Screen-printing, also called serigraph, was invented 2000 years ago in the Far East.
Originally the screen printer's screen was made of silk and a paper stencil was stitched onto it to control the printed area. Cut to the early 1900s. Screen-printing is re-vamped and has since become a common method for printing on textiles. Screen-printing is most often seen on t-shirts and the screens are usually made of a monofilament mesh along with emulsion to make the stencil.

The screen is coated with emulsion and allowed to dry and harden. The emulsion used is very light sensitive so coating the screen and then exposing it to light makes the stencil.

If you do not expose it to light, the emulsion will remain water-soluble and can be washed out but once you expose it to light water will not dissolve it. Once the stencil is designed and put on the screen, you are ready to apply it to your t-shirt or other textile.