Control Techniques for Photoprinting Operations in Photoengraving.

Control of the photoprinted dot size is important in photoengraving because variation in the amount of dot spread obtained during photoprinting complicates the etcher's task. The photoprinted dot for a certain dot size in the negative can vary greatly depending upon the length of exposure, development, age of the photosensitive material, humidity, etc. All these factors should be controlled to provide a reproducible photoprinted dot size. In actual practice such control would be difficult to achieve. Essentially the same problem of controlling dot spread confronts the lithographer. However, procedures have been developed by L.T.F. for controlling photoprinting operations in lithographic plate making. In principle some of these procedures are applicable to other photoprinting operations, such as in photoengraving. Experiments carried out at Battelle Memorial Institute under the sponsorship of Photo-Engravers Research, Inc., have shown that the L.T.F. sensitivity guide can be successfully adapted to photoengraving.