Thangka surface. Microscopic observation allows for the examination of the distribution of pigment particles, ensuring that no aggregation or delamination of the pigments occurred during firing. Simultaneously, the interface between the frankincense oil bonding layer and the unglazed surface can be observed to determine the quality of their bonding.

[0079] In this embodiment, after completing the visual inspection, the color durability of the finished Thangka painting also needs to be evaluated. This can be done by subjecting the finished sample to a simulated high humidity and high temperature environment to observe whether the surface pigments maintain adhesion and color stability. This test provides an important basis for the long-term preservation performance of the finished Thangka painting.

[0080] Through the above operations, this embodiment completes the cooling and inspection of the finished Thangka. Controlling the cooling process ensures the stability of the finished product's structure, while the inspection process ensures the Thangka's appearance quality, color expressiveness, and long-term durability.

[0081] In summary, this invention enhances adhesion by introducing and activating surface hydroxyl groups through surface hydroxylation treatment of the raw embryo; prepares modified frankincense oil, and utilizes silane coupling agents and nanoparticles to enhance the chemical bonding ability and physical stability of the frankincense oil; uniformly coats the modified frankincense oil onto the surface of the raw embryo to form a stable bonding layer; draws line art and paints on the bonding layer to achieve the artistic expression of Thangka patterns; fixes the patterns and enhances durability through multiple high-temperature firings; and finally obtains the finished product through natural cooling and rigorous inspection.

[0082] To better understand the present invention, the above method will be described in detail below with reference to specific embodiments.

[0083] Example 1: A method for preparing Thangka paintings using modified frankincense oil through traditional processes

[0084] In this embodiment, an unglazed ceramic blank with a thickness of 3-6 mm was selected as the substrate. First, the blank underwent surface hydroxylation treatment by immersing it in a 0.5% nitric acid solution for 3 minutes to remove surface impurities and introduce hydroxyl groups. After acid washing, it was rinsed with distilled water until neutral and then subjected to high-temperature treatment at 400°C for 2 hours to activate the hydroxyl groups.

[0085] Next, modified frankincense oil was prepared by adding 3% 3-aminopropyltriethoxysilane (KH550) to natural frankincense oil and stirring at 300 rpm for 15 minutes using a magnetic stirrer to ensure uniform dispersion of the silane. Then, 0.5% nano-silica particles (30 nm in diameter) were added and dispersed at 2000 rpm for 10 minutes using a high-speed disperser. The modified frankincense oil was then allowed to stand for 12 hours to complete the maturation process.

[0086] Modified frankincense oil was evenly coated onto the surface of the unglazed porcelain blank to a thickness of 80 μm and dried at 50°C for 10 minutes, followed by standing for 1 hour to complete the chemical bonding of silane and hydroxyl groups. After coating, traditional Thangka patterns were drawn on the frankincense oil-bonded layer. The line drawing was performed using iron oxide black pigment, and pastel pigments were applied on the line drawing to complete the pattern design.

[0087] Finally, the unglazed body is first fired at 800℃ and held for 6 hours to fix the pattern; then it is fired again as needed at 820℃ and held for 4 hours to enhance the color expression and stability of the pattern.

[0088] Example 2: A method for preparing Thangka paintings with optimized colors through low-temperature firing.

[0089] In this embodiment, a 4mm thick preform was selected as the substrate. First, the preform was immersed in a 1% acetic acid solution for 5 minutes to remove surface contaminants and introduce hydroxyl groups. After pickling, it was rinsed multiple times with distilled water until neutral, and then heat-treated at 450°C for 3 hours to further activate the hydroxyl groups.

[0090] To prepare the modified frankincense oil, 5% KH550 silane coupling agent was added to the frankincense oil and stirred at 500 rpm for 10 minutes. Then, 1% alumina nanoparticles (20 nm in diameter) were added, and the mixture was stirred at 2500 rpm for 5 minutes using a high-speed disperser to ensure uniform particle distribution. The modified frankincense oil was aged for 10 hours.

[0091] Modified frankincense oil was coated onto the surface of the unpainted Thangka to a thickness of 70 μm, achieving uniform distribution through spraying. After coating, it was dried at 60°C for 15 minutes and then allowed to stand for 2 hours to complete the chemical reaction. A simplified Thangka line drawing was then created on the frankincense oil-coated layer using copper oxide black pigment. Subsequently, new color pigments were applied over the line drawing, and the color transition of the pattern was achieved through multi-layered gradient application.

[0092] After the coloring is completed, the unglazed body is first fired at 780℃ and held for 8 hours. Then, gold decoration is added and fired at a low temperature of 650℃ for 3 hours to protect the color stability of the gold pigment.

[0093] Example 3: Preparation method of Thangka making optimized by high-strength pigment adhesion

[0094] In this embodiment, a 5mm thick preform was selected for processing. The preform was first soaked in a 1.5% nitric acid solution for 4 minutes to remove impurities, and then rinsed with distilled water until neutral. Subsequently, it was subjected to high-temperature treatment at 420°C for 2.5 hours to activate the surface hydroxyl groups and form a uniform chemical bonding interface.

[0095] In the preparation of modified frankincense oil, 4% KH550 was added to the frankincense oil and stirred at 400 rpm for 15 minutes. Subsequently, 0.8% nano-silica particles (particle size 10 nm) were added and dispersed at 3000 rpm for 10 minutes. The frankincense oil was allowed to stand and mature for 11 hours to ensure that the silane was fully combined with the frankincense oil molecules.

[0096] Modified frankincense oil was evenly applied to the surface of the unpainted canvas using a soft brush, with a coating thickness of 100 μm. The canvas was dried at 55°C for 12 minutes. After drying, it was allowed to stand for 1.5 hours to allow for chemical bonding. Intricate Thangka line drawings were then created on the coating using a fine needle, employing iron oxide black pigment. Pastel pigments were then layered onto the line drawings, ensuring each layer was completely dry before applying the next to guarantee uniform color.

[0097] After the coloring is completed, the pattern is first fired at 820℃ for 7 hours to fix it. A second firing at 850℃ for 5 hours is then performed as needed to further enhance the color saturation and adhesion of the pattern.

[0098] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method of preparing Thangka by combining the ceramic painting process, characterized by, The method comprises the following steps: 1) surface hydroxylation treatment of the blank, including soaking the blank in a dilute acid solution to remove surface impurities and introduce hydroxyl groups, and then high-temperature heat treatment to activate the hydroxyl groups; 2) preparation of modified frankincense oil, including adding a silane coupling agent and nanoparticles to the frankincense oil, uniformly dispersing and then standing for maturation; 3) uniformly coating the modified frankincense oil on the surface of the blank treated by hydroxylation, and drying and standing to form a stable bonding layer; 4) drawing a line drawing on the surface of the blank coated with frankincense oil, and applying pigments to complete the pattern design; 5) firing the pattern, at least once primary firing and optional secondary firing, to fix the pattern and color; 6) natural cooling after firing to obtain the finished Thangka.

2. A method of preparing Thangka as claimed in claim 1, wherein, The dilute acid solution in the hydroxylation treatment is a 0.5-1.5% nitric acid solution or acetic acid solution, and the soaking time is 3-5 minutes; the high-temperature heat treatment temperature is 400-450℃, and the duration is 2-3 hours.

3. A method of preparing Thangka as claimed in claim 1, wherein, The silane coupling agent added to the frankincense oil is 3-5% 3-aminopropyl triethoxysilane, and the nanoparticles are 0.5-1% silicon dioxide or aluminum oxide, with a particle size of 10-50 nm.

4. A method of preparing Thangka as claimed in claim 1, wherein, The coating thickness of the modified frankincense oil is 50-100μm, and the low-temperature drying after coating is carried out at 50-60℃ for 10-15 minutes.

5. A method of preparing Thangka as claimed in claim 1, wherein, The line drawing is drawn using black pigment, and the black pigment is iron oxide or copper oxide, which is uniformly coated on the surface of the frankincense oil bonding layer.

6. A method of preparing Thangka as claimed in claim 1, wherein, The primary firing temperature is 800℃, and the duration is 6-8 hours, and the secondary firing temperature is 800-850℃, and the duration is 4-6 hours.

7. A method of preparing Thangka as claimed in claim 1, wherein, In the method, if a gold-colored part is needed in the pattern, a gold-colored pigment is applied, and a final low-temperature firing is carried out at a temperature of 600-700℃ for a duration of 2-3 hours.

8. A method of preparing Thangka as claimed in claim 1, wherein, The cooling method is natural cooling to room temperature, and the cooling time is 6-8 hours.

9. Thangka incorporating the technique of ceramic painting, characterized in that, The Thangka combined with the porcelain drawing process is prepared by the method of any one of claims 1-8.

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