This is basically black printed circuit board, with a photoresist, factory deposited on it. A photoresist is a chemical that changes composition when exposed to light. The PCB "Riston" is placed on a flat surface, and your negative artwork is then sandwiched between a sheet of glass and the "Riston" PCB. You can expose PCB pattern and board in broad daylight, however a controlled source of UV is recommended. After the recommended exposure time, you remove the PCB pattern. Where the "Riston" was in shadow the photoresist will not have changed chemical composition. Where it has been exposed it will. You then apply the Developer to complete the process. The copper tracks will still have the "Riston" present, and this must be removed with Stripper CRS-40/5.