MASTER reaction injection moulding was first in the spring and Autumn period

Plaster mould was first in the spring and Autumn period, the ancestors with clay or stone carving out as a tool to coin money. Development up to now,the materials and processes are better than in MASTER injection molding supplies the past many advanced, in the material aspect, such as metal, resin, rubber, wood, plaster, several materials only gypsum is relatively easy to processing, no need of professional equipment, only need a knife or pieces of paper or wood, plus some soapy water as isolating agent can. Before making the plaster mold, people need to understand the properties of gypsum, gypsum powder is composed of a gypsum mine in quartz roasting by ground support, building materials stores a lot of big city in general can buy, their processing needs of small town of a class of area, is also the gypsum by grinding pestle, then roasted in a pot, burning fire, when the temperature to 800 degrees can be, but of course the quality no outside sell well. Nature when it comes to gypsum MASTER plastic container moldingpowder, chemically it is called semi  hydrated gypsum and burnt gypsum, it is mixed with water into a paste will soon after solidification, it is based on it by the flow of liquid into plasticity solid production molds and fire works, in the reaction process also generates heat. It should be noted, if too much moisture, will cause the solidified fastness variation condition, if need solid strength, should put the gypsum powder. Due to the condensation of solid gypsum can not be reused, so in the firing process must be fast, and be ready ahead of time and dosage of gypsum. Gypsum and gypsum products all have in common is absorbent, so people invented the slip casting method to make the blank, which is the removal of making plaster mold, another major use of gypsum.