文档介绍：石膏模具的制作方法(Method for making plaster mold)
The manufacture of plaster mould
Introduction
The invention of ceramics is of quartz clock - gypsum ground after baking into, the gypsum powder can be purchased in some big city building materials store, but in the small town in rural areas can not buy, only their own processing. The processing method is: the gypsum by grinding pestle, the more detailed the better, then roasted in a pot and burned while fry, burn 800 degrees or so, its quality is no ready-made good.
Gypsum powder, chemically called hemihydrate gypsum or H20 (2CaS04), is formed by the loss of crystalline water 3/4 when the gypsum CaS04 2H20, naturally occurring in large quantities, is heated to 150 degrees ~170 degrees. A mixture of gypsum and water soon forms and becomes Ca~S04 - 2H20. We use gypsum flow of oil liquid into a solid plastic, mold making and firing works, the whole reaction process for about fifteen minutes, will produce a certain heat, gypsum powder and water ratio of about 2:3, too much water, after solidification fastness; if you need to put more strength, gypsum powder.
As has been condensed into the solid gypsum is not reusable, gypsum by liquid condensed into a solid, and there is a time limit, in the mix when gypsum to firing the forming action must be quickly from the start, but also to estimate the amount of gypsum is good, how much to mix.