Though it is simple and easy to describe the manner in which old pictures in general are restored, it must be borne in mind that, as regards a detailed and comprehensive description, the task would be the most difficult in the whole range of repairing; for when a picture has suffered so much that repainting is absolutely necessary, then nothing but the skill of the original artist himself would ever do full justice to it. In many cases we have pictures, like decayed works in wood, so far gone that only a mere hint or sketch of the original remains, so that they are generally deemed not worth keeping. In such cases the restorer or repairer may very well do his best. There is, and always will be, an immense field for every skilled repairer in this remaking of antiques, to great profit, because there is an unlimited supply of material, almost everywhere, wherewith to work.
To be a perfectly accomplished restorer of pictures one should be an expert in chemistry, and not only one very familiar with all the styles and schools of art, and gifted with great knowledge of the technique of great artists, but also no mean painter oneself. There is a very general, but very vulgar and stupid, popular belief that the restoration and cleaning of old pictures is a merely mechanical art, about on a par with house-painting as regards skill or intelligence; but this I earnestly deny, having found, since I have practised it myself, that it affords a wide field to ingenuity, and that the greatest artists living—I care not who they may be—can find in restoration tasks which would fully tax all their skill, knowledge, or genius.
Before proceeding to clean or repair a picture it is often advisable for the artist to make an outline sketch of it with great care, in order to correct and guide him in details. To do this, take very transparent tracing-paper—the recipe for making which is elsewhere given—then with a soft crayon-pencil, or a very black lead-pencil (from 3 to 4 B), trace the whole. If the paper be not transparent enough, then use thin glass, or, what is far better, sheets of mica, gummed together at the edges, which will not break even if dropped. Trace the picture on this with a fine brush and black oil-colour, or any black paint which will hold. Then make a tracing from this on transparent paper. To transfer crayon or lead pencil drawing to wood or paper, very slightly dampen the surface of the latter, lay the tracing on it face down, and rub the back of the latter with a burnisher or ivory paper-knife. It will thus be perfectly transferred. This making preparatory sketches or copies will be found in many cases extremely useful, as training the eye carefully to the work to be done.
It is not invariably true, though a great authority on picture-cleaning (Henry Mogford) has declared the contrary—that “pictures ... unquestionably enjoy their highest perfection at the first moment of production.” Many artists recognise the truth that a year, or even years, are needed to give a certain delicate tone, which is like the ripeness of fruit, to certain pictures; and the same is true of certain artists, though by no means in the same degree of all. But there are many persons who can associate the mellowing tones of age or the venerable grey of antiquity with nothing but dirt, decay, and poverty; as was the case with an Italian marquis, who, having heard that a distinguished artist[4] had copied an old moss-grown wall or fragment of ruin on his estate, sent an apology to the latter, stating that if he had known that such a distinguished person intended to copy it he would have had it cleaned and lime-washed, not in glaring white (he knew better than that, he said), but in light blue! So I have known an American gentleman to be distressed at discovering the appearance of lichen on a corner of a “spick-and-span, brand-new villa,” which he at once declared must be cleaned and painted all over. People who suffer from this vulgar mania of over-scouring are apt to imagine that when they detect the least sign of age in a picture it suggests dirt and neglect, and hurry it off to the cleaner; unless, indeed (as is too often the case), they—with insufficient knowledge, and with “notions generally derived from guess-work, and suggested by the usual arrangements for taking care of other household objects”—attempt to restore the work themselves, which has been the cause of the ruin of thousands of great works of art.
It may here be observed that modern pictures, owing to the hurried processes of manufacture and the use of cheap materials in machinery-made paints, change so rapidly that many lose half their value in fifty years’ time. And, as if this were not enough, we have the sulphuric acids generated by coal-fires (especially that from anthracite coal in America, which even eats away the lime in chimneys), as well as the deleterious effects of gas, vapours from food, and, finally, the want of air and light in ever-curtained and shaded rooms.
The causes, in fact, which lead to deterioration in pictures are almost as many as those which produce diseases in man, and in not a few instances they will be found to be the same. These are, as I have said, foul air or malaria, or want of fresh air, dampness, the smoke of candles in churches, too long exposure to sunshine, the exhalations of charcoal, sulphur, sinks, &c.; “in short, all penetrating scents are injurious to painting, especially if it be new.” Owing to this prevalence of gas and coal smoke in houses, allied to the bad quality of paints, as now manufactured cheaply by machinery, it is, indeed, considered doubtful whether any of the pictures painted during the reign of Queen Victoria will exist in “half-visible” condition fifty or a hundred years hence. There is, as regards them, a grand future for the restorer. One need only look at most of Turner’s earlier pictures to fully verify what is here asserted.
The face of all old pictures long untouched will always be found covered more or less with what is simply dirt; that is, dust more or less dissolved by moisture. Now, dust consists simply of all kinds of substances, even invisible extinct animal organisms in vast numbers. The first step is simply to wash away this dirt with distilled or rain water and ox-gall. Use a very soft, clean sponge, and pass it over the picture many times. The last time wrap the sponge in a clean, white linen or muslin handkerchief to see whether the surface is quite clean. This and nothing more will often produce an astonishing improvement.
The next task will be to remove the varnish. Hot water attacks any varnish, reducing it to a dry powder; but, as M. Goupil remarks, this is très hasarde, or is very risky, because it may also attack and dissolve anything like gum or glue in the colours. M. Goupil, however, sanctions the use of cold water in cleaning even to mere abuse, in which he is in contradiction to Henry Mogford, whose work I regard as by far the best with which I am acquainted on the subject of cleaning and restoring pictures which I have read.[5] On this subject he says:—
“During all operations of lining, and of picture-cleaning generally, saturation by water is attended with disastrous effects, and the use of it should therefore be limited to application by means of a squeezed piece of sponge, or, what is better, a piece of buff leather, soaked and wrung out. Water is a most dangerous enemy to pictures; it penetrates to the priming or ground, loosens them by promoting decomposition of the size with which they are worked, and thus lays the foundation for their eventual disintegration and decay. Imbibed damp will sooner or later cause the destruction of every woven material, and while our daily experience shows its lamentable effects on the walls of our dwellings, it will be well for us to remember that it is no less destructive to the canvas of our pictures, and to the materials which form its priming.