Screen printing involves the use of an open-weave fabric or screen usually made of silk, polyester or stainless steel stretched in a frame. Stencils made by photoetching process are placed on the screen where ink transfer is not desired. A rubber squeegee forces ink through screen and on to the part surface. The process requires periodic cleaning of screens and careful control of ink viscosity. It is an inexpensive technique which can be used to decorate flat or cylindrical plastic parts.