The American Institute for Conservation

Pasteboards

Book conservators are generally familiar with producing their own boards for use in conservation-quality rebinding. Laminating quality matboard has been a common method of producing boards of better composition than commercially available boards. However, these boards lack the weight, "feel", and desirable working characteristics that are associated with traditional pasteboards. The following procedure, using a combination of common materials, was developed to easily produce boards of known quality that duplicate the weight, workability, and "feel" of traditional pasteboards.

Materials

Whatman #1 Chromatography Paper - This paper is used as the outer surface of the pasteboard, and provides a clean workable surface. Any fine quality waterleaf sheet of paper could probably be substituted.

Cotton Linters - Cotton linters form the core of the pasteboard. It is easily available, fairly inexpensive, and seems to yield a very flat board when dried. It is possible to substitute blotter, but blotter often yields boards that are warped and must be flattened after the initial drying. I have also tried Abaca linters, which produced a rougher surfaced board that was very tough and solid.

Flour Paste - Unbleached wheat flour was cooked, four parts water to one part flour, until thickened and tacky. The paste should be strained before use and mixed with enough water to reach a heavy cream consistency. Standard wheat-starch paste can be substituted if desired, but it is possible that the gluten and other proteins in flour may yield a harder, less flexible, board.

Equipment

• A tray large enough to dip the linter sheets.
• Reemay/Hollytex sheets.
• Waste blotter.
• Press and pressboards - A hydraulic paper-maker's press is excellent, but standard presses work well. The pressboards will get wet, so it is probably wise to line wood boards with polyester film or polyethylene sheeting.

Procedure

1. Determine the number of layers of linters required to be thicker than the desired result, as pressing will compact the stack beyond the initial dry thickness. Cut cotton linters somewhat larger than the desired final size. Cut two sheets of Whatman somewhat larger than the linter size.
2. Mist the Whatman sheets lightly with water to avoid wrinkles. Place one sheet on a piece of Reemay over waste blotter on a pressboard.
3. Dip a sheet of linter into the paste mixture. The best result is a thin but even layer of paste on the front and back of the sheet. It will be necessary to adjust the amount of paste and water to achieve the desired result. Also, paste and water will have to be added throughout the process to maintain the correct mixture. Layer the desired number of linter sheets onto the Whatman sheet. Top the stack with the second Whatman sheet, Reemay, waste blotter, and a pressboard.
4. Transfer the stack to the press and begin pressing. Increase the pressure slowly to avoid excessive squish-out of paste. The goal of this step is to remove as much water as possible while leaving the paste. The stack can be left in for several minutes, adding pressure as needed.
5. Remove the damp pasteboards from the press. Larger sheets should be dried flat on drying racks. Smaller sheets can be dried upright leaning against a wall or each other to allow even drying all around.
6. If sheets should dry warped, they can be humidified briefly and pressed between dry blotters. A faster method of flattening is possible if a dry-mount press is available. Humidify the boards until they are slightly flexible and put in the dry-mount press at low heat for several minutes. Remove the pasteboard and let cool under weight.

Suppliers

Linters - Lee S. McDonald, Inc. P.O. Box 264, Charlestown, MA 02129 (617) 242-2505.

Whatman #1 Chromatography Paper - Any scientific supply company, such as Aldrich.