Linoleum

Another material which seems to lend itself particularly to decorative and monumental painting is linoleum. This consists of a very strong fabric coated with a thick layer of oxidized linseed oil mixed with cork-raspings and other materials. It thus bears some resemblance to canvas which has been primed for the reception of oil colours, but differs in its greater solidity and in the elastic substances which it contains. The fact that the body of linoleum consists mainly of the same substance that forms the binding material in ordinary oil-painting sufficiently guarantees permanent union between picture and ground. From another point of view the massive nature of the material almost completely obviates the risk of mechanical injury, and affords at the same time complete protection from the attacks of air and damp at the back. If the brown colour be not an objection, the surface can be used just as it is as a painting-ground; in this case the various rough and smooth sorts of linoleum provide an agreeable choice of surfaces from the artistic standpoint. But it will be found better to lay on a thin coat of white oil-paint, especially in the case of pictures intended to present a bright general tone.

Or a white pigment may be incorporated with the mass of the linoleum itself and so the brilliancy of the applied colours may be enhanced. As linoleum is manufactured several yards wide, it is possible to paint very large pictures on a single piece, so that this material seems more suitable for monumental or large decorative works. It should not be fixed directly to the wall, but attached to a metal framework covered with galvanized iron wire netting and erected at a small distance from the wall; the danger of injury from damp or fracture is thus avoided.

With reference to the two materials, linoleum and sheet aluminium, recommended in the preceding paragraphs for use as painting-grounds, a few further observations may be advisable. The variety of linoleum in which the canvas-backing is omitted - solid linoleum - is not suitable for the purpose under discussion, for there is some risk when large pieces are used of its sagging, and even splitting, after the lapse of some time. And the experience of coach-builders is not altogether in favour of aluminium for the reception of a coating of oil-paint. In some instances, at all events, there are signs of the disintegration of the metal and consequent cracking of the superimposed layers of pigment. Possibly these drawbacks may not occur where the painted surfaces are not exposed to the external atmosphere. And it must be remembered that the sheet aluminium of commerce varies somewhat in its composition and properties.

'Willesden canvas' appears to resist the attack of moisture and of animal organisms: the copper-compounds which it contains do not interfere with its use as a paintingground, but the absence of soluble salts (chiefly sulphates) from it should be ascertained. This test is easily made by soaking a piece of the canvas weighing 50 grains in distilled water overnight, pouring off the clear liquid next morning, heating it to boiling, and adding a few drops of barium chloride solution and of dilute nitric acid. If a distinct precipitate be formed the canvas cannot be employed safely, but a mere cloudiness may be disregarded. It is just as well to test the watery extract for free acid by means of litmus paper, because an attempt has been made to remove the green colour of Willesden canvas by a bath of dilute sulphuric acid, the presence of which is, on all accounts, to be avoided. 'Willesden paper' possesses properties similar to those of Willesden canvas, and may sometimes be found serviceable for work in oil-colours.