One of the obvious signs of coating off water is the collapse of the foam and a rise in temperature, with the risk of decomposition of fats and glycerin. The coating of the patch (saponification process) lasts on average 2-3 hours. Initially red mixture gradually changes to whitish gray, and at the end of cooking – to a whitish mass. Cooking patch is considered complete when a small sample, poured into cold water, forms a plastic mass, which when kneaded does not leave marks on the hands and does not stick to the fingers. Next, the patch is freed from the glycerol formed during the hydrolysis of triglycerides of fats. To do this, still hot mass through a metal fine sieve poured into warm water, where it solidifies in the form of threads. This greatly increases the contact surface of the mass with water, which facilitates the washing of glycerol. The patch mass is then transferred to a kneading machine heated by steam, where it is mixed with warm water. Water is drained, after which kneading with water is made several more times. Washed in this way plastar mass again loaded into the coating and heated to 105-110 ° C until the complete removal of water. The finished product with the help of a suppository press rolled out or squeezed into sticks, which are wrapped with parchment paper.
The quality of the resulting patch depends largely on the quality of the original ingredients. It is necessary to ensure that lead oxide does not contain impurities of mealybug, which do not saponify fats, and water was necessarily distilled to avoid the formation of sulfates and carbonates of lead. In addition, by-products (glycerin and wash water) must be completely removed during the plaster production process to prevent the plaster mass from becoming brittle during storage.

Simple lead plaster, in addition to direct use in medicine (for purulent inflammatory skin diseases, coating, carbuncles, etc.) serves as a basis for the preparation of all other types of ordinary plasters. Plasters, which, along with other medicinal substances includes a simple lead plaster, are divided into lead-resin (complex lead plaster) and lead-wax (plaster epilinovyh, mercury and acrihinovyh). Lead-resin plasters. This group includes a complex lead plaster (Emplastrum Plumbi compositum), which has the following composition: 85 parts of simple lead plaster, 10 parts of rosin and 5 parts of turpentine oil. For its preparation fuse lead plaster and rosin, and then to the semi-cooled mass with constant stirring add turpentine. Complex lead plaster is produced in the form of sticks and is used as a mild irritant for purulent inflammatory skin diseases, coating, etc. Lead-wax patches. This group of patches includes epilin, mercury and acrihin patches. Epilin plaster {Emplastrum Epilini) 4% consists of 4 parts epilin, 54 parts simple lead plaster, 5 parts wax, 22 parts anhydrous lanolin and 15 parts water. In the manufacturing process, the simple lead patch is fused with wax and anhydrous lanolin, after which the mass is filtered through a sieve into a container with a stirrer. Epilin is dissolved in distilled water at , weak heating. The resulting solution is emulsified in a warm alloy until the patch mass cools down completely. Epilin patch is used in dermatological practice for hair removal in the treatment of fungal diseases on the scalp. Mercury patch (Emplastrum hydrargyri) consists of 59 parts of concentrated gray mercury ointment with a mercury content of 84-86%, 16 parts of anhydrous lanolin, 150 parts of simple lead patch and 25 parts of yellow wax.