Traditionally, plaster is a mortar composed by a binder, which is usually made of calcareous or siliceous sand (natural or crushed rock), and additives like fibers, expanded glass or synthetic resins, which are used to improve the characteristics of the material like thermal insulation, its perspiring capability or its workability. Plasters are divided according to the binder used in the mix: lime, cement, gypsum or clay. The choice of the type of plaster is essential for its durability. Plasters for external walls, which are exposed to harsh weather conditions, are made of hydraulic lime or cement, which are more resistant, whereas internal surfaces are usually covered with lime mortars or gypsum when not exposed to humidity. Traditional plastered walls have three handmade layers called the “render”, the “float” and the “set” plasters. The render is prepared with thicker aggregate and a high dosage of binder and it is used to form a supporting layer for the outer ones. The float, or floating coat, has a lower amount of binder and it is used as a filler and it makes the plaster waterproof. The last layer is the set, or setting coat, which is made of fine grain sand mortar. There could be a further additional aesthetical layer. Eventually there could also be an additional decorative putty layer. Nowadays, however, premixed plasters are preferred instead of the traditional ones. Premixed plasters are layered with plastering machines that speed up the work remarkably and reduce labor costs. In our Plasters section on Archiproducts you can find all the products and the complements to finish your external and internal walls.