Traditional screen printing, or serigraphy, is essentially the process of applying ink through a stencil. 

The 'screens' are a fine-mesh that’s stretched over a rectangular frame and coated in light-sensitive emulsion. The design is split into colours, with each colour printed onto transparent film and exposed onto a separate screen. Exposing the screen makes a stencil of the design, only allowing ink to pass through the exposed design. 

A screen is then placed onto the print surface, and ink is pressed through the mesh, forming the print. This process is repeated for each additional colour, with the use of a high-temperature flash in-between. 

After the print is applied in each colour, the item is placed through a heat tunnel to cure and dry the ink onto the garment. 

Imagine for a second that the mesh stencil is a flour sifter, and you’ve glued over some of the holes in the sifter, so that flour only comes out of certain holes, this is exactly the same principle for traditional silk screen printing.

This method is used commercially to print paper, fabric, garments, glass, ceramics, and also superfine computer components like circuit boards.