Traders for this type of material are Styropor (expanded polystyrene), Styrodur or Styrofoam (extruded polystyrene) and Rohacell (polyurethane) among others.
The rigid foam is used to cut volumes or surfaces, especially in conceptual and workmanship models, or when designing special layouts in the field of object design. Foams whose names start with “styro” can be easily cut by a knife or a hot wire, usually made of nickel (“thermal closure”); in order to work with more precision, a pile and sandpaper can be achieved. Rohacell plates should not be cut with thermal closure, but rather with a cutter or a simple closure. It is so rigid that it can be brushed, perforated and polished (in case of using a sander it is essential to put a mask!).
We need special adhesives for each product, otherwise we risk that the solvent should make holes in the foam! It is preferable to make a test first! Surfaces can be painted with any water-soluble paint. In the case of the application of varnishes and synthetic resins, the surface of the foam should be covered with a water-soluble layer and then filleted.
The brilliance caused at the edges of the Rohacell volumes usually disturbs when the model is photographed.
Styropor, Styrodur and Styrofoam boards can be found at 50 x 100 cm in thickness from 10 to 100 mm.
Rohacell provides three qualities of boards. Boards of 125 x 62.5 cm (1 to 3 mm thick) or 250 x 125 cm (from 4 to 40, or even 65 mm thick).