Cooked gypsum powder (2CaSO4 flat 2O), engine oil and talcum powder (prickly heat powder can be used instead). Activity flow 1. Put the cooked gypsum powder into a large porcelain bowl, add a proper amount of cold water (the mass ratio of cooked gypsum powder to water is 10: 13), and stir evenly with a stirring rod to make a flowable paste. 2. Quickly put the gypsum paste into a small wooden box with engine oil on the inner wall, and scrape the surface of the gypsum paste with a scraper. 3. Take a small toy coated with engine oil, quickly embed half of the toy into a small wooden box filled with gypsum paste, and scrape off the surface of gypsum paste with a scraper.
After 4.20 minutes to 30 minutes, after the gypsum paste in the small wooden box is completely solidified, sprinkle some talcum powder on the gypsum surface. 5. Put some cooked gypsum powder in the big porcelain bowl and add water to make gypsum paste. 6. Fill another small wooden box coated with engine oil with gypsum paste, scrape off the surface of gypsum paste with a scraper, cover this wooden box on the previous wooden box, so that the exposed half of the toy is embedded in the gypsum paste, and scrape off the excess gypsum paste with a scraper. 7. In about half an hour, separate the two boxes, take out the small toys and plaster blocks in the two boxes, and a pair of realistic and interesting toy plaster molds will be made. Description and extension 1. Before mixing the cooked gypsum powder with water into gypsum slurry, it is necessary to make preparations for making molds. Make it quickly, otherwise the gypsum paste will easily solidify in different degrees, which will affect the quality of the mold. 2. After the plaster mold is made, it can be used to make many plaster toys, and it can also be used to make molten white wax or colored wax into wax figures. 3. When making gypsum mold, the role of engine oil and talcum powder is to facilitate gypsum demoulding.