A technical dictionary of printmaking, André Béguin.

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Restoring

outline of article

I. ALTERATIONS OF PRINTS AND RESTORATION.
II. THE METHODS USED IN RESTORING PRINTS.
1. ALTERATION DUE TO INCORRECT HANDLING.
  • A. FOLDING, CRUMPLING, ETC.
  • B. RIPS AND TEARING.
2. ALTERATIONS DUE TO INCORRECT CONSERVATION.
3. ALTERATIONS DUE TO LIGHT DAMAGE.
  • A. YELLOWING OF PAPER.
  • B. DAMAGE TO THE TONES.
4. DAMAGE DUE TO SMOKE AND DUST.
5. DAMAGE DUE TO HUMIDITY.
6. DAMAGE DUE TO HEAT.
7. DAMAGES DUE TO VARIOUS TYPES OF SUBSTANCES.
8. BIOLOGICAL DAMAGE.
I. ALTERATIONS OF PRINTS AND RESTORATION.
The restoring of prints may be said to be the art of making prints resemble as closely as possible the supposed original state they were in before being altered. Restoring is the indispensable other side of conservation* which I have already discussed in the first volume of this dictionary. Restoring works of art has always been done but it only gained considerable importance in the course of the 19th century.
However, the more systematic and scientific approach did not come about until the second half of this century. Restoring is, at present, a very precise discipline. In October 1972 the Lisbon congress was attended by 450 specialists from 30 different countries who met at the Gulbenkian Foundation.
In the course of this congress many papers were delivered concerning the latest restoring techniques.
Any restoring process must necessarily begin with a careful examination of the work to be handled. It is, in fact, of the utmost importance to diagnose the "health" of a print before deciding what treatment must be undertaken. The support (usually paper), the ink, the paints, etc. are examined in function of their age, their characteristics, and their degree of damage. Photographic and X-ray analysis may, at times, add valuable information. At times chemical analysis is used to complete the picture.
Alterations may also have affected the supports (usually paper but sometimes cardboard, cloth, metal, wood, plastic, etc. ), the impression itself (whether it be ink, paint, varnish, crayon, etc. ) or even imprints without any colour (such as gaufferings ). The alterations found in prints can be classified according to the following causes:

Once the problem has been diagnosed it is essential that a specific cure be found for each ailment since a single print may have several types of damage. A print is a fragile object and is quite unstable due to the materials it is made of. Because of its fragility any restoring must be done cautiousiy if one does not wish to do yet more damage. Therefore a print should not be washed unless one has some experience and, furthermore, all delicate work using new products or products whose long term effects are not known should be left to specialized laboratories. Some baths and vaporizing products may also damage a print in a way that will not be noticeable until several years later.
It is not always necessary to restore a print so as to make it look almost new. The restoring of colours, in particular, must be done with a very light hand. An old print that is a little pale has its own charm and the wear and tear of time - if only superficial - may be easier to bear than heavy-handed restoration.
All restoration must be preceded by either disassembling the frame (if the print is framed) or separating the print from whatever support has been used so that only the print is worked on.

II THE METHODS USED IN RESTORING PRINTS
1. ALTERATIONS DUE TO INCORRECT HANDLING.
A. FOLDING , CRUMPLING, ETC.
Prints should not be folded or crumpled but this sometimes happens by mistake or due to ignorance when prints are mailed or when they are packed up. Creases can be removed or at least softened considerably by wetting the paper and putting it into a press* much in the same way as engravings are dried (i.e. between two sheets of blotting paper or, better still, between two boards and a sheet of tissue paper which protects the printed side ) [* drying].
Taille-douce engravings, relief engravings, and lithographies printed on rag paper take well to dampening by immersion but other papers (such as any extremely sized paper, laid paper, cardboard or coloured paper ) as well as prints printed with water base inks or colours can only be dampened with a sponge on the verso side of the paper. Even this kind of dampening must be done carefully. It is better to dampen a sheet of paper several times over rather than to dampen it excessively all at once.
B. RIPS AND TEARING.
If a rip is a simple one in which the two sides can be put together again it is best to glue a light piece of paper onto the back of the print in order to keep the two pieces together. It is yet better to double the print by glueing a light sheet of paper, such as Japan paper, over the entire back of the print. The drying can then be done in a press. It is also possible to glue by calendering using a roller press. The glues used for this purpose are old-fashioned vegetable glues, such as rice starch glue (60g well mixed into one liter of cold water heated and brought to a boil for 5 minutes ) or wheat flour glue (250g well mixed, without any lumps, in one liter of water brought to a boil for ten minutes ). If necessary, one can also add some hot water and some drops of antiseptic (10 drops of formaline [ formaline is a poisonous substance ]. It is also possible to use some synthetic glues in powder form that can be diluted in cold water (such as "cellofas B 3500" which is mixed in the proportion of 24g of glue to one liter of water).
If the rip is more like a hole one must cut out a piece of paper of exactly the same size and shape as the hole. This piece of paper can be cut by making a tracing first. At times it might be made in the margin of the print itself. The piece of paper may be kept in place by glueing a slightly bigger piece of paper to the back of the print. The piece to be inserted can also be cut slightly bigger and then evened out (so that the print and the cut- out are on the same level ) with a paper knife. However, the best system is the first one in which the patch is supported by another piece of paper. After drying the glue and putting the print in a press one can proceede to reconstruct the missing part of the image. This reconstruction is, of course, the most delicate part of restoring (see below).
Glueing must never be done with adhesive tapes and especially not with scotch tape as it burns the paper irremediably.
In some specialized workshops a paper repairing machine (most restorers still prefer to do the job manually ) is used. The missing bit of paper is replaced by a fibrous suspension similar to the one used In the original paper. There is also a special paper, "fitmolux", that can be used for slight tears.
The marks left by banging hard objects on the print can be treated either as a crease or as a tear. In the first case a dent can be removed by dampening and drying in a press. In the second case it can be treated as mentioned above.
Damage due to rubbing is hard to correct because the image has often been harmed. In the latter case the paper must be sized again and in some cases the image has to be retouched, both jobs being such that only a specialist should undertake them.
The sizing of the paper may be done quite superficially, using sandarac powder, or in depth, using gelatine glue (15 g dissolved in one liter of water and heated in a double boiler).

2. ALTERATIONS DUE TO INCORRECT CONSERVATION.
Some collectors and some print owners submit their prints to continual damage either out of ignorance or indifference. The problems in this category are usually not due to creasing or ripping but rather to other causes.
Pencil writing on prints is very easy to remove and can be done by rubbing the area with compressed bread crumbs or with a soft eraser (rubber). If the pencil mark was made with a hard lead and an intaglio mark has been left it may be removed by rubbing the back side of the print with a rounded object so as to raise the line. Unfortunately, it is often a difficult task to erase only a very small area of a print on a slightly yellowed paper as the erased area can become white again. In this case the entire surface may have to be lightened.
Marks made with ink are hard to erase. For all the inks used in writing one can use oxalic acid (or citric acid) diluted with water to the point of saturation. When the ink mark turns red it must be washed with a highly diluted solution of lime chlorate (30 to 40 g in one liter of water). An "ink-eater" is another possibility for which two recipes exist. The first is a red solution:

water.......................... 1000 g
sodium permanganate .. 12 g
sulphuric acid................ 8 g

The second is a white solution:
water............................ 1000 g
sodium bisulphite............ 250 g

If the ink marks are spots or lines they can be removed with a fine brush dipped in the above mentioned solutions or then by using lime chlorate without any water. When the spot or line turns red it must be washed with clean water.
All of these procedures must be carried out very cautiously and it is best to always try them out first on a very small test area to see what happens. When some time has gone by and no untoward reactions have come about one can apply the same method to all of the marks that have to be removed.
Oil spots caused by greasy inks can be removed or at least somewhat reduced by using a fine brush dipped in alcohol, benzine, or ether. In order to avoid spotting marks put the print between two sheets of blotting paper that will absorb the excess liquid.
Prints that have been cut out of their paper margins* are hard to fix since it is necessary to make new margins. The new margin must be cut out of a piece of paper that is as much like the original paper. This is not always an easy task, especially in the case of old prints. These added on margins must be of one piece (all four sides in one piece) and glued on by a slight overlap reaching into the print area (just a few millimeters will do). One can also back the new margin and the image with a third piece of paper as has been mentioned above.
The framing of prints with passe-partout often provokes a yellowing of the central part of a print while protecting the margins. Insofar as concerns the treatment to be followed for yellowed paper please see below (3, A).
Collector's marks are very hard to yet rid of, especially since in some cases they are purposely placed so as to overlap onto the image area itself. Furthermore, these marks are often pushed right into the paper so as to gauffer it somewhat (sometimes they even break through the sheet of paper). In any case, it is best to leave such marks atone rather than risk doing yet more damage by trying to remove them.

3. ALTERATIONS DUE TO LIGHT DAMAGE.
Exposure to light causes two distinct types of damage: yellowing of the paper and damage to the tones.
A. YELLOWING OF PAPER.
A certain amount of yellowing is a perfectly normal process and is actually the patina of an old print. A print that is exposed in favourable conditions will not become excessively yellow [ conservation*]. The only way to avoid any change at all is to keep a print in a portfolio but in such a case the print should, every once in a while, get an airing. Furthermore, if a print is kept in a portfolio one must make sure that it gets neither too dry nor too damp, that it does not get too dusty, and that it not be rubbed excessively. The yellowing of paper is particularly problematic when it is irregular. This happens when it has been illuminated through a window through which a shadow is cast, due to the passe-partout around it, or when there are marks or spots on the glass protecting it.
The progressive yellowing of a print can be slowed up by a kind of bleaching of the sheet of paper.
This is, however, a delicate operation which often requires immersing the print in a solution. Quite obviously such a bath is only acceptable if both the paper and the ink take well to it. Such baths are usually given to engravings and lithographies that have been printed with an oil base ink and that have not been coloured with water base colours.
In order to "bathe" prints the restorer must have basins that are somewhat bigger than the print to be treated. At times a sheet of glass or a frame with a cloth stretched over it is placed in the basin so that the sheet of paper can lie on a flat surface.
In the past prints that had to be bleached were placed between two wooden frames. The pressure of the frames was softened by adding two pieces of paper. A print can also be supported by a light grill or by a sheet of tarlatane.
The first bath in clean, cold water allows one to wet the paper and wash it. Some treatises suggest washing the print with hot water (not boiling) that is kept at a temperature that one is able to put one's hands into the bath without any problems. The paper must also be able to withstand the hot water treatment. In any case, a hot water washing is always preceded by a cold water bath. The sheet of paper with the print on it is placed between two white blotting papers after each bath.
The second or third bath is the actual bleaching bath. Bleaching is done using a variety of solutions:

Local bleaching can be done by using the above mentioned solutions applied with a brush. One can for example, dab each spot with a hydrogen peroxide solution.
It is also possible to vaporize these solutions onto papers that cannot undergo total immersion. Industrial methylated spirit is particularly well suited for all types of papers that must not be dampened but one must first try it out on a similar sheet of paper to make sure that it will cause no damage.
The drying that must follow these bleaching baths and rinsings should be done in a press. Each print should be placed between two sheets of blotting paper. The procedures can be repeated, if necessary, using very diluted baths.

B. DAMAGE TO THE TONES.
The restoring of damaged tones is a very delicate job. First of all because it is technically complicated and secondly because it requires a very light hand, good taste, and a good dose of modesty. The restorer must in no way try to replace the artist whose work has been tarnished by the passing years. Specialists usually do not like to make a print appear new since this can only be done artificially. Usually they limit their work to the reconstruction of missing parts, to glueing rips, and to bleaching the paper. At times, but only very discreetly, they do restore a faded area with faded tones or maybe even generally brighten up the print by touching it up very slightly. However, faded colours are never retouched. What must be sought after is a general balance of tones and lines rather than an hypothetical original state that, in any case, can hardly be recreated.
The restorer must therefore use colours that are as similar as possible to those in the print. Fine brushes are used for dotted work and lines while larger brushes are used for the solid colour areas. A fine drawing pen can also be used for retouching fine lines and dots. Retouching can only be done on condition that the inks used are compatible with the old ones. The restorer must make sure that all of the old inks, paints, and papers will take well to the new ones and that the whole will age well together. Water base colours such as gouache, water colours, and India ink are usually well tolerated by absorbant papers. Oil base colours must be made to be either mat or shiny when used on non-absorbant papers which were printed with very greasy inks, glycerophtalic inks, varnishes, etc.
Al of these jobs are usually carried out by specialists who already have long experience in restoring. The reason is that this type of restoring is by far the most difficult and the most delicate.

4. DAMAGE DUE TO SMOKE AND DUST.
Prints that have been exposed to dust and smoke of various kinds are often dirty, gray, and sometimes even blackened. Cleaning can be done with either a dry process or by washing. Cleaning always begins with a dry method since a dry process is often sufficient.
In the past erasing was done with compressed bread crumbs reduced to a powder in one's hand. This method can still be used because bread crumbs absorb dust very well and once the "erasing" is done the print can be brushed clean. Usually both sides of the paper are cleaned.
Erasing can also be done with a soft eraser (rubber) but in this case the finer lines of the print must not be touched. The eraser must be cut in such a way that small areas can be reached. Hard erasers that are somewhat abrasive must be used very carefully; only on certain spots and on well sized paper. Incrustations of foreign matter can be removed by scraping with a sharp instrument.
If this first cleaning is not sufficient one can then proceed to a wet cleaning which may be either partial or total. Again, make sure that the paper and inks will take well to washing.
It is possible to remove or at least considerably lighten spots by dabbing them with a brush and some clean water or a bleaching solution.
Total immersion in clean water is often practiced on engravings since they usually take well to such treatment. Some treatises on restoring call for repeated washings that must be carried out every 24 hours.
Another possibility is to wash the print with a chlorinated bath (a slight chlorine solution) for a few seconds and then rinse the print thorouqhly in water.

5. DAMAGE DUE TO HUMIDITY.
Humidity can provoke two types of damage. The first type of damage is a directly caused one since the humidity will dissolve the sizing, make the paper buckle, destroys the assembled pieces (glued backings, etc.), and provokes the formation of spots and water marks. The second type of damage is an indirect consequence in that the humidity will favour the growth of bacteria of various sorts and various types of plant life. The damage done by humidity is even greater if the prints are kept tightly packed and covered with tissue paper to set them off and prevent them from staining each other. Excessive humidity can, at times, cause nothing less than a glueing together of these prints especially if damp periods are followed up by dry ones.
The first step in treating a print that has undergone excessive humidity is to isolate it, that is, to remove it from its frame, passe-partout, set off paper, protecting sheet, etc. so that the print is free standing.
The spots caused by humidity are not easy to remove. Here too one may try to wash the print, either partially or totally, depending on the type of spot, the amount of these spots, and the size they may have attained. The washing can be done with cold water or then, in some cases, with warm water.
The spots may also be treated by dabbing them slightly with a cotton tip or a brush dipped in a bleaching solution.
The wrinkling can be lessened by dampening and then drying under pressure. The glueing, backing up, and framing should not be done until the print has dried properly.

6. DAMAGE DUE TO HEAT.
Actually it is a rather artificial distinction when one separates the damage done by humidity from the damage done by heat especially since the destructive effects of heat are often closely associated to excessive dryness and to excessive humidity. In the first case, when heat is very dry, paper becomes very brittle and friable while the coloured areas and the inks become scaly. In the second case, when heat is very damp, various types of plant life may begin to develop. On the other hand, the minute the temperature rises excessively the paper is burned and turns a reddish tinge or is actually burned leaving a well known brownish border area. The restorer's job is all the more complicated if the damage is extensive.
It must not be thought that all papers can be regenerated after suffering from excessive heat. One can, of course, place it in damp but not excessively damp air so that it regains a certain suppleness. However, when a 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. The missing pieces can only be replaced by cut outs. In some cases, and only to a certain extent, bleachings can be undertaken.

7. DAMAGE DUE TO VARIOUS TYPES OF SUBSTANCES.
Greasy spots can be feabsorbed with talcum powder. The spots are first dusted and then the area is placed above a pot of boiling water. The talcum powder is then gently brushed away. If necessary repeat the procedure hut remember that the procedures may be undertaken only after a complete drying in a press has been carried out.
In the past ether and carbon sulphate were used but both are inflamable and, furthermore, the latter has a very disagreable odour. The print treated with these substances is placed below a sheet of white blotting paper. The ether or carbon sulphate are applied with a brush making sure that the print is well soaked through.
At present alcohol and benzine are used more often than ether and carbon sulphate.
In order to remove varnish use alcohol, acetone, or toluene depending on the type of varnish that needs to be removed. The same solvents are used to eliminate resin spots.
Grease stains are eliminated by applying "Pyridine" followed up by a careful rinsing. Left over adhesive tape pieces can be removed using toluene, benzine, or hexane.
Wax can be removed using mineral oil, rust with oxalic acid (dangerous), mud with some soapy water or ammonia, water paint spots with cold or warm water, oil paint spots with mineral spirits or turpentine, hexane, toluene, and acrylic paint spots with acetone.
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. If a paper is excessively acid it will lose its colour after a certain amount of time. It will also grow darker and ends up by destroying itself as the fibrous structure will slowly be anihilated. This problem can be remedied by washing the paper or then by applying some alcaline solutions. [* solvents].

8. ALTERATIONS AND 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:

One of the most often used products for this kind of work is "Thymol" in crystal form which is applied by emanation.
The damage caused by mushrooms and bacteria, as well as that caused by insects and rodents, must be corrected using the means mentioned in the previous paragraphs.
It should be kept in mind that this article on restoration is nothing more than a general survey of the main problems encountered and as such cannot be expected to resolve all of the difficulties entailed in restoring prints. If the reader wishes to pursue the matter he may consult the specific bibliography. It is important to remember that restoration is a specialized science and if it is not done properly it can damage a print for ever. [frame , conservation , washing].
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