Silk-screen printing is a type of screen printing, in which special monofilament polyester, polyamide (nylon) or metal mesh with a frequency of 4–400 threads / cm and a thickness of about 40–500 microns is used as a plate material. Usually white space elements are formed directly on the grid by a photochemical method. For the manufacture of the printing form can be used as a dry film photo layer (capillary film), and liquid emulsion, dried on the grid after application, as well as a combination of these two methods. In the normal state, the photo layer is washed off with water. After exposure with UV radiation (wavelength 360-420 nm) the photo layer polymerizes and ceases to be washed off with water, except of areas covered with a positive image. Spots with washed photo layer become printed elements. In most cases the exposure is carried out by contact method.
The printing itself is made with special squeegees with a polyurethane sheet that leading it along the upper (squeegee) side of the grid (stencil). Thus, the paint is strictly metered and passes through the grid in those places where there is no emulsion.
As a rule the printing forms (grids) after printing go on refresh (washing of the photopolymer layer) and then are used for printing again.
Due to its technological features silk-screen printing allows to print on flat and cylindrical surfaces as well. Now screen printing is used not only in printing but also in textile, electronic, automotive, glass, ceramic, and other industries.
One of the features of silk-screen printing is the ability to get a thick paint layer from 8-10 microns to 1000 or more (for an offset printing it is 1-2 microns) with impressive color covering and brightness. You can also widely use special effects – glitters, convex printing, imitation of velvet or rubber. It is possible as directly printing onto the surface, as transfer to an intermediate carrier (for example – transfer paper) with subsequent transfer to the product.
Silk-screen printing has various advantages:
- simplicity of the process;
- the ability to print on materials of various types;
- considerable thickness of the applied paint and brightness of color;
- durability of the sealed materials;
- low price for the production of small and medium circulations;
- special screen printing solutions do not available with other printing methods.