Several techniques to bring the positive emulsion in contact with polymer emulsion. Film belt acts as a drive and overall contact impression device to hold the positive firmly in alignment and contact. Positive film is aligned around the cylinder, the cylinder rotates against the drive film, in front of mercury vapor exposure light. Photo resist- colorless when applied. During developing process dark blue, green or black dye applied to softened resist.
Cells develop cleanly leave exposed copper metal when resist developed away.
Etchant application- roller applied, rotated in bath, paddle splashed and sprayed. Time to etch 2-4 minutes. Direct system- very accurate in color to color register, cell specifications. Not affected by humidity. Engraving can be interrupted, adjusted again and again.