by: Marvin Pook
Surface Cleaning of Paper
Surface cleaning is a technique that can be considered both maintenance and active conservation. Deciding what to remove and whether removal is necessary is the first step; understanding what is involved can help make the decision more straightforward.
Although it is not always necessary to remove all surface deposits from old papers, surface cleaning can improve the appearance of an object. Surface cleaning can also remove substances that might eventually cause damage through abrasion, transfer, acidity, or recurring mold growth.
Surface cleaning is a non-water or non-solvent based technique for removing surface deposits on paper-based materials. Surface cleaning can be an independent treatment, or a technique done prior to further treatments for example (mending, filling and missing parts) to prevent any deposits from becoming embedded in the paper fibres. Surface cleaning will not remove heavy soiling or staining that has become embedded in the paper such as water stains, mold staining, or mat burn.
Surface cleaning can be suitable for removing:
• accretions (sticky or waxy deposits that have built up on the surface)
• insect droppings
When and how to clean
The first step whenever surface cleaning is under consideration is to ask the question: Should the item be cleaned?
Asking this question involves considering a number of other questions:
• Will any historic evidence be removed in surface cleaning such as fingerprints or smudges on artwork?
• Is the item brittle, photographic, manuscript or a piece of fine art that can be damaged with even light cleaning?
• Do bound volumes need to be supported during surface cleaning with a cradle or foam book wedges to avoid stressing the binding?
If the answer to any of these questions is yes, cleaning should not proceed without assistance and/or consultation of a conservator.
However, if the paper items are stable, strong, and no evidential material will be removed or damaged during cleaning, the next step is to assess what sort of material you will be cleaning off and how best to remove it. To determine if any damage will result from cleaning, perform a low-impact test. Choose and clean a small area to see if there are any negative reactions: removal or smearing of inks, damage to the paper surface, or tears in the paper.
In addition, before you attempt the following procedures, practice them on expendable objects to test your comfort level with undertaking this treatment step and eventually working on an original object. If you are unsure of any of these techniques, be cautious and ask for help. With any object of value to your collection, a “First, do no harm” approach is best.
Once you’ve decided to begin, clear and prepare a fairly large work space. Place your manuscript, artefact or work of art on a large piece of cloth or paper, to help contain the dirt, for easy clean-up, as shown in the photo below.
After surface of the object was gently cleaned with a soft brush to remove loose dirt and dust. If soiling is heavy, brush debris into a HEPA vacuum with cheesecloth over the nozzle to catch any bits of paper that may come loose accidentally. Do not apply the vacuum hose directly onto the object. Brush both sides of the sheet. If the item is soiled with soot or mold.
To avoid enlarging tears, brush carefully in the direction of the tear from the inside out and not perpendicularly across it. Finally, any cleaning over stamps, seals, labels, and any other adhered pieces (like collage) should be undertaken with an especially light touch and extra care.
Because there are many erasing compounds many are also not suited to historic documents and works of art. Many of these products come in cloth bags that release small amounts of granules as they are rubbed across the surface of the paper, these granules are abrasive and can damage the paper fibres. Many are also chemically unstable and can lead to damage if they become embedded in the paper fibers during surface cleaning (granules) or leave behind residue (putty).
Suitable tools have specific qualities that make them safe:
• Brushes : For all surface cleaning procedures, a clean, soft, natural bristled brush is needed. A good rule is that a surface cleaning brush should be soft enough to use on your face or the back of your hand. Brushes intended for surface cleaning should not be used for wet work, and any brushes used on moldy materials should be thoroughly cleaned after use and not used for any other purpose.
• Vacuum: When soiling is heavy or might include mold, a brush can be used in combination with a high efficiency particulate air (HEPA) filtered vacuum. HEPA vacuums with variable speed air control are preferred to prevent high suction from damaging collection materials.
• Vinyl erasers: Grated vinyl eraser “crumbs,” such as from the non-colored Staedtler Mars Plastic Eraser, can be used for surface cleaning and are available from conservation suppliers in ground form. Grated vinyl erasers will not leave behind deposits when properly removed from the surface of the paper. Erasers should not be used in their block form due to their abrasiveness and the potential for over-cleaning.
Once the first step of brushing off any loose dirt or debris is complete (mold is not included in this step), consider the type of material you are trying to remove and select the best cleaner for that application. Most dirt-type coatings will simply need surface cleaning sponges or erasers; soot, for example, will require a surface cleaning sponge.
Small, localized deposits of dirt may be reduced by gentle rubbing with a surface cleaning sponge or a piece of a vinyl block eraser. When using the latter, cut the eraser into a wedge, pencil-point, or whatever will result in the best cleaning shape for this piece. Rub in short, random strokes to avoid creating a pattern of straight erased lines and be sure to check the surface of the paper periodically to be sure it is not being abraded.
Cleaning should always be done from the interior toward the outside to prevent catching the edge of the paper and tearing it, as well as to encourage detritus to move off the surface. When the sponge or eraser becomes dirty, trim off the soiled portion before you continue. If no soil comes off onto the sponge or eraser, do not continue: overworking one area can result in damage to the paper fibres and even tearing. When surface cleaning locally, be careful not to over-clean and cause the rest of the object to look dirtier in contrast. Try to avoid rubbing over media, whether printed or drawn, as this can remove original material and can potentially smudge some lower-quality printing inks. To help avoid these areas, barriers of polyester film (Melinex) or paper can be used. When cleaning around a tear for mending, a polyester guard can be put over one side of the tear to prevent any more damage to the already fragile fibres.
As noted in the “Cleaning Materials” section above, block erasers are not appropriate for cleaning larger expanses of paper, but grated vinyl erasers are. These eraser “crumbs” can be used on most printed surfaces; however, eraser granules should not be used in books as they become trapped in the gutter. To test the efficacy of the granules, pour a small amount on a small, unobtrusive spot and gently roll the granules in a circular motion with the fingertips (while wearing nitrile or vinyl gloves). If the cleaning is effective, the granules will rapidly become gray in color. Once you’re sure the granules are actually removing dirt, clean the rest of the surface in the same manner, brushing away the crumbs when they reach a dark gray color. When brushing crumbs, be sure to get any crumbs that may be below the item as well as those on the surface.
Soot can be deceptive and may initially appear to be dirt. If the surface dirt appears to smear or smudge rather than be picked up during cleaning, it is likely that the soiling is soot.
Soot should be removed with a surface cleaning sponge using a straight up-and-down motion (no horizontal, side-to-side rubbing) working across a document. The sponge is designed to pick up the soot and hold onto it and thus prevent smearing. Just as when you’re removing dirt, trim off the soiled portion of the sponge as it becomes dirty and continue with the cleaning process until the sponge does not pick up any more soot.
Surface cleaning can benefit books, documents, and works of art by improving their appearance and preventing the damage that dirt, dust, soot, adhesives, and accretions can continue to cause. As with any new skill, practice and repetition will improve results. It is best to practice on non-collection items to become comfortable with the techniques prior to surface cleaning any items in the collection. As with anything that involves the actual treatment of an object, consult with a professional conservator if you have any questions.