The Custom Screen Printing Process, Part 3: Making & Exposing Screens

Screen printing is basically a stencil-based form of printmaking.   In part 3 of this series, we are looking at how the screens are made and turned into a stencil.  The screen is a metal frame with an ultra-fine mesh stretched  drum-tight affixed to it.  The screen is coated with a light-sensitive photo-emulsion, which basically turns it into a giant piece of photographic film, and left in the dark to dry.  Once the emulsion is thoroughly dry, it is ready to have an image exposed into it.  This is where the films come in.  The film is laid on the screen, pressed right against the emulsion.  The screen with film is then exposed to ultraviolet light.  The film acts as a light blocker; the parts of the emulsion that are exposed to the UV light undergo a chemical change, hardening and solidifying.  The parts of the emulsion that are underneath the image on the film, however, will not be exposed to UV light, and therefore will not undergo the same chemical change;  they will remain soft and water-soluble.

At the end of the exposure, a faint ghost image will be visible in the emulsion.  At this point, the exposure is complete and the image must be developed, or washed out.  The screen is blasted thoroughly on both sides with water from a pressure washer, until all of the undeveloped emulsion is completely washed away.  What is left is a stencil that will be used to print the final image on a shirt.  Now, textile ink will only pass through the areas of exposed mesh, making the screen an effective stencil for printing.  Repeat this process for each of the colors or screens that are part of the design, and then we're almost ready for the fun part, printing!