A frisket is any material that protects areas of a work from unintended change.
On a sheet-fed letterpress printing machine, a frisket is a sheet of oiled paper that covers the space between the type or cuts (illustrations) and the edge of the paper that is to be printed. When the press operator uses a brayer to coat the surface of the type with ink, the ink brayer will often coat the furniture and slugs (wood and metal spacers) between the columns and around the type. To keep this ink from touching the target sheet, the frisket covers the area that is not desired to print. The frisket is set in a frame, often hinged to the tympan that holds the paper in place.
A new frisket has to be cut for each different page or form; a well-made frisket lasts for hundreds or thousands of impressions.
In airbrushing, a frisket is a plastic sheet with an adhesive backing used to mask off specific areas of an image so that only the exposed area is covered with paint. The frisket is vital to airbrushing, because it allows the artist to control excess paint spray, create special effects, achieve extreme precision, control edge attributes and to expedite the airbrushing process.
A frisket differs from other masks in that it is a single sheet that covers the entire work, parts of which are removed by cutting into the sheet. Friskets are available in matté and glossy finishes. Some friskets are also solvent-proof, manufactured for use with solvent-reduced and -based Urethanes.
The frisket is fixed to the painting surface and then the appropriate shapes are cut out of the material using a razor or scalpel. The cut piece is lifted, the exposed area painted, and the process repeated using the cut pieces to mask their matching finished areas. When all painting is finished, the resulting work contains precise shapes with no overspray.