The first is the primary processing, that is, hoof, ear, lip, tail and so on. They are all cut off by hand, stripped of the residual meat and fat on the skin, and then washed off the mud, feces, blood and other dirt stuck to the skin with clear water. Then hang the meat noodles in an outdoor ventilated place or weak sunlight to dry, turn them to 80% dry frequently, pile them up, flatten them with wooden boards and heavy objects, and continue to dry them the next day.

The second step is softening, that is, soaking the dried skin after primary treatment in clean water at room temperature for 16- 18 hours to soften the skin and restore the fresh skin. Then rinse the dirt with clean water, soak it in 3 g/L detergent solution for about 10 minute, rinse it with clean water, and take it out and drain it. When soaking with washing powder, you should remove the connective tissue on the leather board and wash off the dirt on your hair. Fat skin boards can be washed with washing powder in warm water at 35℃ for two or three times, but the action should be fast. Pay attention to stretching the leather board when drying, and the next step can be processed when it is 60% dry. The third is cooking, there are many methods, here I only say that it is more practical at home. How to cook nitrate noodles? . Preparation of nitrate solution: take 10 kg sodium sulfate (mirabilite). Dissolve 5 kg of sodium chloride in 100 kg of water, add 25 kg of flour and stir well. The dosage of nitrate solution is about 10 times the weight of fur. Nitrification: soak the softened fur in nitrate solution, stir and soak it evenly, press heavy objects to immerse it under the liquid surface, and turn it once a day. The curing time depends on the temperature. When the temperature is 15-20℃ in spring and autumn, it is generally soaked for 16-22 days, and when the temperature reaches 30℃ in summer, it can be soaked for about 15 days. The inspection method of the finished product is to fold the leather board in half or squeeze the nitrate solution by hand. If the hide is white and dehydrated well, it means it has been nitrated. Don't touch raw water after the finished product is taken out of the tank, then dry it and shovel it. You can mix the appropriate nitrate solution according to the amount of sheepskin in your house.