Caring and restoring prints
From the moment they are created, prints will start deteriorating if not properly stored or handled. They are very fragile objects due to the material they are printed on and also very sentisive to temperature changes, light and moisture.
Even when using papers of the highest archival quality (less subject to alteration than papers composed of cellulose fibers from plants), humidity and excessive dryness may put the print in jeopardy. This is because paper is a hygroscopic material (moisture absorbing), so it will absorb all the moisture found in the air and micro-organisms will attack the size and encourage the formation of mold. Foxing (rusty brown spots caused by micro organisms which form iron impurities in the paper) and mildew, are the most common problems which any collector should learn to recognize in order to assure the proper care and safety of prints; examination of the work and diagnosis of the "health" of a print should be undertaken regularly.
Another concern is discoloration of the print, which could be caused by dirt, dampness or by the breakdown of cellulose fibers.
Once the problem has been diagnosed, it is essential to find a specific treatment for the print. It is important to remember that restoration is a specialized science and if not done properly, it can damage the print forever. You should contact conservators when handling important historical prints.
HOW to take care of your PRINTS
- A good picture frame not only complements your print but it will also protect it. Acid-free mats are used to prevent the glass from touching the surface of the print and these must be of archival quality.
- Do not hang prints over radiators or air vents as heat changes can affect the print and can be responsible for the warping of the paper.
- Avoid direct sunlight; prolonged exposure will cause the print to fade and the paper will yellow.
- Prints should be hung with a slight forward tilt to leave space for air to circulate behind it.
Alterations due to light damage
Exposure to direct sunlight causes yellowing of the print and damage to the tones.
Yellowing is a natural oxidation of an old print. However, if not exposed to sunlight, prints will not become excessively yellow.
When prints are framed in poor quality mats made of ground wood pulp, the effect of the chemicals leeching out from the core of the mat board through the cut in the window mat will cause brown stains that follow the contours of the window in the mat. The effects may be more severe within the window area because this area is also exposed to light. Furthermore, when the glass protecting the print presents irregularities such as spots or marks which cast small shadows, lighter areas or spots will appear where light has not oxidated the paper.
The progressive yellowing of a print can be slowed down by a kind of bleaching of the sheet of paper. This is a very delicate operation which requires immersing the print in a solution. Such a "bath" is only possible if both the paper and the ink take well to it.
Such baths are usually given to engravings and lithographies printed with oil based inks and that have not been coloured with water based colours. The print must first be immersed in clean, cold water so as to wet and wash the paper. The print is then placed between two white blotting papers and a second or "bleaching" bath is given.
Damage due to humidity
The damage done by humidity is one of the most ruinous for prints not only because it favours the growth of bacteria but also because it will make the paper buckle, dissolve the sizing, destroy the assembled pieces (glued backings, etc.) and provoke the formation of spots and water marks.
In damp conditions prints can easily become affected with mildew, a superficial coating or discoloring of paper caused by fungi. The mildew feeds chiefly on the size in the paper and by the time the discoloration produced by the dead fungus has been removed the size has practically disappeared too, leaving the paper, to all intents and purposes, as soft and absorbent as blotting-paper.
A really good, strong fibred paper will stand this, but a poor fibre relying upon the size for its strength would naturally go to pieces at once. Though the absence of size may make other papers less liable to the growth of mildew, the moisture they will contain will aid its germination. It is not uncommon for a collector to notice mildew (recently started) and to find out soon that the marks have disappeared when the print has been exposed to dry air for a short time. Sunlight and even the dryness of a living room will often check the continuance of growth, but the mildew is not dead. It is still in the paper, and will renew its activities at once if favourable conditions are restored.
To kill the spores, chemical treatment is essential. Even paper upon which there are no signs of active mildew is better treted if there is reason to suspect contamination. There is no need to place a print in formalin bath. A sponge or large brush applied to the back is all that is necessary.
If a print has undergone excessive humidity, the spots are not easy to remove. The print can be washed either partially or totally, depending on the size and amount of the spots. The spots can be treated by dabbing them slightly with a cotton tip or a brush dipped in bleaching solution.
Any wrinkling can be lessened by dampening the paper and then drying it under pressure.
Any gluing, backing up and framing should be done only after the print has dried properly.
Damage due to excessive heat
The destructive effects of heat are often closely associated to excessive dryness and to excessive humidity. When heat is very dry, paper becomes very brittle and friable and the coloured areas as well as the inks become scaly.
When heat is very damp, various kinds of plant life may begin to develop.
If the temperature rises excessively, the "burned" paper turns reddish or leaves a well known brownish border area.
Not all papers can be regenerated after suffering from excessive heat. To regain a certain suppleness, a print should be placed in damp (but not excessively damp) air. However, when paper becomes brittle, it must be reinforced by a backing-up sheet of paper.
The areas of the paper that have turned reddish should be removed being careful not to cause rips and the missing pieces should be replaced with cut outs. Only in some cases, can bleachings be undertaken.
Damage due to the hyper acidity of paper
If a paper is excessively acid it will lose its colour after a certain amount of time. It will also grow darker and will end up by destroying itself as the fibrous structure will slowly be annihilated.
The hyper acidity of paper can be measured with a pH meter or with pH papers which turn colour when put into contact with a wet surface.
This problem can easily be remedied by washing the paper and by applying some alcaline solutions.
Damage caused by biological agents
The mushrooms and bacteria that live on paper develop in a damp and hot atmosphere, especially if the prints are poorly aired or if they are kept tightly packed in groups. The softest papers are the most vulnerable ones. Biological alterations usually manifest themselves in the form of yellow spots but they may also be brown, blue, or black. At times a slight white growth can be seen on the paper surface. The parasites that cause this kind of damage can only be removed by disinfecting the paper.
There are various ways of disinfecting paper:
- Gas or vapour emanation carried out in a hermetically sealed box.
- Evaporation of a liquid fungicide.
- Two sheets of tissue paper are impregnated with the fungicide and then put above and below the print to be disinfected.
- Vaporisation of a disinfectant.
One of the most often used products for this kind of work is "Thymol" in crystal form which is applied by emanation.
| The Care of Prints and Drawings (American Association for State and Local History Book Series)
by Margaret Holben Ellis
How to clean the surface of prints
Prints that have been exposed to smoke and dust are often dirty and gray. Cleaning always begins with a dry method using compressed bread crumbs which absorb dust very well. After both sides of the paper have been cleaned, the crumbs are then brushed off.
Erasing is sometimes done with draft cleaning powder (available in pads or loose in tubes) or with a soft eraser limiting its use to outer areas of the print, as finer lines of the print can be affected. The eraser is usually cut in such a way that small areas can be reached. Hard, abrasive erasers must be avoided or used very carefully only on certain spots and on well sized paper. To remove the dirt-collecting particles left by the cleaning powder, use a soft cloth in a delicate circular movement. This will remove dirt and finger smudges. Ingrained dirt cannot be removed.
Incrustations of foreign matter can be removed by scraping with a razor blade or any other sharp instrument. To remove spots, use a cuttlefish bone - it is an excellent abrasive.
If this first cleaning is not sufficient, proceed to the wet cleaning method, making sure that the paper and inks are suitable to withstand washing. Spots can be removed or at least considerably lightened by dabbing these areas with a brush and clean water or a diluted bleaching solution. Total immersion in clean water is often practiced on engravings since they usually take well to such treatment.
In preparation for a bleaching bath, prints should be placed in slowly circulating cold water. Light mildew stains and marks can, in some instances, be removed by simple rinsing. Further cleaning may be done with a mild soft soap.
Wet the print laid face down on glass - apply soapy foam gently with soft brush to the back of the print. If the paper surface remains intact, you can proceed with the front.
Rinse in clear water and ensure complete removal of the soap. Some papers are very fragile and are like tissue when wet. So careful handling means not to lift up the paper by hand but transport in and out of the tray on a sheet of glass or plexiglass. The floating print will adhere to the support when raised from the tray and can be turned over for transferring.
The print can also be washed with a very diluted chlorine solution for a few seconds and then rinsed thorouqhly in water.
Thin papers which look fragile and fugitive in color or ink must not be immersed.
Prints made with carbon ink or pencil can be placed in mild bleach with reasonable safety.
Following the bath, the prints MUST be rinsed thoroughly, to disperse all the chemicals from the paper. Prints should not be lifted by the corners.
The simplest form is by exposure to sun and air.
Bleaching by immersion serves the purpose of of breaking down a stain into colourless matter. If the process is carried out too far (i.e. the paper is left soaking in bleaching solution for too long) , damage occurs as the fibers will deteriorate and ink , lead pencil and pigments will suffer loss of brilliance.
(etchings and engravings are printed with carbon ink, which is insoluble in bleaching solutions.
Fugitive coloured prints (watercolored etchings or works with pastels or ink washes) must not be immersed.
3 MAIN BLEACHES
|sodium hypochlorite (also known as chlorinated soda)|
|USE: for removal of foxing, mildew and discoloration stains||
The bleaching bath is prepared with one half cup of sodium hypochlorate to 2 quarts of water. The tray containing the print is rocked gently to and fro at intervals. The stains will lighten up and gradually disappear. The print is removed as soon as the discoloration has dissolved.
Print must be rinsed in water then transferred to a prepared bath of one teaspoon of sodium thiosulphate crystals mixed in one quart warm water, which arrests the action of the bleach. Leave for several minutes before removing for thorough washing.
|USE: for fragile papers and drawings in chalk which can't be immersed.||
This method necessitates special lab equipment as the gases realeased are toxic and proper ventilation is needed.
Use one tsp. of sodium chlorite and 1 quart water. Add 37% formaldehyde. The solution will turn yellow.About 20 minutes of bleaching removes stains.
|USE: Mildest bleaching agent suitable for delicate watercolors and fugitive ink washes||
Rinsing in water not required.
Mix one teaspoon of crystals to 1/4 warm water. Stir solution until dissolved and apply directly to stain with a brush. Use a piece of blotting paper to cover the dampened stain and place a sheet of glass on top.
Repeat application if needed.
Prints and drawings on fragile paper respond well when lightly sprayed on reverse side.
Chloramine T can also be used for baths by adding 1 tsp to each quart of warm water. Bleaching action is slow. Remove print from bath for close observation until stains are no longer visible
HOW TO REMOVE PENCIL WRITING FROM PRINTS
Pencil writing are easily removed by rubbing the area with compressed bread crumbs or with a soft eraser. In case the mark was made with a hard lead and an intaglio mark was left, the mark can be removed by rubbing the back side of the print with a burnisher or rounded object, to raise back the line. Rubbing the paper too much can sometimes damage the fibres and in some cases, if the paper has yellowed, some discoloration might occur. In this case the entire surface of the print should be lightened.
HOW TO REMOVE COFFEE AND TEA STAINS FROM PRINTS
use 2 or 3 drops of potassium perborate mixed in 2/3 cup of water and stipple with a brush onto the previously dampened stain. When the solution begins to dry repeat stippling. A final beach with Chloramine T will remove last traces.
HOW TO REMOVE GREASE, OIL and TAR STAINS FROM PRINTS
Oil spots caused by greasy inks can be removed by using a fine brush dipped in alcohol or benzene. The print should be placed between sheets of blotting paper which will absorb the excess liquid. Scrape stain to remove particles. Use concentrated solution of pyridine as needed. Benzene, white spirit and ethylacetate are possible cleaners.
HOW TO REMOVE BLOOD AND SAUCE STAINS FROM PRINTS
Organic substances (enzynmes) can render some organic stains soluble through digestion. The application of enzymes to stains is still experimental. Commercial digestive powders can be tried.
HOW TO REMOVE INK AND IRON STAINS FROM PRINTS
Use sodium formaldehyde sulphoxylate powder directly on the dampened stain. Wash thoroughly after. Protect ink signatures during bath by painting over the signature a film of nitrocellulose.
2-3 drops of celluloid 5% in a solvent of equal amounts of amyl acetate and acetone.
HOW TO REMOVE GREASE AND WAX STAINS FROM PRINTS
Scrape wax with knife.Use a petrol bath on the stain area. Brush until clean.
How to treat creases and dents
Creases or folds are hard to remove, but can be softened considerably by dampening the print and then pressing it by hand with blotting paper. Alternatively, a print may be placed between two sheets of blotting paper and run through a press or simply left under a heavy weighted board and left to dry.
Minor creases in a damp print can also be ironed out with warm iron - protecting the back with a cloth to avoid scratches. Engravings and lithographs printed on rag paper take well to dampening by immersion while other papers such as rice, cardboard or sized papers would suffer greatly if dampened excessively. Prints with chine collé and those printed with waterbased inks can only be dampened with a sponge or slightly sprayed on the verso side of the paper.
Rips and tears
Small tears can be joined together when the paper is damp. The two sides can easily be put together again gluing a light piece of mulberry paper (ripped in the shape of the tear and large enough to overlap 1/2 an inch on either side of the tear ) onto the back of the print and pressing it into place. The drying should then be done in a press. Gluing must never be done with adhesive tapes and especially not with scotch tape as it burns the paper irremediably. The glues used for this purpose are rice starch glue (mix one tablespoon of starch 5 tablespoons of distilled water. Heat and stir in a double boiler until thick) or wheat flour glue (mix 250g in one litre of water and bring to a boil for ten minutes). It is also possible to use some synthetic glues although old fashioned vegetable glues seem to work best.
If the tears are many or large, you can use a large sheet of mulberry to cover the whole print.
Torn corners - small warm holes - gaping holes and missing sections can be restored by using a paper of similar tone and texture (tea and coffee can be used as staining agents to tone paper to a proximity of original).
A patch a little larger than the missing area must be cut out in exactly the same shape as the hole. This is done by making a tracing of the missing piece, and leaving slightly larger edges which must be evened out or bevelled (chamfered) and the back edges of the hole or missing area must be similarly chamfered. The chamfered edges of the patch are coated with a small amount of paste and joined at the back. The patch is pressed into position and left to dry under weight.
Prints that have been cut out of their margins are hard to fix since it is necessary to make new margins. These added on margins must be of one piece cut out of the same kind of paper as the original one, glued on slightly overlapping the print area. By adding a false plate mark the print will look in its original state.
Willem Jacobz Delff
The image on the left shows Delff's engraving with its elaborate text. The impression shown on the right has been cut out around the portrait (without the text) and laid down on a piece of paper about the same size as the complete engraving with text. This second sheet has also been given a false plate mark as if it were an early state of the engraving before the inscription. The plate mark was created by embossing and by adding a few touches of ink along the putative plate mark, and the blank area beneath the portrait has been given a light ink wash to resemble plate tone.
inadequate storage may result in paper being exposed to deleterous elements. If works are stored in packets, include silica gel
Works stored for long periods of time should be inspected for silverfish and other insects prone to paper habitations.
QUICK PROBLEM SOLVING
|greasy spots||alcohol, benzene, talcum powder (the spots are first dusted with talcum powder and then the area is placed above a pot of boiling water. The talcum powder is then gently brushed away)|
|varnish or resin spots||acetone, alcohol, or toluene depending on the type of varnish that needs to be removed.|
|grease stains||apply "Pyridine" followed up by a careful rinsing|
|left over adhesive tape pieces||benzene, toluene, or hexane|
|rust||oxalic acid (dangerous)|
|mud||soapy water or ammonia|
|water paint spots||cold or warm water|
|oil paint spots||mineral spirits or turpentine, hexane, toluene|
|acrylic paint spots||acetone|
When a print is treated by applying solvents or substances, these should be applied with a brush making sure that the print is well soaked through. The print must then be placed below a sheet of white blotting paper.
To select the professional best qualified to treat your object, contact the referral service maintained by The Foundation of the American Institute for Conservation (FAIC). They will provide you with a list of conservators in your area that can help you find an appropriate conservator or conservation treatment:
The Foundation of the American Institute for Conservation (FAIC)
1717 K Street, NW, Suite 301
Washington, D.C. 20006
Telephone (202) 452-9545
FAX (202) 452-9328
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