Dry trapping is also more expensive because the paper travels through the press more than once. This is done by moving the web of paper around a series of heated iron drums in the dry end of the paper machine. This printing process allows the use of extremely fine line screens to produce high resolution printing. A dummy is made of the same paper stocks that will be used in the finished piece and serves as a reference for the client, designer, printer, mailing house, or distributor. The printer, paper merchant, or paper consultant generally provides the dummy at the request of the designer.
Most halftones are one color, printed with black ink on white paper.
By blending the black of the tiny ink dots and the white of the paper, the human eye sees shades of gray. Duotones are made by printing an image with two colors, generally black and a second color. The full range of tones are printed black and the middle range of tones are printed in the second color. The result is a striking image with more richness and depth than a one-color halftone. The cost of printing tritones or quadratones may be as high as or higher than four-color process printing.