The Basic Process of Letterpress Printing
Traditionally, letterpress has been done with mostly steel, lead or carved wooden type, along with hand etched pictures, pressed into paper. Letterpress has been used for centuries to widely distribute printed material, and over the last decade has created a demand in fine stationery and wedding invitations. Letterpress struggled with the invention of offset printing (flat printing). Offset decreased the demand on this antique art, because it is much less labor intensive - reducing the overall cost. However, the tactile charisma that letterpress offers, in such a widely digital world, has spurred on a new wave of letterpress lovers.
Nowadays, most letterpress companies combine the ancient art with a relatively new technique that includes printing with photopolymer plates. These plates begin as a digital design, broken up into each color, and flat printed onto a transparency. This transparency will allow photopolymer film to be exposed through it, creating a raised surface. Once cleaned, it is attached to a plate (usually either steel or acrylic). This is the "photopolymer plate" that will be used to press into the soft paper later in the process.
Next comes the most difficult part of the process, preparing the press to print. Every design has a different impression, and therefore will print differently. The depth of the impression will vary, as will the ink coverage. So, the operator must perform his "make-ready." Every operator has a different process of make-ready, so here is one that might be used:
Make-ready begins with inking the machine up with a thin layer of ink, removing all previous make-ready, and taping a transparency where the paper will eventually go. Then the operator will print on to the transparency, to determine exactly where to place the paper, for the proper "registration" (alignment).
Once the registration is set properly, the operator will likely move to adjust the printing depth. This requires the operator to raise or lower certain areas of the printed region, to allow for a deeper or shallower impression in a specific area, so that it will be consistent throughout the piece. Usually this will also allow the inking to be even, but when it isn't, he might have to add or remove tape from the rails that the ink rollers pass along, raising or lowering the ink rollers.
Once finished with the make-ready process, it is time to start printing. Some machines need the operator to hand feed each sheet of paper that is to be printed, while others are calibrated to automatically feed each sheet. All of the paper being used must be cut to exact dimensions to keep everything aligned properly.
After printing is finished, the operator will clean the press down, removing all ink, and oil the entire press. If there is an additional color, the full process starts over, allowing extra care to be taken to properly align multiple colors.
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