Caring for Prints ...

Discussion: Removing Spots from Prints

Editor's note: The comments you are about to read have all been 'clipped' from a discussion on this topic that took place on the University of Kansas 'PrintsL' mailing list in March of 1998. I have deliberately refrained from crediting the writers of each posting - the discussion was quite far-ranging and extensive, and clippings taken out of context as these are do not fairly represent each author's complete views on this complicated and provocative subject. It is thus better that they remain anonymous. But thank you - ladies and gentlemen - for sharing your knowledge and experience.

Information on the 'PrintsL' list and how to access their archives, where the complete discussions can be found (properly credited to their authors), is at:

Q: I have used a weak solution of Clorox to remove the foxing on inexpensive old colored lithos with good success and no noticeable effect on the colors. Before I try it on a small dry point, is there any reason why it should work differently? Is there a better way?

Response: PLEASE don't bleach prints with chlorox. Yes, it works, but later the paper will suffer. There are ways to neutralize the chlorox, but some of these chemicals have their own serious problems, too.

Light bleaching (that is, with near-UV light) in an alkaline solution gives excellent results and is relatively safe, though it should NEVER be done on a paper containing lignin.

Response: The best method that I know of to remove foxing is immersion in a solution of plain tap water (not distilled water) and a chemical called Chloramine-T. It comes in a powder, and can be ordered in 1, 5 or 20 pound bags from a company called Talus in New York. It's better than hypochloride (bleach) because, in theory, it clears in the fresh water rinse. Orders for another chemical, hydrogen peroxide (high concentration, powdered form), are apparently outstripping orders for Chloramine-T at a ratio of 5 to 1 (according to the owner of Talus). Regardless of what the conservators are doing behind closed doors, DON'T use peroxide unless you have bacterial problems that must be addressed. Bleach uncleared does its damage over time; peroxide in high concentrations does its damage immediately, even if it can't be seen.

Chloramine takes a long while to work, but it is an effective cleaner and defoxer, and should render the need for bleach unnecessary.

Response: It is a well known fact among conservation professionals that bleaching is ALWAYS HARMFUL to any piece of paper. No matter what method is used the cellulose will be attacked by the bleach. Bleaching will change cellulose molecules so they do no longer reflect light in another frequency (towards the red end of the spectrum: brown discolourations) so the cellulose looks white again. In doing so the molecule is changed -damaged- by the bleaching agent.

In the 60's people believed chloramine could be rinsed away, now we know this is not the case at all!

Response: The most recent offering here (UK) as a 'safe' cleaner combines Hydrogen Peroxide and Ammonia (5:1), used very dilute. Again the theory is that all of it ends up as gas and vanishes leaving no residue. I have scribbled formulae on paper and tried to work out why the magic 5:1 ratio, but am none the wiser. Surely any form of cleaning, save removing surface soiling, must result in paper and image degradation, and there must be a trade-off between these irreversible changes and the enhancement of the image (hopefully back to its original glory) gained.

Response: I hear on the street that calcium hypochlorite has largely replaced Chloramine-T (rinses away much more completely, I'm told).

Response: Tests have shown Chloromine-T does NOT rinse out of cellulose, contrary to the initial description of this bleaching agent. The advice is: discoloration products may be able to be washed away safely by a bath in water, with a slight amount of alkalinity added, but chemical bleaches are not safe.

Response: The use of light or UV in combination with moisture is said to be the least damaging treatment. According to the work of the late (and lamented) Keiko Mizushima Keyes, this technic is best for Japanese woodblock prints and other prints. See a brief article in "The Paper Conservator" (Journal of the Institute of Paper Conservation) 3:1-8, 1978.

She described the method in greater detail in another paper: Schaeffer, T.T., Blyth-Hill, V and Druzik, J.R. The Paper Conservator 21:1-14, 1997 "Aqueous light bleaching of modern rag paper: an effective tool for stain removal" (a well documented study with color pictures). Essentially, one immerses the work on paper in water and puts it in the sun. That's all. Others, lacking noon day sun use UV, I've heard. It may be slow but it does not destroy paper. As a footnote, I have seen prints that were "cleaned" with Chloramine-T that are 35 years post-treatment and washing without fading of vegetable dye colors or return of foxing. Several issues of the referenced publication contain additional contributions on this subject by conservators and paper scientists.

Response: Exposure to UV might not destroy the paper immediately, but if there are impurities in the paper, it will promote oxidation which breaks down the chemical bonds that hold cellulose (paper) together. Peroxide does the same thing. Oxidation of the impurities in paper will become visible as discoloration, the color depending on the source of the impurity. Using tap water compounds the problem as it adds more impurities to those that may already be present in the paper. Prints that are displayed should be protected from UV exposure with UV-blocking glass or plexi, and as even the UV emitted by fluorescent lights can be harmful, these lights should be fitted with UV-blocking sleeves.

Response: I don't think that anyone has mentioned the great danger of immersing water-based inks in water. Anyone reading the comments so far might blithely assume that any print, including, say a Japanese woodcut from the 19th century, can safely be washed this way, when in fact this is not the case.

Response: Naturally, one would not want to put prints with water soluble inks in water, however, since most print artists aimed for some degree of permanence, I imagine that water-fast dyes/inks are more common. Japanese woodblock prints of the 18th C. with violet or purple colors will run in water because both the red and the blue colors used to obtain violet are partially water soluble. And in 19th C. prints, aniline reds and violets smear like crazy. Beware.

Response: UV and bright sun will fade the organic dyes used in woodblock prints and such prints must never be hung on walls or otherwise exposed to bright sunlight, dry or wet. As the article cited, the light moisture technic was used on stained 'modern rag paper'. I regret that my mention of Keiko Mizushima Keyes in connection with Japanese woodblock prints indicated that this method was routinely used to clean them. As a paper conservator, Keiko worked with rag papers also.

Response: Well, it's better not to use tap water for rinsing prints, because it often contains iron, etc., even if it has not been chlorinated. Distilled or de-ionized water is usually used, and if the latter, it should be supplemented with added calcium. Nothing's simple...


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General comments

It is often judged best, by conservators and curators both, to leave a print alone rather than to treat it for a purely cosmetic purpose. I think one decision that comes into play is: does the print require any sort of treatment in order to be stabilized? In the case of foxing, as I understand it, as long as the work is kept in a responsible environment (low light, low humidity), foxing will be arrested (not reversed, but it won't get worse).

I will often elect to simply house a print that might normally be perceived as needing washing (lignin content paper that has yellowed or become brittle, for example) in a folder made of a good buffered, Ph-neutral or slightly alkaline paper, such as "permalife" - or I may use this sort of paper as a cover sheet if the print is matted, instead of glassine. It is my understanding that this will slowly (decades) leach some of the evil spirits out the paper and help to preserve it. In any event, a course of no or very mild action is often the best path. If a work is in peril without treatment (it will degrade without treatment) then treatment may be warranted (removal of pressure-sensitive tape comes to mind). I like to think that better solutions to these problems may be developed in the future and if I have stabilized a print rather than treating it prematurely then it might still be treated by better methods in the future.

The manufacture of the paper is one variable. Not all papers are created equal. One example of this is that they do not wet out and then dry in the same manner. Not surprisingly, some are trickier than others. You may effectively eradicate the foxing using an aqueous technique but end up with one very wrinkled and distorted support, because traditional 'flattening' techniques have failed. What happened? Did the sizing wash out? Does it have to do with the grain direction of the paper? Did the manner in which the media was applied have some effect? This aspect is particularly critical when it comes to preserving a platemark. Overzealous efforts to rid that paper of persistent wrinkles or undulations to get that paper nice and flat may be done at the risk of losing one of the most essential elements of the print itself: the platemark!

Media is another huge variable. Some colorants whether printed or applied by hand are going to be sensitive to any number of aqueous treatments, including those that range in alkalinity. Although spot testing will identify the limitations of the media in most cases, time may not always be taken to gather that information on those items that don't warrant the care and procedure of a conservation treatment. I won't labor the potential for disastrous outcome.

The nature of the damage to a print is also a factor. Foxing may have developed as a result of too humid conditions which in turn may contribute to other forms of degradation that will affect what kind of conservation treatment a print ultimately should or should not receive. With all due respect, these other factors are not always apparent to a non-conservator as a spot of foxing may be. Also, a paper support damaged by years of poor storage and handling may not be able to withstand even a relatively mild conservation treatment. Obviously, heroic efforts will have little effect.

There is also the question of working space and conditions. Even basic treatments have a certain criteria that should be honored. A work space should be ample, clean and reasonably environmentally stable. Often the space allotted is too damp, dirty or an area shared with lunch breaks.

For these reasons, I believe that it simply is not possible or responsible to hand out a 1-2-3 approach.

Final comment: They'll all rot eventually no matter what we do...(prints, purveyors and purchasers), so enjoy things while you can!