If the wood panel is sufficiently heavy, these cleats may be screwed on, but at all events they should be glued on with a proper glue, such as can be purchased in the United States under the name of LePage’s Glue, or Russia Cement; but, in any event, it is quite important, in addition to gluing these strips, to fasten them by means of fine wire nails which may go through to the outer surface, and then be cut off and sandpapered to a smooth finish. A very good preparation of a wood foundation is to fill the wood first with what is known as wood filler. This is a material called Silex, or Silica, mixed in a quick drying varnish. It is thinned down with Spirits of Turpentine, applied across the grain of the wood panel, and after ten or fifteen minutes it is rubbed off lightly, the fine grain of the wood becomes filled up with this Silica or wood filler; and, after twenty-four or forty-eight hours, the surface is then rubbed with very fine sandpaper, which makes it perfectly smooth. Then a thin application of Shellac Varnish is applied; and Shellac Varnish for this purpose is manufactured by taking two pounds of any Orange Shellac to three-quarters of a gallon of Denatured Alcohol. This should not be mixed in a metal container, but should be mixed in a stone jar or glass bottle. In a few hours it will have dissolved, if shaken occasionally. A coat of this is applied to the wood after the fill has become thoroughly dry. Three hours afterwards it should again be lightly sandpapered. After this another coat of Shellac Varnish is applied, both to the front and the back of the wood panel. Three hours after that, it can again be lightly sandpapered, and then it is ready for painting. The sandpaper is essential because it roughens the surface and forms a bond between the pigment and the wood. If you paint on a highly polished surface, whether it be glass, metal, wood or canvas, there is very little bond between two glossy coats, and the chances of peeling are very great; but, if you roughen the surface upon which you are going to paint, there is a contact between the paint and the surface, due to the roughness just mentioned.
Shellac used in priming wood is essential, in order to prevent the resinous matter from evaporating into the painting. But, if a painting should crack, which has been based on Shellac, and a restorer applied alcohol, it is quite obvious that the painting would become badly damaged.
PAINTING ON METAL
ANY metal which has rigidity, such as Copper, Zinc and Aluminum, is good to paint on and is absolutely permanent. Aluminum is the lightest of all the metals and not very expensive. It is readily purchased in any size up to 30″ x 36″ and in any reasonable thickness. The bodies of nearly all good automobiles are made of Aluminum, and when the surface is properly prepared, it holds the paint perfectly and permanently. It can be bought with a so-called egg-shell finish, but it is always advisable, before painting, to rub it very thoroughly with coarse sandpaper or emery cloth. This produces very fine ridges, which hold the paint, and that is the only preparation that Aluminum needs for permanent painting. Copper, Brass, Tin-Plate and Zinc must all be prepared in the same manner by rubbing them very thoroughly with coarse sandpaper or emery cloth, and no further preparation is necessary.
OILS AND MEDIUMS
THERE are on sale a very large number of Mediums for use in oil painting, some of which are essential, but most of which are unnecessary; and, for certain purposes, unreliable. The materials generally on sale—and this is not a complete list—are:
- Poppy Oil.
- Linseed Oil.
- Walnut Oil.
- Nut Oil.
- Pale Drying Oil.
- Dark Drying Oil.
- Spirits of Turpentine.
- Petroleum Naphtha.
- Amber Varnish.
- Copal Varnish.
- Japan Oil Size.
- Mastic Varnish.
- Megilp Varnish.
- Damar Varnish.
and other materials, the compositions of many of which are kept a secret and are sold under proprietary names. As a matter of fact, the painter can get along perfectly, and will have permanent results, if he sticks to Raw Linseed Oil, Turpentine and one Varnish, either Mastic or Damar. I do not mean to say that a Medium like Copal Varnish mixed with certain colors is not a good Medium, for such a material will produce enamel paints which will have a permanent gloss, but when you come to consider that the Old Masters had only from seven to ten pigments ground in a drying oil like Linseed Oil, and that most of their paintings are to-day a complete example of permanence, there should be no reason why the mind of the painter should be clouded with a multiplicity of materials and why many materials should be used which may in time prove detrimental.
Without going into any scientific dissertation on the subject, if you take a strong drier and mix it with many pigments like Umber, Zinc and the Siennas, you will have, apparently, a perfectly dry picture in twelve hours, but you must bear in mind that the drying process, once started with these powerful driers, goes on sometimes for years, until finally the paint disintegrates, because too much drier has been used. It is, of course, oftentimes essential to use plenty of drier, or to use Copal Varnish as a Medium, in order to finish the work so that it can be handled with safety for illustrative uses, but where a painter has a commission to paint a portrait, it its far wiser to use the simple palette and to reduce only with Turpentine and Raw Linseed Oil and let the sun and air dry his picture slowly, normally and naturally.