Details:
Summary:
In process camera work, a bump exposure, also known as a no-screen or highlight exposure, is often used in making halftones. When silver-halide crystals are exposed to light, they become more sensitive, and as a result, the main exposure is shortened. In shooting halftones, a bump exposure compresses the screen range and increases highlight contrast by making the highlight dots smaller. When attempting to use a bump exposure with direct emulsion in screen printing, the key factor under consideration is a reduced main exposure. The question asked at the beginning of the experiment was: Could a bump exposure be used to reduce the main exposure, and as a result, would there be less undercutting? The results showed no discernable difference in dot size between the image with a main only exposure and the image with a bump and main exposure. Three possible reasons why undercutting was not reduced have been postulated.