What do we know about gypsum?
This material is very plastic, it is applied to almost all kinds of surfaces, quickly hardens and is easily processed. It is used in a variety of sectors of the economy: as a fertilizer, components of cellulose and paper production, ingredients for the production of paints and enamels. And, of course, the burnt powder is used for casting of internal elements of a building decor, as an astringent material in construction.
There are special types of building brands. High-strength mixtures and gypsum-cement( pozzolanic) binders are produced. Working with gypsum does not cause much complexity. Hardening, it forms a very easy to handle stone-like mass. Therefore, it is widely used for the production of all kinds of handicrafts. Here, its obvious advantage is the high fluidity of the solution, which is very convenient for casting products.
Fine-grained structure makes gypsum an indispensable material for the creation of all possible injection molds, also with the addition of high-temperature components.
The drawbacks include its low strength and hygroscopicity, so it is undesirable to use such materials in rooms with high humidity. If necessary, apply waterproof coatings. Thus it is necessary to consider, how correctly to work with a gypsum. The porous structure facilitates the absorption of the coating applied directly to the surface. Therefore, it is necessary to pre-primer such a surface under a suitable coating.
How to dissolve gypsum - a few preliminary remarks
You should also note the time of work with the solution. Here in many respects plays a role, in what proportions to plant gypsum. But, in general, the time of its hardening is from 20 minutes to an hour. Reuse of already begun to harden gypsum is undesirable, becausethis affects the quality of work for the worse. This circumstance must be taken into account before using gypsum. It is necessary to prepare a solution with its content only for the volume of work that can be performed for a specified period of time.
Practice shows that it has not yet been possible to find a full replacement, so you need to know how to properly dissolve the gypsum. It is always useful for small repairs, shpatlevochnyh works, etc. When preparing a gypsum test, you need to take into account the proportions. With more powder, the dough gets thicker, the material slightly hardens. And vice versa. We can say that for a more dense solution the ratio of gypsum and water will be about 2: 1, respectively.
Average density( call it normal) will be obtained if about a half kilogram of the mixture is added to a liter of water. A completely liquid dough, or rather a solution, is obtained in the ratio of water and gypsum one to one.
Mix gypsum yourself
When preparing a plaster solution, you need to know how to knead the gypsum correctly. Here the main thing is to pour the powder into the water in the above proportions with constant stirring. And not vice versa. And add it should be evenly and gradually, not allowing the formation of lumps. It is necessary to know that it is possible to release a small amount of heat.
In addition, too long stirring is undesirable, becauseleads to the phenomenon of rejuvenation. To work with gypsum, a tool made of stainless steel or hardwood is recommended, it is possible to use special rubber spatulas, etc. As already mentioned, the time of work with gypsum solution is rather limited. Therefore, the technology of working with gypsum, in addition to determining the "portioning" of its preparation, must also take into account the "layering" of processing associated with this.
It is necessary to prepare the already processed part( until full hardening) with special incisions. With a long break in work, the applied and hardened layer should be slightly moistened before applying the next layer of material. If it is necessary to slow down the setting reaction of gypsum, you can use the so-called adhesive water( glue from the mezdra or gelatin solution).The opposite effect can be achieved by adding conventional table salt. In each case, you should experiment with the proportions of the components.