About Conservation

Paper can be bathed in modified water (aqueously treated) to chemically stabilize it by raising its pH from acidic to alkaline. Increasing paper pH to neutral or slightly alkaline helps to increase its longevity. Aqueous treatment also benefits paper fiber strength.

Bleaching paper has some inherent risk. Bleaching paper to improve its aesthetic appearance often does not produce permanent results. Color reversion, or the reappearance of stains, is possible over time. Bleaches that produce the strongest whitening effect weaken paper fibers. It simply is not advisable to bleach to the point of pristine whiteness if the integrity of the paper is compromised as a result. The conservator and the client should discuss the balance between acceptable levels of paper lightening versus the possible weakening of the paper fibers so that together they can have a realistic understanding of the improvement to risk ratio.

The inks used for etchings and engravings are usually very stable. Usually, these artworks need conservation treatment not because of media problems, but because the paper is not chemically stable, or is physically damaged, such as tears at the platemark.

Because the media is usually stable, water-based (aqueous) conservation treatment for the paper is possible. This enables the conservator to wash the print to reduce paper degradation products which cause yellowing. Removing paper stains, foxing, and mat burn by bleaching the paper is also a feasible treatment option. Read about washing and bleaching paper above for more information.

Iron gall ink corrosion is the most common problem addressed during the conservation treatment of most older manuscripts. The ink is inherently acidic and causes the paper beneath it to rapidly degrade. Eventually, the ink “eats” straight through the paper, leaving a loss where there once was a word. The problem is made even more complex because the manufacture of iron gall ink was not standardized. Iron gall ink was made in every household, using hundreds of different recipes. Each recipe, however, did have one thing in common; vitriol (iron sulfate), which is the cause of the acidic ink problem. Iron sulfate is highly acidic, especially in the presence of water with which it forms sulfuric acid. Iron sulfate also forms free radicals, iron (II) ions, which increase the rate of oxidative breakdown of paper. Iron gall ink corrosion can be stabilized chemically and physically.

When considering how to provide conservation treatment for a painting on paper, the conservator needs to consider how the media will react to treatment in addition to how the paper will react. What may be appropriate for one may be inappropriate for the other. For some paintings, aqueous treatment is not possible, but solvent treatment and dry cleaning can be performed to lift off surface dirt and reduce staining.

Finding a treatment that is beneficial to both media and paper requires testing. There is not a standard protocol for each media type. One watercolor, for example, may react very differently than another. The goal is to test each color of the painting until the conservator discovers a water to solvent ratio which, ideally, allows the paper to be treated aqueously while not causing the media to run. Depending upon the media solubility parameters, “wet” treatments could be performed in a bath, on blotter, with gels, or on a suction table.

Once the paper has been chemically stabilized, it can be mended to assure its physical stability as well. Cracks and losses in the paper can be infilled with alphacellulose paper fiber, or mended with 100% kozo Japanese paper.

Paintings serve a primarily aesthetic function, so whenever possible, losses to the media should be infilled to re-establish the artwork’s primary function. The conservator must repair the media in a manner which is sympathetic to the original, but does not try to falsify it. Generally, this means that the conservator applies a release layer underneath the newly applied media and that the new media is applied in a tiny dot pattern so that it is easy to distinguish it from the original but from a near distance, disappears into the painting.

Book conservation treatment is often complex, and it can be time consuming and expensive. Unless the book has sentimental value, it is best to know the market value of your artifact, and to invest up to that amount in its conservation treatment. Frequently, protective enclosure, not full conservation treatment, is the most cost-effective solution. Museum collections and sentimental collections of books are the exception. Their value cannot be measured with monetary considerations alone.