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Flat Sheet Lithography
Flat Sheet Lithography offers the highest quality
for envelope printing. It produces a clear,
well-definedimage area and provides excellent
ink coverage. It is effective on many different
paper surfaces from smooth vellums through
laids, opaques and coated sheets to embossed
finishes and heavily textured felts. Flat Sheet Lithography (FSL) or Offset printing is done before the envelope is folded and allows for heavy coverage, bleeds into windows, and bleeds off the envelope.
The lithographic process is based on the principal that oil and water do not mix. The surface of the plate is treated so that the non-print areas attract water and the printing areas repel it. If the plate is dampened before the ink is applied, the non-print areas absorb the water and the oil-based inks will only be attracted to the printing surfaces. The dampening rollers pick up water from the reservoir and apply it to the surface of the plate. A series of ink rollers pick up, meter, and apply ink to the plate. As the plate turns against the blanket cylinder, the ink is transformed from the plate to the blanket. The blanket cylinder controls the pressure and allows a perfect “kiss” onto the substrate to insure the highest quality.
Offset printing can accurately apply a light coating of ink so it can be used with a very fine screen. Screens with 150 to 175 lines and higher are normally used with wet offset in the envelope industry, but wet offset can be used with screens as fine as 300 lines. Our services enable us to quickly and cost effectively provide you with FSL jobs up to 8 colors plus an aqueous coating. Please call, fax or email us on your next opportunity.
