The purpose of removing fire poison from black plaster is as follows

The matrix materials of black plaster are mainly vegetable oil and red lead. Sesame oil is the best vegetable oil, and its finished product has a smooth appearance. Cottonseed oil, soybean oil, vegetable oil, peanut oil, etc. It can also be used, but it is easy to produce foam during preparation and should be removed in time. Red lead, also known as Zhang Dan, Red Lead, Huang Dan, Dongdan and Dan Tao, is an orange-red amorphous powder, and its main component is lead tetroxide, with a content of over 95%. The red lead used for preparation should be dry, without moisture absorption and caking. The main component of black plaster matrix is higher fatty acid lead salt. In the preparation process, Chinese medicinal materials are extracted and refined, and then red lead is added into the refined oil to react to generate fatty acid lead salt, which promotes the further oxidation, polymerization and thickening of oil and forms paste. The purpose of removing the "fire poison" of black plaster is to remove aldehydes, ketones, lower fatty acids and irritating small molecular products. The answer is BCE.