Thursday, November 1, 2007
A light sensitive plate of silver or copper is exposed to ultraviolet light passing through a transparency of the desired image. Where the light passes through and exposes the plate, the emulsion hardens and where the light is blocked, the emulsion remains soft. The plate is developed in a soda ash solution which removes the unexposed emulsion. The emulsion that remains on the plate becomes the resist when it is placed in acid thus creating the etched image.