PERMANENT FOUNDATIONS FOR PAINTING

MANY a painting decomposes, cracks, chips and otherwise fails, because the foundation upon which it is painted is unstable. There is an enduring feature connected with oil paintings which has been described elsewhere[14] and it is not necessary to go into this subject in this volume; but, suffice it to say, that canvas is the least permanent of all foundations, and there is hardly any one of the paintings by the Old Masters, or even any of the paintings in existence by the Modern Masters of one hundred years ago, that has not been relined; that is to say, the canvas has been mounted on other canvas in order to give it stability and permanence. The principal foundations that have been used have been wood of various types, and metal. Wood really is as permanent as anything in existence, excepting that eventually it becomes either rotted, through excessive moisture, or a certain worm invades it and bores irregular holes through it. The most permanent of all foundations is metal. The Dutch have painted on copper, and where the copper has been rather smooth the paint has eventually curled or peeled. Sheets of Zinc or sheets of Aluminum are regarded to-day as the most permanent foundations for all paintings up to a certain size, but beyond a certain size canvas must necessarily be used. I have always advocated the painting of canvas on the reverse side, to prevent noxious gases from working their way through to the under side of the painting, and the painting of the reverse side of canvas is not as simple as it may seem. In the first place, if a painting is to be protected by painting the reverse side of the canvas, after the painting has been completed, unequal tension takes place and the painting buckles, so it is necessary under all circumstances to remove the canvas from the stretcher and re-stretch it. Then again, Linseed Oil paint must not be used either on cotton or linen direct. Linseed Oil is acid, and eventually rots or decomposes all vegetable fibre. It is for that reason that canvas is always first prepared with a glue solution, which is neutral and prevents the soaking in of the oil paint, so that if the reverse side of the canvas is to be painted, it must be either coated with a glue solution, or, what is equally good, it must receive a thin coating of Shellac Varnish. Glue solutions are made by using a double boiler, such as carpenters use, or such as housewives use for boiling rice or other cereals. A pound of glue or gelatine is soaked overnight in a quart of cold water. This swells the glue and makes it ready for boiling. Then it is placed over the fire in a double boiler and more water added, until it has the consistency of very thin cream. After it has been allowed to cool, it is applied to the canvas. Then, after that, any good mixed oil paint may be applied. I have, however, always recommended a mixture of such pigments which shall neither dry too hard nor too soft and will not eventually become too brittle. For this purpose, the following pigments may be mixed and may be obtained from any reputable dealer in house paints:

mixed with one-half pint of Turpentine, to which one-half pint of raw Linseed Oil is added. This makes a salmon-colored ready mixed paint which dries slowly, evenly and is very impervious, and if the color is at all objectionable and too light, Lamp Black may be added to produce a Chocolate Brown. The Lamp Black should be added in oil without the addition of any further varnish or drier. But this must, of course, be applied over the glue size heretofore mentioned, and at the end of a week the painting can be restretched and will show no corrugations or buckling.

In spite of wood being a more durable painting material than canvas, artists prefer canvas, simply on account of the difference in surface; for, the twill of the canvas gives the pigment an unevenness which causes it to reflect and refract light, much to the advantage of the painting.

Gilbert Stuart, in later life, painted many portraits on panels that were grooved to give the impression of canvas, and he had the surface for many of his panels prepared in such a way as to imitate the weave to which he was most accustomed.