A method for making grey cowhide

Abstract

The invention discloses a method for making gray cowhide, which comprises: 1. selecting raw cowhide; 2. soaking and disinfecting with medicine solution; 3. removing hair and rotten flesh after washing; 4. scraping oil on the shelf; 5. putting ash on the shelf; 6. rinsing and scraping off residual ash and grease; 7. soaking and softening after washing; 8. soaking and repeatedly pushing with softener after drying on the shelf, and repeatedly grinding after unshelf; 9. repeatedly grinding and polishing; 10. applying oil while wet after washing and letting to penetrate to obtain gray cowhide. The invention soaks and softens the cowhide with tanning and softening liquid containing mirabilite, cinnabar and borax, so that the collagen fibers in the cowhide are softened and loosened and maintain a complete three-dimensional structure, so that the color of the product gray cowhide is white and the transparency is high, and the flexibility of the gray cowhide is greatly improved. The obtained gray cowhide is light, soft, translucent, and milky white in appearance, and the leather board is uniform in thickness, hard and tough, which is suitable for making high-end shadow puppets.

Description

Technical Field

[0001] The invention belongs to the technical field of leather preparation, and particularly relates to a method for preparing grey cowhide. Background Art

[0002] With the development of science and technology, contemporary leather processing is generally carried out by machines and equipment. The leather processing technology is mainly divided into four steps: depilation, degreasing, tanning and dyeing. In the process of depilation and degreasing, leather processing companies generally use strong acids and alkalis to achieve the purpose of depilation and degreasing; in the process of tanning, leather processing companies generally use chrome tanning agents or formaldehyde tanning agents to soften the leather. The use of these chemical raw materials will cause pollution to leather products, and the damage to the collagen fiber tissue will lead to the hardening of the cortex, turbid and opaque color, low brightness, easy to be affected by moisture and mold, and other unfavorable results. This type of leather is not suitable for shadow puppet carving, and is even more unfavorable for collection and preservation. However, shadow puppet carving artists generally use machine-made leather (cowhide, donkey skin, sheepskin, etc.) to carve shadow puppet works. This type of leather is hard in texture, easy to crack, and difficult to preserve, which seriously affects the effect of shadow puppet works. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a method for making gray cowhide in view of the shortcomings of the above-mentioned prior art. The method uses a tanning and softening liquid containing sodium sulfate, calcite and borax to soak and soften the cowhide, so that the collagen fibers in the cowhide are softened and loosened and maintain a complete and uniform three-dimensional structure, thereby improving the flexibility of the gray cowhide, and obtaining a light, soft, translucent, milky white, uniformly thick, hard and tough gray cowhide, thereby ensuring the quality of the shadow puppet carved from the gray cowhide, and solving the problem that the conventional machine-made cowhide has a dark color, low light transmittance, large and uneven thickness, and poor flexibility, resulting in poor quality of the shadow puppet.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for making gray cowhide, characterized in that the method comprises the following steps:

[0005] Step 1: Select fresh raw hides of Guanzhong yellow cattle aged one to three and a half years old as raw hides;

[0006] Step 2: soaking and disinfecting the cowhide selected in step 1 in a solution prepared by lime water and caustic soda;

[0007] Step 3: first, wash the cowhide after soaking and disinfection with salt and ethanol solution, then remove the hair with lime water, and then scrape off the rotten flesh with a knife;

[0008] Step 4: Put the cowhide from which the rotten flesh has been removed in step 3 on a rack and scrape off the oil;

[0009] Step 5: Place the cowhide from step 4 under the rack and put it on the ash;

[0010] Step 6: Rinse the cowhide treated with plant ash in step 5 with a saponin solution, and scrape off the residual plant ash and grease on the cowhide;

[0011] Step 7: repeatedly wash the cowhide washed and scraped in step 6 with clean water, and then soak it in a tanning and softening liquid containing sodium sulfate, calcite and borax to soften it;

[0012] Step 8: Put the cowhide softened by soaking in step 7 on the rack, stretch it flat and dry it, then soak it in softener and push it repeatedly, and polish it repeatedly with sandpaper after taking it off the rack;

[0013] Step 9: Wrap the ash in cotton cloth and tie it tightly to obtain an ash bag, and use the ash bag to repeatedly grind and polish the cowhide that has been repeatedly polished in step 8;

[0014] Step 10: Use clean water to clean the cowhide that has been repeatedly polished in step 9, and apply sesame oil or castor oil on the surface of the cowhide while it is still wet, and then maintain it at 40° C. to 50° C. to allow it to penetrate, so as to obtain gray cowhide.

[0015] The method comprises the following steps: firstly placing the selected raw material cowhide in a medicine prepared by lime water (a clear aqueous solution of calcium hydroxide) and stinking caustic soda (sodium sulfide) for soaking and disinfection, so as to kill bacteria and worm eggs attached to the surface of the cowhide, thereby laying a foundation for subsequent processes; then spreading the cowhide flat on a plate with the inside of the cowhide facing upward, sprinkling a layer of salt on it, spraying a layer of medical alcohol with a volume fraction of 75%, and rubbing the cowhide repeatedly, so that the salt and alcohol fully and evenly enter the epidermis and subcutaneous tissue layer of the cowhide, so that the stratum corneum in the epidermis and the collagen fibers, elastic fibers and fat cells in the subcutaneous tissue layer are softened and loosened, which is conducive to the smooth progress of the subsequent depilation and scraping process; a 5% lime water solution is configured in a ceramic container or a stainless steel container, heated to 50°C, and then the washed cowhide is placed in the container for soaking for 1 hour, taken out and spread on the plate, a special scraper is used to complete the depilation work, and the rotten flesh on the cowhide is gently scraped off, and then the scraper is used to scrape off excess fat oil.

[0016] The method comprises the following steps: the cowhide after oil is scraped off the shelf is immersed in clean water for repeated washing and drying, and then flattened on a layer of plant ash (usually with a thickness of 5 cm), and a layer of plant ash is covered on the surface of the cowhide, and the alkaline plant ash (main component of which is potassium carbonate) is used to act on the surface of the cowhide, which not only plays a role in corrosion prevention and oil removal, but also makes the cowhide transparent and increases its transparency. Then, a soapnut solution is used for washing, and the soapnut is used to neutralize the residual plant ash, and the residual plant ash and grease on the cowhide are scraped off, thereby improving the cleanliness of the cowhide.

[0017] The present invention soaks cowhide in a tanning and softening solution containing sodium sulfate, calcite and borax to soften it, and utilizes sodium sulfate, calcite and borax to act on collagen fibers in the dermis of the cowhide to soften and loosen the collagen fibers while maintaining a three-dimensional structure, thereby replacing the traditional tanning agent using concentrated acid and alkali or containing the pollutant chromium, which causes the collagen fibers in the cowhide to break, thereby avoiding excessive softening and loss of flexibility of the cowhide after tanning, improving its flexibility while achieving tanning and softening, and improving the uniformity and stability of the tanning; at the same time, avoiding the problem of turbid color and reduced transparency of the cowhide due to the breakage of collagen fibers in the cowhide.

[0018] The present invention continues to put the soaked and softened cowhide on the rack to stretch and dry, first soak it with a softener and then use a wooden push plate to push the cowhide repeatedly from both sides with force and uniformity to thoroughly remove the fat remaining on the surface of the cowhide and soften the cowhide, further improving the flexibility of the cowhide; then take it off the rack and repeatedly polish it with sandpaper to remove the residual impurities on the surface of the cowhide, improve the flatness, softness and transparency of the cowhide. Next, the present invention uses a plant ash bag to repeatedly push and polish the repeatedly polished cowhide, and further polish and remove the fine residues on the surface of the cowhide. Finally, after washing with clean water, apply sesame oil or castor oil on the surface of the cowhide while it is still wet and maintain it at 40℃~50℃ to allow it to penetrate. This allows the applied sesame oil or castor oil to smoothly enter the pores of the cowhide when the pores are open, lubricating the dermis of the cowhide, which not only improves the softness of the cowhide, but also brightens it. At the same time, the amount of sesame oil or castor oil applied needs to be controlled to ensure the flexibility and transparency of the cowhide, and to avoid the inability to color the subsequent gray cowhide due to excessive oil application during the process of making shadow puppets.

[0019] The above-mentioned method for making gray cowhide is characterized in that the mass content of lime water in the medicine in step 2 is 2%, the mass content of caustic soda is 1% to 1.6%, and the soaking and disinfection time is 3 to 5 days in spring and summer, and 7 to 15 days in autumn and winter.

[0020] The method for making gray cowhide is characterized in that the specific process of applying wood ash in step five is: after the cowhide is taken off the shelf after the oil is scraped, the inside and outside are covered with wood ash, and a cloth is covered on the wood ash to keep it in a steaming state for 7 days.

[0021] The above-mentioned method for making gray cowhide is characterized in that, as described in step one, the wood ash in step five is ashes obtained by burning buckwheat stalks or trees.

[0022] The above-mentioned method for making gray cowhide is characterized in that the mass content of Glauber's salt in the tanning and softening liquid in step seven is 4%, the mass content of calcite is 2%, and the mass content of borax is 2%; the soaking and softening time is 5 days.

[0023] The above-mentioned method for making gray cowhide is characterized in that the drying in step eight is air-drying or shade-drying, and direct exposure to the sun is avoided; after being taken off the shelf, 500 mesh, 800 mesh and 1200 mesh sandpaper are used in sequence for repeated polishing.

[0024] The above-mentioned method for making gray cowhide is characterized in that the softener described in step eight is composed of gallnut extract, alum and salt, and the mass content of the gallnut extract in the softener is 2% based on gallnut, the mass content of alum is 5%, and the mass content of salt is 2%. The gallnut extract is prepared by soaking the gallnut in 40°C water for 12 hours.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] 1. The present invention uses a tanning and softening liquid containing sodium sulfate, calcite and borax to soak and soften the cowhide, so that the collagen fibers in the cowhide are softened and loosened and maintain a complete three-dimensional structure, thereby avoiding the problem that the collagen fibers in the cowhide are broken and lose their flexibility due to concentrated acid and alkali or tanning agents containing chromium as a pollutant, so that the product gray cowhide is white in color and highly transparent, and the flexibility of the gray cowhide is greatly improved.

[0027] 2. The present invention uses salt and alcohol to rub the hide to soften and loosen the stratum corneum, collagen fibers, elastic fibers and fat cells in the hide, which is beneficial to the smooth depilation and scraping of the hide, while avoiding the damage to the collagen fibers, further ensuring the complete shape of the gray hide and improving its flexibility.

[0028] 3. The present invention soaks the cowhide with a softener consisting of gallnut extract, alum and salt and pushes it repeatedly from both sides to further soften the cowhide and improve the flexibility of the gray cowhide. It is combined with the use of wood ash bags for grinding and polishing to improve the surface smoothness of the cowhide while avoiding damage to its organizational structure.

[0029] 4. The gray cowhide obtained by the production method of the present invention has a light, soft, translucent appearance and is milky white. The thickness of the leather board is uniform, hard and tough. After testing, the collagen fiber tissue in the gray cowhide is intact. The shadow puppet carved with the gray cowhide is not easy to break. Even if it is rolled up, it will be flat as before after unfolding. The leather making process can make the shadow puppet not change color for hundreds of years. It is flat, white, translucent and very distinctive. It has a high inheritance and circulation value, is suitable for long-term collection, and is a special cowhide for making high-end shadow puppets.

[0030] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a scene diagram of the soaking and disinfection process in the gray cowhide production method in Example 1 of the present invention.

[0032] Figure 2 This is a scene diagram of the depilation and fleshing process in the method for producing gray cowhide in Example 1 of the present invention.

[0033] Figure 3 This is a scene picture of the oil scraping process on the shelf in the method for producing grey cowhide in Example 1 of the present invention.

[0034] Figure 4 This is a scene diagram of the process of applying plant ash in the method for making gray cowhide in Example 1 of the present invention.

[0035] Figure 5 This is a scene diagram of the process of scraping off residual wood ash and grease on the cowhide in the method for making gray cowhide in Example 1 of the present invention.

[0036] Figure 6 This is a scene diagram of the softener soaking and repeated pushing process in the gray cowhide production method in Example 1 of the present invention.

[0037] Figure 7 This is a physical picture of the gray cowhide produced in Example 1 of the present invention.

[0038] Figure 8a The present invention is a real-object picture of gray shadow puppets of the Qing Dynasty carved from gray cowhide.

[0039] Figure 8b A real picture of a colored shadow play carved from grey cowhide produced by the present invention.

[0040] Figure 9a This is a physical picture of the gray cowhide produced in Example 1 of the present invention.

[0041] Figure 9b This is a physical picture of the existing machine-made cowhide.

[0042] Fig.10a This is an electron microscopic image of the gray cowhide produced in Example 1 of the present invention.

[0043] Fig.10b This is the electron micrograph of the existing machine-made cowhide. DETAILED DESCRIPTION

[0044] Example 1

[0045] This embodiment includes the following steps:

[0046] Step 1: Select fresh raw hides of Guanzhong yellow cattle aged one to three and a half years old as raw hides;

[0047] Step 2: Soak the cowhide selected in step 1 in a solution of lime water and caustic soda for disinfection. Figure 1As shown; the mass content of lime water in the medicine is 2%, the mass content of caustic soda is 1% to 1.6%, and the soaking and disinfection time is 3 to 5 days in spring and summer, and 7 to 15 days in autumn and winter;

[0048] Step 3: First, wash the cowhide after soaking and disinfection with salt and ethanol solution, then use lime water to remove the hair, and then use a knife to scrape off the rotten flesh. Figure 2 As shown;

[0049] Step 4: Put the cowhide from which the rotten flesh has been removed in step 3 on the rack to scrape off the oil. Figure 3 As shown;

[0050] Step 5: Put the cowhide that has been scraped of oil in step 4 under the rack and put it on the ash. Figure 4 As shown; the specific process of applying plant ash is: after the oiled cowhide is removed from the shelf, the inside and outside are covered with plant ash, and the plant ash is covered with cloth and suffocated for 7 days. The plant ash is the ashes obtained by burning buckwheat stalks or trees;

[0051] Step 6: Rinse the cowhide treated with plant ash in step 5 with a saponin solution, and scrape off the remaining plant ash and grease on the cowhide. Figure 5 As shown;

[0052] Step 7, repeatedly washing the cowhide washed and scraped in step 6 with clean water, and then soaking it in a tanning and softening liquid containing mirabilite, calcite and borax for 5 days; the mass content of mirabilite in the tanning and softening liquid is 4%, the mass content of calcite is 2%, and the mass content of borax is 2%;

[0053] Step 8: Put the leather that has been softened in step 7 on the rack and stretch it flat and air dry or dry it in the shade, avoid direct sunlight, then soak it in softener and push it repeatedly. Figure 6 As shown, after being taken off the shelf, 500 mesh, 800 mesh and 1200 mesh sandpaper are used to repeatedly polish; the softener is composed of gallnut extract, alum and salt, and the mass content of the gallnut extract in the softener is 2% based on the gallnut, the mass content of alum is 5%, and the mass content of the salt is 2%, and the gallnut extract is prepared by soaking the gallnut in 40° C. water for 12 hours;

[0054] Step 9: Wrap the ash in cotton cloth and tie it tightly to obtain an ash bag, and use the ash bag to repeatedly grind and polish the cowhide that has been repeatedly polished in step 8;

[0055] Step 10: Use clean water to clean the cowhide that has been repeatedly polished in step 9, and apply sesame oil or castor oil on the surface of the cowhide while it is wet, and then maintain it at 40℃~50℃ to allow it to penetrate. The gray cowhide produced is as follows: Figure 7 shown.

[0056] The physical properties of the gray cowhide prepared in this example were compared with those of the existing machine-made cowhide. Figure 9a to Figure 9b As shown in Table 1 below.

[0057] Table 1

[0058]

[0059]

[0060] from Figure 9a to Figure 9b As can be seen from Table 1, compared with the current conventional machine-made cowhide which has dark color, low light transmittance, large and uneven thickness, poor flexibility and partially damaged fiber tissue structure, the gray cowhide produced by the method of the present invention is lighter in color and more transparent, thinner and more uniform in thickness, and its fiber tissue is basically intact, so it has better flexibility.

[0061] Figure 8a This is a real picture of the gray shadow puppet of the Qing Dynasty carved from gray cowhide made in this embodiment. Figure 8b The actual picture of the colored shadow puppet carved from gray cowhide made by the present invention is from Figure 8a and Figure 8b It can be seen that the gray cowhide prepared by the method of the present invention is thin, soft, translucent, uniform in thickness, hard and tough. The gray shadow puppet carved from the gray cowhide has smooth lines, white color, and no fading or breakage. The colored shadow puppet carved from the gray cowhide is evenly colored, thin and tough, and suitable for long-term collection.

[0062] Fig.10a This is the electron microscopic structure diagram of the gray cowhide produced in this embodiment. Fig.10b This is the electron microscopic structure diagram of the existing machine-made cowhide. Fig.10a and Fig.10b By comparison, it can be seen that the collagen fiber tissue in the existing machine-made cowhide presents irregular fracture morphology and uneven distribution, resulting in poor toughness of the machine-made cowhide, which is not conducive to carving shadow puppets and collection and preservation. The collagen fiber tissue in the gray cowhide produced in this embodiment is intact and evenly arranged, which greatly improves the flexibility of the gray cowhide. Therefore, the carved shadow puppets are not easy to break and are more suitable for collection and preservation.

[0063] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for making grey cowhide, characterized in that: The method comprises the following steps: Step 1: Select fresh raw hides of Guanzhong yellow cattle aged one to three and a half years old as raw hides; Step 2: soaking and disinfecting the cowhide selected in step 1 in a solution prepared by lime water and caustic soda; Step 3: first use salt and ethanol solution to clean the cowhide after soaking and disinfection, then use lime water to remove hair, and then use a knife to scrape off the rotten flesh; Step 4: Put the cowhide from which the rotten flesh has been removed in step 3 on a rack and scrape off the oil; Step 5: Place the cowhide from step 4 under the rack and put it on the ash; Step 6: Rinse the cowhide treated with plant ash in step 5 with a saponin solution, and scrape off the residual plant ash and grease on the cowhide; Step 7: repeatedly wash the cowhide washed and scraped in step 6 with clean water, and then soak it in a tanning and softening liquid containing sodium sulfate, calcite and borax to soften it; Step 8: Put the cowhide softened by soaking in step 7 on the rack, stretch it flat and dry it, then soak it in softener and push it repeatedly, and polish it repeatedly with sandpaper after taking it off the rack; Step 9: Wrap the ash in cotton cloth and tie it tightly to obtain an ash bag, and use the ash bag to repeatedly grind and polish the cowhide that has been repeatedly polished in step 8; Step 10: Use clean water to clean the cowhide that has been repeatedly polished in step 9, and apply sesame oil or castor oil on the surface of the cowhide while it is still wet, and then maintain it at 40° C. to 50° C. to allow it to penetrate, so as to obtain gray cowhide.

2. The method for making gray cowhide according to claim 1, characterized in that: The mass content of lime water in the medicine in step 2 is 2%, the mass content of caustic soda is 1% to 1.6%, and the soaking and disinfection time is 3 to 5 days in spring and summer, and 7 to 15 days in autumn and winter.

3. The method for making gray cowhide according to claim 1, characterized in that: The specific process of applying the plant ash in step 5 is: after the cowhide is taken off the shelf after the oil is scraped, the inside and outside are covered with plant ash, and a cloth is covered on the plant ash to keep it in a stale state for 7 days.

4. The method for making gray cowhide according to claim 1, characterized in that: The wood ash in step 5 is the ash obtained by burning buckwheat stalks or trees.

5. The method for making gray cowhide according to claim 1, characterized in that: In step seven, the mass content of mirabilite in the tanning and softening liquid is 4%, the mass content of cinnabar is 2%, and the mass content of borax is 2%; the soaking and softening time is 5 days.

6. The method for making gray cowhide according to claim 1, characterized in that: The drying in step eight is air-drying or shade-drying, and avoid direct exposure to the sun; after being taken off the shelf, 500 mesh, 800 mesh and 1200 mesh sandpaper are used in turn for repeated polishing.

7. The method for making gray cowhide according to claim 1, characterized in that: The softener described in step eight is composed of gallnut extract, alum and salt, and the mass content of the gallnut extract in the softener is 2% based on gallnut, the mass content of alum is 5%, and the mass content of salt is 2%. The gallnut extract is prepared by soaking the gallnut in 40° C. water for 12 hours.

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