Usually inexpensive, photographic proof from negatives where all colors are shown in blue (or another color) is called a blueline. The negatives used for the printing plates are exposed to a photosensitive paper to produce the image on the blueline. A blueline is a type of contact proof, so named because it is created by having the negative come in contact with a special type of paper.
Additional names for a blueline, based on the color are blackprint, blueprint, brownline, brownprint, and silver print.
Also Known As: contact proof | salt proof | position proof | Dylux (paper brand) | VanDyke | diazo | dyeline | ozalid
Examples: Best used for spot color jobs, a blueline is used primarily to check accuracy and position before plates are made. It shows all text and images (in a single color). Use bluelines to check for smudges or scratches on the film. A blueline is a type of paper proof or position only proof.