A silver oil-drop glaze formula based on vanadium-titanium magnetite and a firing method thereof

Abstract

This invention discloses a silver oil-drop glaze formula and firing method based on vanadium-titanium magnetite, relating to the field of inorganic materials technology. The invention uses an iron-cobalt-chromium composite system as a colorant, introducing iron, chromium, and cobalt elements into the glaze in the form of multi-element composite crystals. Under the synergistic effect of phase separation and crystallization, it forms silver oil-drop patterns with uniform distribution and strong metallic texture. Under this composite system, the resulting silver oil-drop glaze has a glossy black surface, with bright, regular, and full-sized oil drop crystals, a bright metallic luster, and a delicate, three-dimensional texture, possessing both an antique and refined quality. Moreover, the formation conditions for the silver oil-drop patterns are more relaxed and controllable, significantly improving the product's quality stability and pass rate, making it suitable for the industrial production of silver oil-drop glaze.

Description

Technical Field

[0001] This invention relates to the field of inorganic materials technology, mainly to the field of ceramic glaze materials technology, and specifically to a silver oil-drop glaze formulation based on vanadium-titanium magnetite and its firing method. Background Technology

[0002] Silver oil-spot glaze is a type of black-glazed porcelain, belonging to the category of crystalline glazes. In the Song Dynasty, oil-spot teacups were highly favored for their suitability for tea competitions. The "Juntai Guan Zuoyou Zhang" listed oil-spot Jian ware as the "second most precious treasure," demonstrating its rarity. Its glaze surface is covered with round dots of varying sizes, ranging from the size of a pinhead to several millimeters in diameter, resembling oil droplets scattered against a black glaze background, like stars in a dark night sky.

[0003] Currently, the traditional firing technique of silver oil-spot glaze in China is represented by Jian ware from the Song Dynasty in Jianyang, Fujian. Huai'ren oil-spot glaze is a typical representative of northern silver oil-spot glaze, characterized by its black, lustrous glaze, silvery-gray metallic luster in the oil-spot crystals, round and full particles, even distribution, and a bright, regular glaze surface with a strong three-dimensional effect. Its shapes are simple and bold, with a fine glaze, possessing both a dignified and luxurious quality. Current technical analysis reveals that the chemical composition of silver oil-spot glaze generally falls within the following range: 4-8 parts ferric oxide, 6-9 parts calcium oxide, more than 2 parts magnesium oxide, no more than 20 parts aluminum oxide, and small amounts of phosphorus pentoxide. Based on the compositional analysis of silver oil-spot glaze, various existing firing methods and formulas have been used to prepare silver oil-spot glaze products. Current imitation firing techniques for silver oil-spot glaze typically use electric kilns or gas kilns instead of dragon kilns, simulating the firing atmosphere through artificial temperature control, thus achieving relatively good industrial production of silver oil-spot glaze.

[0004] However, due to the unreasonable design of existing silver oil-spot glaze formulas and firing methods, the existing silver oil-spot glaze firing process still has the following problems: limited raw material sources, high firing costs, easy environmental pollution, low product qualification rate, and poor quality stability, which seriously restricts the development and application of silver oil-spot glaze related technologies and products. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of low product qualification rate, poor quality stability and easy environmental pollution caused by the existing silver oil-drop glaze firing process. It proposes a silver oil-drop glaze formula and firing method based on vanadium-titanium magnetite.

[0006] To achieve the above objectives, the present invention provides a silver oil-drop glaze formulation based on vanadium-titanium magnetite, which is prepared from the following raw materials in parts by weight: 15-20 parts potassium feldspar, 35-45 parts sodium feldspar, 10-15 parts kaolin, 8-10 parts quartz, 6 parts calcite, 5 parts talc, 3 parts borax, 6.1 parts vanadium-titanium magnetite, 2.3-2.8 parts Cr2O3, and 2.6 parts CoCO3.

[0007] This invention discloses a silver oil-drop glaze formula based on vanadium-titanium magnetite. It employs an iron-cobalt-chromium composite system as a colorant, introducing iron, chromium, and cobalt elements into the glaze in the form of multi-element composite crystals. Through the synergistic effect of phase separation and crystallization, it forms uniformly distributed silver spots with a strong metallic texture. Under this composite system, not only is the glaze quality significantly improved (the silver oil-drop glaze has a glossy black surface, with bright, regular, and uniformly sized silver droplets, a bright metallic luster, a delicate texture, and a strong three-dimensional effect, possessing both a rustic and refined quality), but the formation conditions for the silver oil-drop patterns are also more relaxed (it can be fired in an oxidizing atmosphere; the firing temperature is lower, and the temperature control range is wider; the raw material ratio is more flexible), resulting in better controllability and significantly improved product quality stability and yield. This makes it suitable for the industrial production of silver oil-drop glaze.

[0008] To achieve the above objectives, the present invention further provides a method for firing a silver oil-spot glaze based on vanadium-titanium magnetite, comprising the following steps: (1) Pulping: Grind and sieve the raw materials and water weighed according to the formula to obtain glaze slurry; (2) Aging: The glaze slurry is left to stand and age to obtain aged glaze slurry; (3) Glazing: After stirring the aged glaze slurry evenly, glaze it on the surface of the body to obtain a glazed body; (4) Firing: The glazed body after air drying is fired in an oxidizing atmosphere and cooled to room temperature in the furnace to obtain silver oil-drop glaze.

[0009] This invention discloses a method for firing silver oil-drop glaze based on vanadium-titanium magnetite. This method not only utilizes an oxidizing atmosphere for firing, effectively improving the problems of poor product stability and environmental pollution caused by exhaust gases under a reducing atmosphere, but also lowers the maximum firing temperature, effectively reducing firing costs (energy consumption and equipment) and environmental impact, thus achieving energy conservation and environmental protection. Furthermore, it employs a rapid cooling method, significantly suppressing the coarsening of silver crystals without affecting product quality and yield. This results in a high-quality glaze with uniform silver spot distribution and a strong metallic texture, while significantly shortening the production cycle. The method for firing silver oil-drop glaze of this invention is simple, highly controllable, produces stable product quality, is environmentally friendly and energy-saving, and is suitable for large-scale production of silver oil-drop glaze.

[0010] In step (1), preferably, the mass ratio of the raw material to water is 1:0.7-0.9; the preferred material-to-water ratio results in moderate glaze viscosity, better raw material dispersion, and is more conducive to glazing.

[0011] Preferably, ball milling is used for grinding; the mass ratio of raw material to grinding balls is 1:1.8-2.2; the preferred material-to-ball ratio results in higher ball milling efficiency, more uniform raw material particle size, and better dispersibility.

[0012] Preferably, the grinding speed is 400-450 r / min and the grinding time is 10-15 min; under the preferred grinding conditions, the grinding efficiency is higher, the energy consumption is lower, and the grinding effect is better.

[0013] Preferably, after grinding, the glaze is passed through a 200-300 mesh sieve; if the glaze slurry particles are too fine, cracking is likely to occur during firing; if the particles are too large, the glaze surface is rough and the texture is uneven.

[0014] In step (2), preferably, the aging temperature is room temperature, more preferably 20-30℃; the time is 20-28h; the preferred aging conditions result in better aging effect.

[0015] In step (3), preferably, the glaze thickness is controlled to be 1.5-2.0 mm when glazing. The preferred glaze thickness results in a smoother glaze surface, which is less prone to cracking during firing and helps to improve the product qualification rate.

[0016] In step (4), preferably, the oxidizing atmosphere is air or oxygen; the resulting silver oil drop glaze has better quality.

[0017] Preferably, the firing process includes: first, heating at a rate of 4-6℃ / min to 950-970℃; then heating at a rate of 1-2℃ / min to 1110-1130℃; then heating at a rate of 3-5℃ / min to 1190-1210℃; next, heating at a rate of 0.4-0.6℃ / min to reach the maximum firing temperature of 1220-1240℃ and holding at that temperature for 25-35 minutes; finally, cooling at a rate of 3.2-3.4℃ / min to 1120-1140℃ and holding at that temperature for 30-60 minutes. This preferred firing process can effectively reduce glaze defects and improve quality stability. Without affecting product quality and yield (the glaze will not crack due to excessive cooling), it significantly inhibits the coarsening of silver crystals, thereby obtaining a high-quality glaze with uniform silver spot distribution and a strong metallic texture, thus significantly improving the product yield.

[0018] Preferably, the furnace cooling rate is 8-15℃ / min.

[0019] The beneficial effects of this invention are: 1. The silver oil-drop glaze formula of this invention uses an iron-cobalt-chromium composite system as a colorant. The glaze surface is black and lustrous, the oil drop crystals are bright and regular, the particles are full and uniform, the metallic luster is bright, the glaze is delicate and three-dimensional, and it has both an antique and exquisite texture.

[0020] 2. The silver oil-drop glaze formula of this invention uses an iron-cobalt-chromium composite system as a colorant, which allows for more relaxed formation conditions, better controllability, and significantly improved product quality stability and pass rate.

[0021] 3. The firing method of the silver oil-spot glaze of the present invention utilizes an oxidizing atmosphere for firing, which effectively improves the problems of poor stability of finished products and environmental pollution caused by exhaust gas under a reducing atmosphere.

[0022] 4. The firing method of the silver oil-spot glaze of the present invention has a lower maximum firing temperature, which effectively reduces firing costs (energy consumption and equipment) and environmental impact, and is energy-saving and environmentally friendly.

[0023] 5. The firing method of the silver oil-spot glaze of the present invention adopts a rapid cooling method, which significantly inhibits the coarsening of silver crystals without affecting product quality and yield. Thus, it can obtain a high-quality glaze with uniform silver spot distribution and strong metallic texture, while significantly shortening the production cycle.

[0024] 6. The firing method of the silver oil-spot glaze of the present invention is simple, has good controllability, produces stable product quality, is environmentally friendly and energy-saving, and is suitable for large-scale production of silver oil-spot glaze. Attached Figure Description

[0025] Figure 1 These are photographs of silver oil-spot glaze samples obtained in Examples 1-4 of this invention.

[0026] Figure 2 These are photographs of silver oil-spot glaze samples obtained by firing in Comparative Examples 1-5 of this invention.

[0027] Figure 3 The image shows the actual silver oil-spot glaze product obtained in Example 1 of this invention (where 1-3 are conical cups; 4-6 are petal cups).

[0028] Figure 4 This is the temperature curve during the firing of the silver oil-spot glaze in Embodiment 1 of the present invention. Detailed Implementation

[0029] The technical solution of the present invention will be further described in detail below with reference to the embodiments.

[0030] Table 1 shows the chemical composition (wt%) of the raw materials used in the examples and comparative examples.

[0031] Example 1

[0032] A silver oil-drop glaze based on vanadium-titanium magnetite is prepared from the following raw materials in weight percentages: 18 parts potassium feldspar, 37 parts sodium feldspar, 10 parts kaolin, 10 parts quartz, 6 parts calcite, 5 parts talc, 3 parts borax, 6.1 parts vanadium-titanium magnetite, 2.3 parts Cr2O3, and 2.6 parts CoCO3. The specific firing method is as follows: (1) Pulping: Grind the raw materials and water according to the formula (ball mill, 200 r / min, grinding time is 12 min) and sieve (250 mesh) to obtain glaze slurry; wherein, the mass ratio of raw materials to water is controlled to be 1:0.8; the mass ratio of raw materials to grinding balls is 1:2; (2) Aging: The glaze slurry is placed in a glaze cup, sealed with plastic wrap, and left to stand at 25°C for 24 hours; (3) Glazing: After stirring the aged glaze slurry evenly, glaze it on the surface of the body (glaze by dipping: first wipe the dust on the surface of the unglazed ceramic body with a damp sponge, and add water as appropriate. After the surface of the ceramic body is dry, glaze it. Each time, immerse the ceramic body in the glaze for 8-10 seconds. You can immerse it multiple times to get a glazed body (glaze layer thickness 1.8mm). (4) Firing: The air-dried glazed body is fired in an oxidizing atmosphere (air) (first, the temperature is increased to 960℃ at a rate of 5.06℃ / min; then increased to 1120℃ at a rate of 1.6℃ / min; then increased to 1200℃ at a rate of 4℃ / min; then increased to the maximum firing temperature of 1230℃ at a rate of 0.5℃ / min and held for 30 min; finally, the temperature is decreased to 1130℃ at a rate of 3.33℃ / min and held for 60 min), and then cooled in the furnace (10℃ / min) to room temperature to obtain a silver oil-spot glaze (sample as shown). Figure 1 As shown in Figure 1; the actual product is as shown. Figure 3 (As shown).

[0033] The glaze has a deep, dark blue base color and a smooth, warm surface. It is dotted with silver-gray oil-drop crystals of varying sizes, with larger crystals in the center and smaller ones at the edges, creating a natural gradient from sparse to dense and from large to small. The oil-drop crystals are round with smooth edges, forming a strong contrast with the dark base and possessing a subtle metallic sheen, resulting in a rich overall visual depth.

[0034] Example 2

[0035] A silver oil-drop glaze based on vanadium-titanium magnetite is prepared from the following raw materials in weight percentages: 18 parts potassium feldspar, 37 parts sodium feldspar, 10 parts kaolin, 8 parts quartz, 6 parts calcite, 5 parts talc, 3 parts borax, 6.1 parts vanadium-titanium magnetite, 2.8 parts Cr2O3, and 2.6 parts CoCO3. The specific firing method is as follows: (1) Pulping: Grind the raw materials and water according to the formula (ball mill, 300 r / min, grinding time is 10 min) and sieve (200 mesh) to obtain glaze slurry; wherein, the mass ratio of raw materials to water is controlled to be 1:0.7; the mass ratio of raw materials to grinding balls is 1:2.2; (2) Aging: The glaze slurry is placed in a glaze cup, sealed with plastic wrap, and left to stand at 20℃ for 28 hours; (3) Glazing: After stirring the aged glaze slurry evenly, glaze it on the surface of the body (glaze by dipping: first wipe the dust on the surface of the unglazed ceramic body with a damp sponge, and add water as appropriate. After the surface of the ceramic body is dry, glaze it. Each time, immerse the ceramic body in the glaze for 8-10 seconds. You can glaze it multiple times) to obtain a glazed body (glaze layer thickness 2mm). (4) Firing: The air-dried glazed body is fired in an oxidizing atmosphere (air) (first, the temperature is increased to 960℃ at a rate of 5.06℃ / min; then increased to 1120℃ at a rate of 1.6℃ / min; then increased to 1200℃ at a rate of 4℃ / min; then increased to the maximum firing temperature of 1230℃ at a rate of 0.5℃ / min and held for 30 min; finally, the temperature is decreased to 1130℃ at a rate of 3.33℃ / min and held for 60 min), and then cooled in the furnace (10℃ / min) to room temperature to obtain a silver oil-spot glaze (sample as shown). Figure 1 (As shown in number 2).

[0036] The glaze has a deep, rich base color. The glaze is characterized by significant variations in the size of the oil droplet crystals; the central area contains several large main crystals, while the edge area is densely covered with fine, small crystals. The oil droplet crystals are a warm, silvery-gray color, with some crystal edges exhibiting a translucent halo. The glaze surface is smooth and free of pinholes, and the crystallization effect is ideal.

[0037] Example 3

[0038] A silver oil-drop glaze based on vanadium-titanium magnetite is prepared from the following raw materials in weight percentages: 15 parts potassium feldspar, 37 parts sodium feldspar, 10 parts kaolin, 10 parts quartz, 6 parts calcite, 5 parts talc, 3 parts borax, 6.1 parts vanadium-titanium magnetite, 2.3 parts Cr2O3, and 2.6 parts CoCO3. The specific firing method is as follows: (1) Pulping: Grind the raw materials and water according to the formula (ball mill, 100r / min, grinding time is 15min) and sieve (300 mesh) to obtain glaze slurry; wherein, the mass ratio of raw materials to water is controlled to be 1:0.9; the mass ratio of raw materials to grinding balls is 1:1.8; (2) Aging: The glaze slurry is placed in a glaze cup, sealed with plastic wrap, and left to stand at 30℃ for 20 hours; (3) Glazing: After stirring the aged glaze slurry evenly, glaze it on the surface of the body (glaze by dipping: first wipe the dust on the surface of the unglazed ceramic body with a damp sponge, and add water as appropriate. After the surface of the ceramic body is dry, glaze it. Each time, immerse the ceramic body in the glaze for 8-10 seconds. You can immerse it multiple times to get a glazed body (glaze layer thickness 1.5mm). (4) Firing: The air-dried glazed body is fired in an oxidizing atmosphere (air) (first, the temperature is increased to 960℃ at a rate of 5.06℃ / min; then increased to 1120℃ at a rate of 1.6℃ / min; then increased to 1200℃ at a rate of 4℃ / min; then increased to the maximum firing temperature of 1230℃ at a rate of 0.5℃ / min and held for 30 min; finally, the temperature is decreased to 1130℃ at a rate of 3.33℃ / min and held for 60 min), and then cooled in the furnace (10℃ / min) to room temperature to obtain a silver oil-spot glaze (sample as shown). Figure 1 (As shown in number 3).

[0039] The glaze has a dark brown base color. The main area of ​​the glaze features a denser distribution of oil droplets and crystals, with small and large crystals interspersed. In some areas, the oil droplets are relatively sparse, giving the glaze a strong vitreous texture overall. The oil droplets are well-formed and contrast sharply with the base color, demonstrating excellent crystallization uniformity.

[0040] Example 4

[0041] A silver oil-drop glaze based on vanadium-titanium magnetite is prepared from the following raw materials in weight percentages: 18 parts potassium feldspar, 37 parts sodium feldspar, 10 parts kaolin, 10 parts quartz, 6 parts calcite, 5 parts talc, 3 parts borax, 6.1 parts vanadium-titanium magnetite, 2.3 parts Cr2O3, and 2.6 parts CoCO3. The specific firing method is as follows: (1) Pulping: Grind the raw materials and water according to the formula (ball mill, 250 r / min, grinding time is 12 min) and sieve (250 mesh) to obtain glaze slurry; wherein, the mass ratio of raw materials to water is controlled to be 1:0.8; the mass ratio of raw materials to grinding balls is 1:2; (2) Aging: The glaze slurry is placed in a glaze cup, sealed with plastic wrap, and left to stand at 25°C for 28 hours; (3) Glazing: After stirring the aged glaze slurry evenly, glaze it on the surface of the body (glaze by dipping: first wipe the dust on the surface of the unglazed ceramic body with a damp sponge, and add water as appropriate. After the surface of the ceramic body is dry, glaze it. Each time, immerse the ceramic body in the glaze for 8-10 seconds. You can glaze it multiple times) to obtain a glazed body (glaze layer thickness 2mm). (4) Firing: The air-dried glazed body is fired in an oxidizing atmosphere (air) (first, the temperature is increased to 960℃ at a rate of 5.06℃ / min; then increased to 1120℃ at a rate of 1.6℃ / min; then increased to 1200℃ at a rate of 4℃ / min; then increased to the maximum firing temperature of 1230℃ at a rate of 0.5℃ / min and held for 30 min; finally, the temperature is decreased to 1120℃ at a rate of 3.3℃ / min and held for 30 min), and then cooled in the furnace (10℃ / min) to room temperature to obtain a silver oil-spot glaze (sample as shown). Figure 1 (As shown in number 4).

[0042] The glaze is dark black with uniformly sized and regularly distributed silver crystal spots that gradually increase in size from the periphery to the center, blending naturally with the base glaze. Despite the presence of obvious pinholes, the glaze surface is smooth to the touch and reflects light to present a metallic silver texture.

[0043] Comparative Example 1

[0044] An oil-spot glaze, with the same raw material formula and firing method as Example 1, differs only in that the weight of kaolin is changed to 8 parts, to obtain the oil-spot glaze (sample as shown). Figure 2 As shown in Figure 1).

[0045] The glaze is a deep black, smooth and even overall, with a weak vitreous luster and a semi-matte finish. There are some tiny glaze bubbles and impurities in some areas, and the oil droplets and crystal spots are not fully precipitated. Only sparse, fine silver-gray dot-like crystal spots can be seen at the edges, while the central area has a uniform deep black background with no obvious crystal phase aggregation.

[0046] Comparative Example 2

[0047] An oil-spot glaze, with the same raw material formula and firing method as Example 1, differs only in that the weight percentage of albite is changed to 30 parts, to obtain the oil-spot glaze (sample as shown). Figure 2 (As shown in number 2).

[0048] The glaze has a dark blackish-brown base color with a strong vitreous luster. The oil droplet crystals are small, dense, and unevenly distributed, with a silvery-gray tone that contrasts softly with the base color. There are slight glaze flow marks at the edges, and the glaze surface has obvious defects such as pinholes.

[0049] Comparative Example 3

[0050] An oil-spot glaze, fired using the same method as in Example 1, differs only in that vanadium-titanium magnetite in the formula is replaced with Fe2O3. The resulting oil-spot glaze sample is shown below. Figure 2 As shown in number 3.

[0051] The glaze has a deep black base and a warm, glassy luster. The oil droplet crystals are distributed in patches, affecting the overall effect of the oil droplet pattern. The glaze surface is smooth and free of cracks, but noticeable porosity defects are present.

[0052] Comparative Example 4

[0053] An oil-spot glaze, fired using the same method as in Example 1, differs only in that 0.1 parts of TiO2 are added to the formula. The resulting oil-spot glaze sample is as follows. Figure 2 As shown in number 4.

[0054] The glaze has a dark brown base color and a strong vitreous luster. The oil droplet-like crystal spots are mainly round or nearly round, unevenly distributed, with large and small crystal spots interspersed, but the color rendering effect is not obvious. There are obvious pinholes on the surface, and the edge contours are slightly irregular.

[0055] Comparative Example 5

[0056] An oil-spot glaze, fired using the same method as in Example 1, differs only in that the vanadium-titanium magnetite in the formula is replaced with Yunnan magnetite. The resulting oil-spot glaze sample is shown below. Figure 2 As shown in number 5.

[0057] There are no oil droplets present, but the glaze base is entirely black and glossy, with a strong glassy luster, and is smooth and flat.

[0058] Experimental example: The oil-drop glazes prepared in Examples 1-4 and Comparative Examples 1-5 were tested for color difference (SC-80C fully automatic colorimeter), gloss (WGG60 gloss meter), thermal shock resistance index (GB / T 34251-2017), scratch resistance (GB / T3298-2022), and chemical resistance (GB / T 5003-2023). The results are shown in Table 2.

[0059] Table 2 Performance test data of oil-spot glaze

[0060] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A silver oil-drop glaze formulation based on vanadium-titanium magnetite, characterized in that, It is prepared from the following raw materials in weight percentages: 15-20 parts potassium feldspar, 35-45 parts sodium feldspar, 10-15 parts kaolin, 8-10 parts quartz, 6 parts calcite, 5 parts talc, 3 parts borax, 6.1 parts vanadium-titanium magnetite, 2.3-2.8 parts Cr2O3, and 2.6 parts CoCO3.

2. A method for firing the silver oil-spot glaze according to claim 1, characterized in that, Includes the following steps: (1) Pulping: Grind and sieve the raw materials and water weighed according to the formula to obtain glaze slurry; (2) Aging: The glaze slurry is left to stand and age to obtain aged glaze slurry; (3) Glazing: After stirring the aged glaze slurry evenly, glaze it on the surface of the body to obtain a glazed body; (4) Firing: The glazed body after air drying is fired in an oxidizing atmosphere and cooled to room temperature in the furnace to obtain silver oil-spot glaze; the firing process includes: first heating to 950-970℃ at a rate of 4-6℃ / min; then heating to 1110-1130℃ at a rate of 1-2℃ / min; then heating to 1190-1210℃ at a rate of 3-5℃ / min; then heating to the maximum firing temperature of 1220-1240℃ at a rate of 0.4-0.6℃ / min and holding for 25-35min; finally cooling to 1120-1140℃ at a rate of 3.2-3.4℃ / min and holding for 30-60min.

3. The firing method of the silver oil-spot glaze according to claim 2, characterized in that, In step (1), the mass ratio of the raw material to water is 1:0.7-0.

9.

4. The firing method of the silver oil-spot glaze according to claim 2, characterized in that, In step (1), a ball mill is used for grinding; preferably, the mass ratio of raw material to grinding balls is 1:1.8-2.

2.

5. The firing method of the silver oil-spot glaze according to claim 2, characterized in that, In step (1), the grinding speed is 400-450 r / min and the grinding time is 10-15 min.

6. The firing method of the silver oil-spot glaze according to claim 2, characterized in that, In step (1), after grinding, the material is passed through a 200-300 mesh sieve.

7. The firing method of the silver oil-spot glaze according to claim 2, characterized in that, In step (2), the aging temperature is room temperature and the time is 20-28h.

8. The firing method of the silver oil-spot glaze according to claim 2, characterized in that, In step (3), the glaze thickness is controlled to be 1.5-2.0 mm when glazing.

9. The firing method of the silver oil-spot glaze according to claim 2, characterized in that, In step (4), the oxidizing atmosphere is air or oxygen.

10. The firing method of the silver oil-spot glaze according to claim 2, characterized in that, In step (4), the furnace cooling rate is 8-15℃ / min.

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