Using A Stouffer Wedge To Determine Intensity of UV Light
A Stouffer Wedge is a strip of continuous tone film with a range of greys between 100% black and 0% white or clear on the strip. It is used to determine the correct amount of UV light needed to harden the photopolymer plate. Light passes through the graded sections in different amounts. Manufacturers of photopolymer plates suggest an ideal Stouffer Wedge reading for their particular type of plate. This reading is intended as a guide when exposing photopolymer plates to film which has been printed at a film lab on an imagesetter. This reading will be different when using film produced through an inkjet or laser printer.
You can also use the Stouffer Wedge to ascertain the intensity of UV light when using different or unfamiliar UV exposure units. By testing the UV unit with a Stouffer Wedge you can see if the new unit is more or less powerful than the one you have been using and adjust your exposure times accordingly. If you are using sunlight to exposure your plates you can do a test Stouffer Wedge exposure to get a reading of the intensity of the UV light.
An imagesetter is a high-resolution output device used in the commercial printing industry that transfers a digital file to film. Imagesetters are becoming obsolete with the move to direct to plate processing.