Technical Leaflet from the Northeast Document Conservation Center
When to Clean
Although it is neither necessary nor desirable to remove all dirt or discoloration from old papers, some cleaning will often improve the appearance of an artifact. Cleaning can also remove substances that could eventually be detrimental to the paper.
The term “cleaning” refers to a variety of conservation procedures. The simplest of these is surface or “dry” cleaning, which is done with a soft brush or an erasing compound. If the dirt is superficial, a dry surface treatment may provide ail the cleaning that is necessary. Paper may also be cleaned with water. Placing an artifact in a bath is the most common way of cleaning with water, but there are other aqueous methods that do not require immersion. The most complex cleaning procedures involve chemicals. The two principal types use bleaching agents or organic solvents. These methods, especially bleaching, are most appropriate when the appearance of the object is of great importance. Surface or dry cleaning can be safely carried out by a novice. If more thorough cleaning is required, it should be done only by a conservator. Surface cleaning should precede wet cleaning and mending. If documents are not dry cleaned before washing, surface dirt may become ingrained in the paper. Adhesives used in mending can also set surface dirt in place.
The surface cleaning technique described here may be used on book pages, manuscripts, maps and other documents. It should not be used on brittle newspapers, bookbindings, book edges, photographs, or intaglio prints (those with raised lines such as engravings, etchings, etc.). Neither should it be used on pastels, pencil, charcoal, watercolors, or other media that are not firmly bound to the paper or that may be lifted or erased by abrasives. Objects with hand coloring should not be treated because coloring may smear, especially if hand applied. Cleaning all such objects should be left to a professional conservator.
Supplies and Equipment
Materials needed for dry cleaning are a soft brush (a drafting brush is excellent) and an erasing compound. Different types and commercial brands of erasing compounds are available. These vary in composition and are sold as granules and also as block erasers. Most granules are potentially damaging to paper if not properly removed after cleaning. Some have the additional problem of being too abrasive. Based on current information, granules sold under the name Skum-X Powder (TM) are the most easily removed and the least abrasive. These granules are sold loose in canisters. At present it appears that all cleaning granules sold in dry cleaning pads contain a different type of erasing compound and should be avoided. Block erasers may also leave a damaging residue, so care should be taken to remove all traces of this erasing compound as well. Non-colored vinyl block erasers, such as the Magic Rub Eraser and the Staedtler Mars Plastic Eraser, have the least potential for damage to paper.
How to Clean
To start work, clear an area that has a large, clean, smooth surface. Begin the cleaning by brushing the surface of the object with a soft brush to remove loose dirt and dust. Use up-and- down strokes and work across the paper. Be careful to avoid enlarging tears by working towards the tears and in the direction of the tear. With books, be sure to brush the dirt out of the gutter.
If, as is usually the case, dirt is well attached to the paper, an erasing compound is more effective than a brush. But use a brush first to remove the loose dirt. Because residues of the erasing compound may be left behind on the paper regardless of how carefully the paper is brushed after cleaning to remove them, an erasing compound should be used only when necessary. If the erasing compound does not appear to be removing dirt, do not use it.
Test first in an inconspicuous spot to make certain that no damage to the media will occur. Steady the paper with one hand and test by gently rubbing the granules with a finger over one small area. Once you are certain that the media will not be lifted or erased, begin cleaning. Sprinkle granules from a canister over the object to be cleaned. Using your fingers, gently rub the granules over the surface of the object moving in small circles to avoid streaking. Start from the middle and work towards the edges. When cleaning near the edges, do not use a circular motion, but rub from the middle towards the edges using a straight movement. This will prevent tearing the edges, which are often fragile. Be careful going over inks that have eaten through or weakened the paper. Avoid areas of color or pencil notations, which may be archivally significant.
Granules and loosened dirt produced during the cleaning process should be brushed away frequently. Keep a careful eye on your work at all times to make sure that you are not smearing the medium or producing any tears and that you are not erasing or lifting anything but surface dirt. If the granules appear to have a color other than that of dirt, check to make sure that ink or color is not being lifted from the document.
It is essential that all granules be removed from the object following cleaning. Brush both sides of the object thoroughly and give special attention to the gutters of books, where granules may accumulate. Remove treated objects from the work area. It is most important to keep the work area free of the erasing granules produced by cleaning. If granules remain on the working surface and the paper to be cleaned is placed over them and rubbed, holes may be created in the paper. Working on large sheets of brown kraft paper may help you dispose of the granules.
While granules will remove most surface dirt, block erasers may remove even more. It is not necessary or even desirable, to remove all surface dirt from old documents. Erasers can abrade soft papers and are best used by persons experienced in surface cleaning. If it is necessary to use an abrasive harsher than granules, a block eraser is comparatively safe. Proceed with caution, trying an inconspicuous spot first. Rub gently in a single direction or in small circles. Take care not to create light erased areas, which will contrast with the general surface color. Do not use erasers over pencil, color, or inks.