Printing Large Areas of A Single Color

Many times a job with a large area of a single color must be run with more ink applied to the rollers in order to maintain a solid, consistent color across these large areas. The extra ink helps the dark areas, but it also causes some problems. Halftones suffer as dot gain becomes more pronounced, fine lines may thicken slightly, and thicker ink takes longer to dry and risks offsetting on the next sheet as it comes out of the press. These problems can be avoided by using a second plate of the same color to strengthen the density of the solid areas. If you decide the run with one of the techniques discussed here, please call our pre-press department at 503-231-8328 before setting up your files so we can give you individual instructions.

Running an additional plate to strengthen the solid areas of ink is known as double-bumping. Separations for this technique are generated in design programs by making a copy of the large objects directly underneath the original ones and overprinting the originals. You would typically fill the underlying objects with 30-80% of a double-bump color and run both the original color and the double-bump color in the same ink from two units on the press. A double-bump plate is not simply a copy of the plate which needs strengthening. All solid areas should be run with a 30-80% halftone in the double bump areas, and all objects which do not require the double-bump should be left off.

If you are printing a black + 1 spot color job with large areas of black, you may set your double-bump objects in the spot color and overprint the black. This will increase the black density without having to introduce a second black plate. In some instances, this technique may also be suitable for a job run with one dark spot color and one light spot color.

If you are printing a process job with a large area of black, ie. a full-color poster with a few pictures on a black background, you will likely want to run the black areas as rich black. Instead of using only the black ink on the large objects, make them 40% cyan, 30% magenta, 30% yellow, and 100% black. This will keep the black areas very dark while still allowing us to run the black ink at a reasonable density.