Anti-cracking stable burning process for large-size solid purple sand pottery printing

Abstract

The invention discloses a large-size solid purple sand pottery printing anti-cracking stable sintering process, which comprises the steps of mud formula optimization, stepped drying pretreatment, three-stage precise heating and gradient cooling, and the mud formula comprises the following necessary components by weight: 55-65 parts of purple mud, 20-25 parts of red mud, 8-12 parts of segment mud, 4-6 parts of natural quartz sand (200 mesh), and 28-32 parts of drinking water. According to the anti-cracking stable burning process for the large-size solid purple sand pottery printing, by means of the natural characteristics and the optimized formula of the Karamay purple sand raw ore, the forming stability, the hardness, the abrasion resistance, the artistic effect, the safety and the durability are all stable and reliable, and the performance is excellent. The solid structure of the Karamay purple sand raw ore ensures stress uniformity and placement stability during affixing, the double-pore structure of the Karamay purple sand raw ore improves the slurry wrapping rate and the seal impression definition, the high-temperature sintering process enables heavy metal ions to be solidified, and the safety of multi-scene use is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of Zisha pottery seal firing technology, specifically a crack-resistant and stable firing process for large-size solid Zisha pottery seals. Background Technology

[0002] As a fusion of traditional Chinese seal carving art and ceramic craftsmanship, Zisha (purple clay) seals possess both cultural value and practical function, and are widely used in calligraphy and painting creation, cultural collection, and customized gifts. Zisha clay, rich in silica, alumina, and iron oxide, exhibits excellent plasticity, breathability, and stability. After firing, it has a dense texture and a warm, mellow tone, making it a preferred material for seal making. With the booming development of the cultural and creative industries, market demand for Zisha seals is gradually extending towards "larger sizes, personalization, and artistry." The demand for large-format cultural and creative ornaments and public space art decorations is increasing, driving the industry to explore the research and development and production of larger-sized products.

[0003] Meanwhile, the industrialization of regionally distinctive resources has become an important direction for the development of the cultural industry. Taking the colorful purple clay resources of Karamay as an example, its unique mineral composition and color texture provide a natural advantage for the creation of purple clay seals. However, how to transform regional resources into large-scale, high-value-added cultural and creative products has become a key issue for the development of the local industry. As an important carrier of regional culture, breakthroughs in the stable production process of large-sized solid purple clay seals are of great significance for the development of regional cultural resources and the innovation and upgrading of traditional crafts. Traditional purple clay seals are mainly small in size (≤10cm), and their firing process has formed a mature system. However, when the product size is increased to ≥20cm and is solid, traditional processes are difficult to adapt and face many technical bottlenecks. 1. Challenges brought by the structural characteristics of the green body: Large solid green bodies are thick, making it difficult for internal moisture to drain naturally, and the heat conduction rate is slow, resulting in a significant moisture gradient and temperature gradient between the inside and the surface of the green body during the firing process. 2. Problem of internal stress accumulation and release: In traditional processes, the steam pressure generated by the rapid evaporation of moisture and the volume changes caused by thermal expansion and contraction will form strong internal stress in large solid billets, which is difficult to release through conventional processes, eventually leading to the billet burning and cracking. 3. Insufficient adaptability of existing processes: The drying methods, heating curves, and cooling processes of traditional firing processes are all designed for small-sized blanks and lack targeted optimization for large-sized solid structures, resulting in extremely low yield of large-sized products (generally less than 30% in the industry). 4. Mismatch between material properties and large-size requirements: The shrinkage ratio and density of virgin Zisha clay are prone to uneven shrinkage during the firing of large solid blanks, which further aggravates the risk of cracking and deformation.

[0004] Furthermore, the industry has long lacked mature firing standards specifically for solid Zisha pottery seals ≥20cm in size. Related technical research has largely focused on small-sized products or hollow large-sized products. The crack-prevention and stable firing technology for solid large-sized products has become a recognized technical pain point in the industry, severely limiting the expansion of application scenarios and large-scale production of Zisha pottery seals. Therefore, those skilled in the art have provided a crack-prevention and stable firing process for large-sized solid Zisha pottery seals to solve the problems mentioned in the background. Summary of the Invention

[0005] The purpose of this invention is to provide a crack-resistant and stable firing process for large-size solid purple clay ceramic seals, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A crack-resistant and stable firing process for large-size solid purple clay seals includes clay formula optimization, stepped drying pretreatment, three-stage precise heating and gradient cooling steps. The clay formula includes the following essential components in parts by weight: 55-65 parts purple clay (raw ore), 20-25 parts red clay (raw ore), 8-12 parts duan clay (raw ore), 4-6 parts natural quartz sand (200 mesh), and 28-32 parts drinking water.

[0007] As a further embodiment of the present invention, the mud material formula further includes one or more of the following optional components in parts by weight: 0.6-1.2 parts of pyrolusite powder (300 mesh), 1.2-2.0 parts of chlorite powder, and 0.5-1.0 parts of feldspar powder.

[0008] As a further aspect of the present invention, the stepped drying pretreatment process specifically involves drying at 40°C for 12 hours and then drying at 60°C for 24 hours.

[0009] As a further aspect of the present invention: the three-stage precise heating curve is as follows: the temperature is increased at a rate of 2℃ / min in the 0-300℃ stage, at a rate of 4℃ / min in the 300-500℃ stage, and at a rate of 3℃ / min in the 500-800℃ stage, and then held at 800℃ for 2 hours.

[0010] As a further aspect of the present invention, the gradient cooling technology specifically involves: controlling the cooling rate at a rate of 2°C / min for the stage above 500°C, and allowing natural cooling for the stage below 500°C.

[0011] As a further aspect of the present invention, the clay formula is characterized by the addition of 3% of 500-mesh special mineral material, which is used to adjust the shrinkage ratio and density of large-sized blanks.

[0012] As a further aspect of the present invention: the size of the large-sized solid purple clay pottery seal is ≥20cm, and the preferred size is 20cm×20cm×8cm.

[0013] As a further aspect of the present invention: the dimensional deviation of the large-sized solid purple clay pottery seal after firing is ≤0.3%, the surface hardness reaches 7.6H or above, and the mass loss rate is controlled within 10.5%.

[0014] As a further embodiment of the present invention: the large-size solid purple clay ceramic seal after firing has a compressive strength ≥85MPa, a water absorption rate ≤2.5%, and a lead and cadmium leaching amount ≤0.01mg / L.

[0015] The large-size solid purple clay pottery seal prepared by the above process is characterized by its application in calligraphy and seal engraving art creation, cultural display and collection, intangible cultural heritage inheritance and teaching, regional cultural gift customization and public cultural space decoration.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1. The large-size solid purple clay pottery seal anti-cracking and stable firing process of this invention relies on the natural characteristics of Karamay purple clay ore and an optimized formula. It is stable and reliable in terms of molding stability, hardness and wear resistance, artistic effect, safety and durability, and exhibits excellent performance. The solid structure ensures uniform force and placement stability during stamping. The double-pore structure of Karamay purple clay ore improves the patina formation rate and the clarity of the imprint. The high-temperature sintering process solidifies heavy metal ions, ensuring safety for use in multiple scenarios. It fully meets the functional requirements of core applications such as artistic creation, cultural display, intangible cultural heritage preservation, customized gifts, and public decoration.

[0017] 1. It can achieve stable firing of solid purple clay seals ≥20cm (e.g., 20cm×20cm×8cm), with no cracks, no shattering, and no obvious deformation in the finished product, and a size deviation of ≤0.3%, greatly improving the yield of large-size products; after firing, the seal has a dense texture, a surface hardness of 7.6H or higher, a mass loss rate controlled within 10.5%, a compressive strength ≥85MPa, and a water absorption rate ≤2.5%, meeting the practicality and durability requirements of seals.

[0018] 3. Achieve a stable supply of large-size solid purple clay pottery seals, and promote their extension from traditional small seals to large cultural and creative ornaments, art decorations and other diverse scenarios, thus enriching product forms. Detailed Implementation

[0019] In this embodiment of the invention, a clay formula for a large-size solid purple clay seal with anti-cracking and stable firing process is provided. Essential components: Purple clay (raw ore) 55-65 parts, providing basic density and plasticity, naturally rich in kaolin and beneficial trace elements such as iron and zinc, ensuring the stability of solid structure molding; Red clay (raw ore) 20-25 parts, enhancing color saturation (presenting a natural vermilion texture), strengthening sintering bonding, and meeting the density requirements of solid large-size structures; Duan clay (raw ore) 8-12 parts, optimizing the fineness of the body, adjusting the air permeability of the solid structure, and avoiding internal stress concentration cracking during drying and sintering; Natural quartz sand (200 mesh) 4-6 parts, reducing sintering shrinkage (strengthening the resistance to deformation for solid large-size characteristics), improving structural rigidity, and preventing overall warping; Drinking water 28-32 parts, activating the natural plasticity of Karamay purple clay, ensuring uniformity of clay preparation and aging effect, and meeting the needs of solid molding.

[0020] Optional ingredients: 0.6-1.2 parts of pyrolusite powder (300 mesh), to deepen the color and layering, giving the purple clay a natural bluish-green luster and enhancing artistic expression; 1.2-2.0 parts of chlorite powder, to improve the oiliness of the clay body and accelerate the formation of patina (suitable for the breathability of Karamay purple clay), optimizing the feel and appearance; 0.5-1.0 parts of feldspar powder, to broaden the firing temperature range, enhance the mechanical strength of the solid structure, and reduce the risk of cracking during large-size sintering.

[0021] Adding 3% of 500-mesh special mineral material to the clay is specifically designed to adjust the shrinkage ratio and density of large-sized blanks, reducing the risk of uneven shrinkage during firing.

[0022] The purple clay, duanni clay, and red clay used in this application are all sourced from raw mineral materials from the Karamay region of Xinjiang.

[0023] The preparation method is as follows: The first step is a stepped drying pretreatment process. To address the problem of difficult moisture removal from large-sized solid blanks, a stepped drying scheme of "drying at 40℃ for 12 hours and then at 60℃ for 24 hours" is adopted. This low-temperature slow drying thoroughly removes deep moisture from the blank, preventing rapid evaporation of moisture during firing from generating steam pressure that could cause cracking.

[0024] The second step involves a three-stage precise heating curve: slow dehumidification at 2℃ / min from 0-300℃ (to avoid sudden evaporation of moisture), gradual oxidation at 4℃ / min from 300-500℃ (to balance the internal and external temperatures of the billet), and slow heating at 3℃ / min from 500-800℃ (to reduce deformation and stress). Combined with the parameter of holding at 800℃ for 2 hours, internal stress is gradually released.

[0025] The third step is gradient cooling technology: adopting a gradient scheme of "controlled cooling at 2℃ / min above 500℃ and natural cooling below 500℃" to avoid secondary cracking caused by excessive temperature difference between the surface and the interior of large-sized blanks due to excessive cooling.

[0026] Example 1 Clay formula (parts by weight): 60 parts purple clay (raw ore), 22 parts red clay (raw ore), 10 parts duan clay (raw ore), 5 parts natural quartz sand (200 mesh), 30 parts drinking water, and 0.8 parts soft manganese ore powder (300 mesh).

[0027] Preparation steps: Weigh out the raw materials according to the above formula, crush the purple clay, red clay, and duan clay to 200 mesh, mix them evenly with natural quartz sand and soft manganese ore powder, add drinking water, and knead the clay three times using a vacuum clay kneading machine, with each kneading time being 15 minutes. After kneading, seal and age the clay for 7 days.

[0028] The aged clay was hand-shaped into solid blanks measuring 20cm×20cm×8cm. After the surface was trimmed, the blanks were placed in a drying oven and dried using a stepped drying method: drying at 40℃ for 12 hours, and then increasing the temperature to 60℃ for 24 hours.

[0029] The dried billet is placed in an electric kiln and subjected to a three-stage precise heating curve: heating from 0-300℃ at a rate of 2℃ / min, heating from 300-500℃ at a rate of 4℃ / min, heating from 500-800℃ at a rate of 3℃ / min, and holding at 800℃ for 2 hours.

[0030] After the heat preservation is completed, a gradient cooling technology is used: the temperature is controlled at a rate of 2℃ / min above 500℃, and after it drops to 500℃, it is naturally cooled to room temperature. The finished product is a large-sized solid purple clay seal.

[0031] Performance testing: The finished product has a dimensional deviation of 0.2%, a surface hardness of 7.8H, a mass loss rate of 9.8%, a compressive strength of 88MPa, a water absorption rate of 2.2%, a lead and cadmium leaching rate of 0.008mg / L, no cracking or deformation, clear printing, and a warm and lustrous color.

[0032] Example 2 Clay formula (parts by weight): 55 parts purple clay (raw ore), 25 parts red clay (raw ore), 12 parts duan clay (raw ore), 4 parts natural quartz sand (200 mesh), 28 parts drinking water, 1.5 parts green clay stone powder, and 0.7 parts feldspar powder.

[0033] Preparation steps: Weigh the raw materials according to the formula, crush the purple clay ore to 200 mesh, mix it evenly with natural quartz sand, chlorite powder and feldspar powder, add drinking water, vacuum knead the clay 4 times, 12 minutes each time, and age it for 10 days.

[0034] The blank is shaped into a solid body of 25cm×25cm×10cm, and after trimming, it is dried in stages: 40℃ for 12 hours and 60℃ for 24 hours.

[0035] Place the item in the electric kiln and perform a three-stage heating process: 0-300℃ 2℃ / min, 300-500℃ 4℃ / min, 500-800℃ 3℃ / min, and hold at 800℃ for 2 hours.

[0036] Gradient cooling: 2℃ / min controlled cooling above 500℃, and natural cooling to room temperature below 500℃.

[0037] Performance testing: The finished product has a dimensional deviation of 0.3%, a surface hardness of 7.6H, a mass loss rate of 10.2%, a compressive strength of 86MPa, a water absorption rate of 2.4%, a lead and cadmium leaching rate of 0.009mg / L, no cracking or burning, a dense texture, and a fast patina formation rate.

[0038] Example 3 Clay formula (parts by weight): 65 parts purple clay (raw ore), 20 parts red clay (raw ore), 8 parts duan clay (raw ore), 6 parts natural quartz sand (200 mesh), and 32 parts drinking water.

[0039] Preparation steps: Weigh the raw materials, crush the purple clay ore to 200 mesh, mix with natural quartz sand, add drinking water, vacuum knead the clay 3 times, 18 minutes each time, and let it age for 5 days.

[0040] Shaped into a solid blank measuring 22cm×22cm×9cm, and dried in stages: 40℃ for 12 hours + 60℃ for 24 hours.

[0041] Electric kiln firing: three-stage heating curve, 800℃ for 2 hours.

[0042] Gradual cooling to room temperature.

[0043] Performance testing: The finished product has a dimensional deviation of 0.25%, a surface hardness of 7.7H, a mass loss rate of 10.0%, a compressive strength of 87MPa, a water absorption rate of 2.3%, a lead and cadmium leaching rate of 0.007mg / L, stable molding, no deformation or cracking, and meets the needs of artistic creation and display.

[0044] Applications of the invention of a crack-resistant and fire-stabilizing process for large-size solid purple clay seals (≥20cm) (1) Calligraphy and seal carving art creation: As a large solid seal with a size of ≥20cm, it is suitable for calligraphy, painting, seal carving and other art creations. It is used for signing and stamping large works on Xuan paper, silk, calligraphy and painting mounting and other media. The seal text is clear and heavy, and the artistic recognition is high.

[0045] (2) Cultural Furnishings and Collections: Relying on the unique texture and solid structure of Karamay purple clay ore, it can be placed in study rooms, exhibition halls, art galleries and other spaces as a high-end cultural furnishing, which has both decorative and collection value, and becomes a carrier of regional cultural symbols.

[0046] (3) Intangible cultural heritage inheritance and teaching: It is used for the teaching of intangible cultural heritage such as Zisha pottery and seal carving, and as a practical teaching tool to help learners master the forming, carving and firing process of large-size solid pottery seals; at the same time, as an intangible cultural heritage display exhibit, it helps to spread the culture of Karamay Zisha.

[0047] (4) Customized regional cultural gifts: Customized exclusive gifts with regional logos, commemorative texts and cultural patterns for government departments, cultural institutions, enterprises and collectors, to be used in government exchanges, cultural visits, festivals and other occasions to convey the regional cultural characteristics of Karamay.

[0048] (5) Decoration of public cultural spaces: As decorative art pieces for public spaces such as urban cultural landmarks, cultural centers, museums, and libraries, large-scale thematic ceramic seals (such as those engraved with urban spirit, cultural sayings, and historical allusions) can be customized to enrich the regional connotation of public cultural scenes.

[0049] The effects of its use and the principles by which it achieves its function (1) Core Use Effects ① Artistic Creation Effect: The imprint is clear and full, and the seal penetrates the back of the paper. The solid structure ensures even pressure when pressed, without shaking or deformation. It is suitable for the imprinting needs of large-scale calligraphy and painting works. The imprint is long-lasting and does not smudge. The color is warm and rich, and the patina forms 35% faster than ordinary ceramic seals. The artistic quality gradually improves with the use of time.

[0050] ② Display and collection effect: The solid structure has a stable and heavy texture, and it is stable and will not tip over when placed. The large size of ≥20cm has both visual impact and scarcity. The natural texture of Karamay purple clay is unique, and each piece is a "natural one-of-a-kind". Its collection value and regional cultural attributes are prominent, and there is no risk of oxidation and deterioration when stored for a long time.

[0051] ③ Teaching and inheritance effect: The solid body has a stable structure, which is convenient for repeated demonstration of forming and carving techniques in teaching and is not easily damaged; the material is safe and odorless, and the lead and cadmium leaching amount is ≤0.01mg / L, which meets the safety standards for teaching tools; it intuitively presents the characteristics of Karamay purple clay and the key points of large-size ceramic seal making, helping learners to quickly master the core skills.

[0052] ④ Gift Usage Effect: Highly customized, it can accurately present regional symbols and commemorative information, combining practicality and cultural connotation; the solid texture and original mineral texture highlight high-end quality, suitable for multiple scenarios such as government affairs, culture, and business, becoming a "mobile business card" for regional cultural exchanges.

[0053] ⑤ Public decoration effect: The large-size solid structure is suitable for the display needs of public spaces. It is wear-resistant and weather-resistant (compressive strength ≥85MPa, water absorption ≤2.5%). It is not easy to crack or deform when placed indoors or outdoors for a long time. Thematic patterns and text can convey the cultural spirit of the city and enhance the cultural atmosphere and regional recognition of public spaces.

[0054] (2) Functional Implementation Principle ① Artistic effect principle: After being sintered at high temperature, the raw purple clay of Karamay forms a dense and breathable double-pore structure, which can ensure that the seal surface is flat and hard (not easy to wear after the seal is carved), and can also make the ink adhere evenly and quickly penetrate the carrier when stamping, ensuring that the seal is clear and lasting; the solid structure has no hollow resonance, and the force is evenly transmitted when pressing, avoiding uneven seal depth.

[0055] ② Stable and durable principle: Quartz sand (4-6 parts) in the formula forms a "skeleton-filler" structure with the raw ore particles of Karamay purple clay. The shrinkage rate during sintering is controlled at 8.5%-10%, which is much lower than that of ordinary ceramic seals (13%-16%), effectively inhibiting the deformation and cracking of large solid blanks. After high-temperature sintering, the minerals undergo mullite formation to form a dense mineral lattice, which improves mechanical strength and corrosion resistance, ensuring the stability of long-term use and collection.

[0056] ③ Cultural Carrier Principle: Relying on the unique regional mineral resources of Karamay Zisha, regional cultural elements (such as city logos, petroleum culture, and Gobi scenery) are integrated into the ceramic seal through carving techniques, making the product a concrete carrier of regional culture; the solid structure and the natural texture of the raw ore enhance the scarcity and recognizability of the cultural product, and help the dissemination and inheritance of regional culture.

[0057] ④ Safety and environmental protection principle: The raw materials are all natural minerals (Karamay purple clay ore, quartz sand, etc.), without artificial synthetic binders or harmful additives; during the high-temperature sintering process, heavy metal ions are solidified in the mineral lattice, with extremely low leaching, which meets the GB4806.4-2016 food contact safety standard and is suitable for use in teaching, decoration, gifts and other scenarios.

[0058] 5. Experimental evidence of crack prevention and stable firing process for large-size solid purple clay pottery seals (≥20cm) (1) Experimental objective This study verifies the advantages of a large-sized solid Karamay purple clay seal (size: 20cm×20cm×8cm, solid structure) in terms of core performance such as molding stability, mechanical strength, artistic effect, safety, and durability, providing scientific data support for the invention's purpose and functional principle.

[0059] (2) Experimental methods ① Molding stability test (for solid large-size parts requiring resistance to deformation) Record the cracking rate of three groups of samples during drying (natural drying + oven drying) and sintering; measure the length, width and height dimensions before and after sintering with vernier calipers and calculate the shrinkage rate; measure the surface flatness of the samples after sintering and record the deformation.

[0060] ② Hardness and abrasion resistance test Three test points were selected for each sample (one at the center and two at the edges, evenly distributed). A Rockwell hardness tester was used to press vertically on the test points, and the hardness value of each point was recorded. The average value of the three points was taken as the final hardness of the sample. After the test, the test points were observed for indentations or cracks, and the surface condition was recorded. The surface abrasion resistance of the sample was tested (500g load, 500 rub cycles), and the amount of wear was recorded.

[0061] ③ Experiment on artistic effects (clarity of the printed text and patina effect) The three groups of samples were stamped 50 times on Xuan paper and silk respectively. The neatness of the edges of the stamped text was observed with a magnifying glass, and the clarity rate was recorded (clarity rate = number of clear imprints / total number of stamps × 100%). The samples were stamped 20 times per week, and the surface gloss was measured with a colorimeter at 1 month, 3 months and 6 months to observe the uniformity of the patina.

[0062] (3) Experimental conclusions This invention relates to a large-size solid purple clay seal (≥20cm) with a crack-resistant and stable firing process. Utilizing the natural characteristics of Karamay purple clay ore and an optimized formula, it exhibits stable and reliable performance in terms of forming stability, hardness and wear resistance, artistic effect, safety, and durability. Its solid structure ensures uniform force distribution and placement stability during stamping. The dual-pore structure of Karamay purple clay ore enhances the patina formation rate and the clarity of the imprint. The high-temperature sintering process solidifies heavy metal ions, ensuring safety for use in various scenarios. It fully meets the functional requirements of core applications such as artistic creation, cultural display, intangible cultural heritage preservation, customized gifts, and public decoration.

[0063] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A crack-resistant and stable firing process for large-size solid purple clay pottery seals, characterized in that, The process includes clay formulation optimization, stepped drying pretreatment, three-stage precise heating and gradient cooling steps. The clay formulation includes the following essential components by weight: 55-65 parts purple clay, 20-25 parts red clay, 8-12 parts duan clay, 4-6 parts 200-mesh natural quartz sand, and 28-32 parts drinking water.

2. The anti-cracking and stable firing process for large-size solid purple clay pottery seals according to claim 1, characterized in that, The mud material formula also includes one or more of the following optional components in parts by weight: 0.6-1.2 parts of 300-mesh pyrolusite powder, 1.2-2.0 parts of chlorite powder, and 0.5-1.0 parts of feldspar powder.

3. The anti-cracking and stable firing process for large-size solid purple clay pottery seals according to claim 1, characterized in that, The step-by-step drying pretreatment process is as follows: first, dry at 40°C for 12 hours, then dry at 60°C for 24 hours.

4. The anti-cracking and stable firing process for large-size solid purple clay pottery seals according to claim 1, characterized in that, The three-stage precise heating curve is as follows: the temperature rises at a rate of 2℃ / min in the 0-300℃ stage, at a rate of 4℃ / min in the 300-500℃ stage, and at a rate of 3℃ / min in the 500-800℃ stage, and is held at 800℃ for 2 hours.

5. The anti-cracking and stable firing process for large-size solid purple clay pottery seals according to claim 1, characterized in that, The gradient cooling technology specifically involves controlling the cooling rate at 2℃ / min for the stage above 500℃, and allowing natural cooling for the stage below 500℃.

6. The anti-cracking and stable firing process for large-size solid purple clay pottery seals according to claim 1, characterized in that, The clay formula also contains 3% of 500-mesh special mineral material, which is used to adjust the shrinkage ratio and density of large-sized blanks.

7. The anti-cracking and stable firing process for large-size solid purple clay pottery seals according to claim 1, characterized in that, The purple clay, red clay, and duanni clay mentioned are all raw ores.

8. The anti-cracking and stable firing process for large-size solid purple clay pottery seals according to claim 1, characterized in that, After firing, the dimensional deviation of large-sized solid purple clay pottery seals is ≤0.3%, the surface hardness reaches 7.6H or above, and the mass loss rate is controlled within 10.5%.

9. The anti-cracking and stable firing process for large-size solid purple clay pottery seals according to claim 1, characterized in that, After firing, the large-sized solid purple clay seal has a compressive strength ≥85MPa, a water absorption rate ≤2.5%, and a lead and cadmium leaching amount ≤0.01mg / L.

10. A large-size solid purple clay pottery seal prepared by the process according to any one of claims 1-9, characterized in that, It can be applied to calligraphy and seal engraving art creation, cultural display and collection, intangible cultural heritage inheritance and teaching, regional cultural gift customization and public cultural space decoration.