Art

THE art of repairing and restoring frescoes, as it is now practiced in Italy, is in some respects an entirely new one; and the results are so wonderful that some account of the process seems to be called for. The Cavaliere Guglielmo Botti, of Pisa, is the creator of the modern practice.z He has improved some of the known processes, and invented others, until there seems to be hardly any limit to his skill. The world owes him almost as much for what he does not do as for what he does; for it is a sacred principle with him never to add a line or a tint to what remains of an old work. He never tries to re-create any missing portion, but fills the space with a neutral tint in harmony with the general tone; thinking, with Cavalcaselle, that “a picture injured or wanting in parts is more useful to an intelligent student than a picture finished by the restorer, for this ends by being neither an old work nor a new one.” Before beginning to restore a picture, therefore, he has a large photograph made of it, which will testify that nothing is added or destroyed in the original.

As long ago as 1856, Professor Botti made his first trial on a small portion of the Campo Santo of Pisa, and succeeded so perfectly that he was entrusted with the restoration of much of the work of Benozzo Gozzoli existing there. Then the municipality of Padua summoned him to save the works of Giotto in Santa Maria dell’ Arena, and of Mantegna in the Eremitani. Since that he has restored many other works in various places, and he now holds the appointment of inspector of frescoes for the kingdom. Several pupils instructed by him are at work under his direction, so that the restorations are proceeding as fast as the small amount of funds at government disposal permits, and the art is in no danger of perishing with its discoverer.

Perhaps the most striking example of Botti’s success is to be seen in the upper church of the Monastery of Saint Francis, at Assisi. The frescoes on the ceiling, which Vasari says astonished the world, had begun to fade when he saw them ; and the work of time had since gone on so far that, what with dust and mold, sunken colors, and portions so cracked and loosened from the wall as to seem ready to drop on the traveler’s head as he looked up, little of their beauty could be recognized. Only a portion of them has been restored, and the contrast between this and the untouched parts is so amazing — the colors are so fresh, the designs so distinct — that every one’s first impulse must be to disbelieve the old priest who assures him that there has been no repainting or anything like it. It is said that Mr. Ruskin, who had flown to the rescue when he heard that the Assisi frescoes were threatened with restoration, did entirely disbelieve the old gentleman, and preferred the evidence of his own senses, until Professor Botti led him up to the platform, where he could touch and believe.

Before speaking of details, we may recall the difference between fresco and tempera. In the first the colors are ground in water only, with no vehicle ; so much of the wall as can be painted in a day, and no more, is coated with a plaster of finest lime and marble dust in about equal proportions; the design is traced upon this, and entirely painted while the ground remains fresh ; and as this dries, the colors become incorporated with the surface. The inconvenience of having to finish the picture, or one portion of it, at once, with no chance of corrections or additions, often led the great fresco painters to mix up tempera and fresco in the same work. In tempera painting the colors are ground with size or egg, or some such vehicle (tempera) closely resembling that which scene-painters use. Although convenient, because making it possible to paint at leisure on a dry surface, it has not the imperishable qualities of fresco. With time the walls grow damp ; the moisture and salts of the lime destroy the glue or size; and where this has happened, the colors are now found merely dusted on the wall, as easily disturbed as the down on a butterfly’s wing.

To remove a fresco from its wall and transfer it to canvas, or replace it after cleaning the wall behind, is nothing new. Professor Botti has carried this branch of the art to the greatest perfection. The cracked and blistered surfaces are covered with strips of fine muslin soaked in weak starch, crossing each other in three directions. The whole picture is fastened with some such thin adhesive mixture to a large stretched cloth, the coating is gently and gradually separated from the wall, and the whole tipped forward and laid on a table prepared to receive it. But suppose some parts to be in tempera. The moment the starched cloth was applied to these, the colors would leave the plaster forever. Here it is that the first of Professor Botti’s new processes steps in. Before doing anything except to coax off the dust and cobwebs, he passes over the whole a liquid somewhat resembling the tempera used by the old painters. Careful experiments have led him to the discovery of a tempera which absolutely fixes the colors without changing the tones, and fixes them so perfectly that they will resist sponging with boiling water. Of course there is no risk in pasting the cloth upon this. But this application does more than fix the colors laid on in tempera. It has a magical effect in bringing out the dull, sunken tones all over the picture. The effect is like that of a coat of varnish upon an oil-picture that has dried in, and is quite as marked. It is this which has given to the restored parts of the ceiling at Assisi such a freshness and vigor as deceived the practiced eye of Mr. Ruskin. It should be added that Professor Botti is a skillful chemist, and therefore able to judge of the safety of his application, and that his opinion of its harmlessness is shared by Cavalcaselle and other experts of equal skill whose names are less familiar in this Country.

The whole picture, laid flat upon the table, is slightly dampened and gently rolled and tapped with wooden mallets until it is perfectly flat. Its thickness is reduced by paring off the coarser mortar on the back, until only a few centimetres are left. With a picture of moderate size nothing would remain to be done hut to fasten a stretched stout canvas to the back, raise the whole to its place when dry, and remove the front cloth. But among the restorations of Professor Botti is the fresco and tempera painting of the Last Judgment executed by Fra Bartolommeo in the chapel of the Hospital of Santa Maria Nuova, in Florence, and measuring fifteen square metres. About the middle of the seventeenth century it had been removed to a court-yard, wall and all, and dampness and exposure had since done their work. It was in a deplorable condition when, in 1871, it fortunately happened that the place was needed for other uses ; and after consulting various experts, the head of the hospital called Botti to his aid. The tempera portions were fixed by the means already described ; the blisters and raised parts were replaced at their proper level, and bronze pins were driven through them to hold them firmly down. The other operations, so far as I have described them, were successfully accomplished, and the picture lay face downward on its table, ready to be mounted on a new back. But what to make this of was a question. No canvas would be strong enough ; nor wood either, unless made of an impracticable thickness and weight. Professor Botti devised a very neat and excellent substitute, and a net-work of copper wire, stretched on a frame and strengthened by metal rods behind, proved admirably fitted for the purpose. The stretching-frame, rods, and network were well covered with several coats of oil - paint, and laid on the back of the plaster. Fine tow was worked into the meshes and incorporated with the plaster by means of a cement of quicklime, pounded brick, and a kind of cheese called by the Pisans colla. This was daubed on until the whole formed one mass with the old plaster. When the whole was thoroughly dry, the frame was raised up, and Botti had the satisfaction of inviting the Minister of Fine Arts, who came to inspect it, to test its solidity by striking it with his hand : it resounded like a drum. So far as one can predict, a fresco thus treated must be safe for all time. If placed upon a wall, the air will circulate behind it, and no dampness can strike through. Where the situation exposes the picture to moisture in the air, and especially to salt breezes from the sea, Professor Botti applies a final preparation to the surface, composed partly of a turpentine solution of cera punica, which is pure wax treated in a peculiar way to prevent its ever turning yellow,—a preparation known to the ancients and successfully revived by Botti. There were numerous varnishes already in use for this purpose, but they all gave a lustre to the surface quite out of keeping with fresco. As this encaustic of cera punica is free from this defect, and has been pronounced quite safe by the best experts, its invention must be regarded as an important benefit to the art.

Besides being government inspector of frescoes, Professor Botti has charge of the superb gallery of the Venetian school in the Accademia in Venice, where he can show most interesting results of the modern practice of cleaning oil-pictures. It is at least a dozen years since this simple and perfectly safe method was discovered by Pettenkofer, of Munich. He published details of the process, and was rewarded by the King of Bavaria with a gift of one hundred thousand francs, — and no one seems to have troubled his head about the matter since. At any rate, it has not supplanted everywhere, as it should have done, the plan of rubbing off the old varnish by hand, which too often destroys the delicate glazes which were the artist’s finishing touches. The great Marriage at Cana, in the Salon Carré of the Louvre, is a melancholy proof of the mischief the old style of picture-cleaning can do. The Academy of Venice has many examples of the safe and simple method of Pettenkofer. Some of Tintoretto’s Senators look as fresh as when they left the artist’s studio. Some little landscapes of the Flemish school have been treated with it, and in the dark corners can now be read the name of the painter, proving that they had been hitherto attributed to the wrong hand. When Meissonier lately paid Botti a visit, he politely but distinctly declined to be convinced, until he had witnessed the operation with his own eyes. Then his enthusiasm was boundless. It is a pity it was not aroused before the scrubbing process had invaded the Louvre. The treatment is absolutely safe, even in inexperienced hands, and so simple that it is almost easier to do it than to describe it.

If the picture is dirty on the surface, it should be gently washed with water and a sponge, and wiped quite dry with a soft cloth. Then take a wad of cotton-wool in each hand, one wet with spirits of turpentine and one dry, and gently rub the surface, a bit at a time, with the wet cotton, and dry it with the other, changing the cotton as often as it gets dirty. This will remove all the dirt that is above the varnish. There is nothing new, so far. But the picture will not look renovated yet. This is the business of the Pettenkofer process, as follows. Get a box or tray made of wood, or cardboard for very small pictures, a little larger than the stretching-frame and about three inches and a half deep, with no cover. On the bottom, inside, place a layer of cotton-wool or coarse blotting-paper, half an inch thick or less, and fasten it well down with tacks or crossstrings, so that it will remain in place when the box is inverted. Lay the picture on the floor or on a table, face upwards; saturate the cotton or paper with strong alcohol, making it quite wet, but not so wet as to drip; and then turn the box upside down and place it over the picture. Being a little larger than the picture each way, the box will not touch it, but will rest with its edges on the table or floor. The fumes of the alcohol dissolve the varnish, penetrate through the old coats of it, and clarify the whole. After a quarter of an hour it is well to raise the box a little, and make sure that the paper or cotton does not touch the picture, and that the spirit is not dripping or running down. The box is to be replaced, and left for about an hour. When it is lifted off again, if the surface be as soft and even and the varnish as clear as if just applied, the operation is finished. If parts are still rough or clouded, the spirits should be renewed and the box put on again for half an hour or an hour more, and then the picture may be left to dry like any newly varnished one; and may be stood up while drying, as less likely to collect dust.

Professor Botti does not have his boxes made of the full size of large pictures, but does a portion at a time with small boxes, until the whole surface has been acted upon. But the space covered by the box should be allowed to get hard before beginning on the next square ; for the squares must overlap a little, and the edge of the box might stick to the surface if it were still fresh. A little gentle rubbing or dabbing with a cloth wet with turpentine (not alcohol) removes all traces of the squares.

So far as we know, this process has not been described except in Pettenkofer’s original work, which has not been translated, and does not seem to be as widely known as it should be.