A technical dictionary of printmaking, André Béguin.
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Conservation of prints
Prints are fragile objects due to the material they are printed on (usually paper) and the black and coloured inks used. The paper used to print on is sensitive to humidity as well as to excessive dryness. This paper should usually be kept at a 5% humidity content. Furthermore, it is also very sensitive to temperature changes (especially if they are rapid), to light, to being handled, and, of course, to all kinds of wear and tear.
Once printed the impression (inked paper) is particularly sensitive to light but also to rubbing. Prints are best kept in a place where the temperature is more or less constant (18° to 20° Centigrade - 64° to 68° Fahrenheit) and where the humidity is normal.
Generally speaking it is best that prints be kept in folders* rather than being framed, especially if they are colour prints. Sunlight, and even moonlight, yellow the paper and, in the long run, will alter the tones of a print. However, if one is careful to frame a print so that it is quite air tight and then make sure that it is not in direct sunlight it will be found that the damage will he diminished considerably. If one owns many prints it is a good idea to rotate them so as to minimize their exposure. Artificial light does not make paper turn yellow but make sure that the lamps used do not diffuse too much heat onto the prints near them. There are special lights used in display cases which do not heat up and which may be used.
The paper that is least sensitive to light is the beautiful rag paper which has not been whitened artificially or which has an off-white colour. Paper that is kept in full sun light may turn yellow in a few weeks [* paper].
In the end of it all prints which are kept in a folder are the best protected unless, of course, they are available to the public to be thumbed through. Prints should, in fact, be kept in a plastic cover or, as used to be done, under two layers of oak tag one of which is cut open to the size of the printed image. A further precaution, especially for fresh prints, consists in interleafing each print with a dry sheet of good quality tissue paper. An old sheet of tissue paper may damage the prints. Interleafing protects the relief parts of a print which are particularly sensitive to rubbing.
The best type of folders to keep prints in are those that can be closed up so that the dust will not penetrate. Many museums or print departments keep their materials in folders which are lain horizontally for best results. In the orient, on the other hand, prints are kept in closed wooden boxes.
Insofar as frames are concerned they should be hermetically closed and clips should not be used for anything but short exhibitions. One might choose to use plastic materials such as plexiglass or similar materials rather than glass since the former are both light and unbreakable. However, if plastic is used make sure that the room is not too hot and dry since this might make it bend out of shape. Furthermore, it may be pointed out that plastic is much more easily scratched than glass.
One may also use special "glare-free" glass which will eliminate the glare in the rooms that have a lot of light but its opaqueness is such that the print will be somewhat less visible.
There is another fairly inexpensive way of framing prints which may be used for short exhibits or even for transporting fragile prints. The print can be placed on a wood or plywood backing which must be one centimeter thick (about half an inch) and must be quite flat. The print and the backing can then be covered with a plastic sheet such as "rhodialine" which can be bought by the yard. These sheets may be bought in two different thicknesses of which the thinner is best since the thicker one is hard to stretch properly. The stretching of such sheets is done by pulling them and fixing them to the back of the wooden board with staples.
Of course a better kind of frame is the traditional one which may be made to size or bought in different sizes. Generally speaking these frames have either silver coloured or golden coloured metallic borders. Such frames work even better if one places a passe-partout border between the print and the frame so that the surface of the print will not come into contact with the glass cover.
Varnish should never be used except in silkscreen work.
Prints should be taken out of their frame if they begin to buckle or show signs of change (foxing, spots, etc.) A framing which shows signs of condensing on the inside of the glass or in which the ink comes off on the glass surface is no good. The glass surface does not, however, damage a print by mere contact unless the relief of the print is quite pronounced.
Insofar as the transportation of prints is concerned it is always best to put a print between two pieces of thick cardboard and attach the cardboard sheets to each other in such a way that the print cannot move and be rubbed between them. This can be done by adding some tissue paper.
If a print is to be sent by mail it can he rolled up and sent in a tube as long as the tube is made of hard cardboard and can be closed on both sides. The diameter of the tube should be fairly big (16 to 15cm - 4 to 6 inches). If the print to be sent is a large one it is often best to roll it onto the tube itself and then proceed to protect it as well as possible on the outside.
Engravings, lithographies, silkscreen prints, etc. must be kept the way they were when printed and thus the borders must be neither cut nor damaged. If one wishes to fix a print onto a cardboard backing of a frame this must never be done with scotch tape, glue or similar means. Prints can be mounted very simply by making a kind of photocorner with paper (the corners of envelops will do) and gluing these to the cardboard backing in order to hold the print.
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