This causes a chemical cross-linking and hardening of the exposed areas of the stencil. When washed with a spray of water, these hardened areas stay adhered to the mesh, and the areas blocked by the opaque image on the film, which has shielded the underlying stencil from the UV light, wash out with a light spray of water. The end result should leave an image identical to the film positive image as open areas in the mesh, surrounded by a layer of hardened stencil adhered to the mesh. Components of the exposure process are a light source, a vacuum frame, and a washout booth . An exposure calculator, a light integrator or a timing device , plus hot and cold water are also required.
Indirect stencils require a developing tray and peroxide developer.
The light source supplies UV spectrum light rays in the 330-440 nanometer range. This causes the photosensitised elements contained in the emulsion to react. Other light sources include the sun, and direct projection devices. The light sources can be run on a timer for a predetermined time at a specific distance. More accurate is a light integrator, which reads the exact amount of specifically filtered UV light reaching the screen over the course of the exposure.