Notebook

Notebook, 1993-

MATERIALS & METHODS

Thompson, Daniel V., Jr., Research and Technical Adviser, The Courtauld Institute of Art, University of London. The Practice of Tempera Painting. New Haven: Yale University Press. 1936. Fourth Printing, 1946.

The Practice of
Tempera Painting - Permanence



Permanence of Tempera Painting
Given good workmanship and good materials, and a reasonably healthy environment, a tempera painting may be expected to keep its essential character unchanged for centuries. It is more permanent than oil painting; far more permanent than any painting which can be done with the conventional materials of modern oil painting. It will not survive protracted extreme dampness; it is not fireproof; it can be injured mechanically; but it is extremely durable, and any troubles which may beset it in old age are usually readily repaired. Paintings in tempera which have knocked about for six or seven hundred years are far more nearly in pristine condition than many paintings in oil executed since the Great War. Egg tempera provides perhaps the most durable, unchanging painted surface that a medium useful for picture painting can produce. [p. 120]


Importance of Varnish
For protection against surface dirt, atmospheric gases, and moisture, however, the painting should be varnished. It is neither necessary nor desirable to varnish any burnished gilding than the composition may contain, but the painting proper should have the protection of a coating of hard resin. The best resin for this purpose is, in my opinion, mastic. A mastic varnish affords good protection to the surface for twenty or thirty years, and at the end of that time may easily be removed and replaced without the slightest injury to the painting. It requires care in application to produce a good result and the following method should be followed. [p. 120]


Cleaning the Surface
First, allow the painting to stand for at least a year before you varnish it. Then wipe the surface carefully with a silk cloth, to remove any dust which may have collected upon it. If there is any oil mordant gilding, apply two coats of weak gelatine solution locally, with a small brush, to protect it from solvents which may be used later on in removing the varnish. Wipe the surface of the painting lightly with absorbent cotton damped with fresh pure turpentine, to remove any grease or soot. [pp. 120-121]


Precautions Against Dust and Damp
The room used for varnishing should be given up to it entirely and not used for any other purpose while the varnishing operations are going on. Every precaution should be taken against dust and draughts. The floor should be swept up with oiled sawdust, and the surface of the bench or table upon which the picture lies should be wiped with an oily cloth. The temperature of the room should be, if possible, as high as 70, and the picture, the varnish, the turpentine, and the varnish bowl and brush should all be left there together for [p. 121] a day or two before varnishing. The varnish brush should be washed thoroughly with pure turpentine, rubbed out as dry as possible on a piece of brown paper [not newspaper], wrapped in brown paper, and fastened with a rubber band. [pp. 121-122]


Choice and Care of the Varnish Brush
The varnish brush should have long bristles, and be large in proportion to the work. If you have to avoid a background of burnished gold, you may find it convenient to have a second brush to begin with, say one inch wide; but in general no varnish brush should be narrower than three inches. If you are varnishing a whole panel, brush the varnish on first form side to side as quickly as possible, and then strake it out with firm, even strokes from top to bottom. Do not touch back on the varnish, no matter what happens. If you have missed a spot, or let a drop fall on the finished part, or made any mistake of that sort, wash the varnish off with turpentine, let it dry overnight, and start again. Never wash a varnish brush with soap and water, and never let it dry. Clean the varnish out with turpentine, or petroleum, and if you use it infrequently, so that it might dry out, oil it with raw linseed oil. Wrapped tightly in brown paper, it will stay soft for a long time, and need only be washed out thoroughly in turpentine to prepare it for use again. Varnish brushes improve with age when treated in this way, and an old brush is much easier to do a smooth job of varnishing with than a new one. [p. 122]


Applying the Varnish
After a day or two, the picture and the varnish and implements will have come to an equilibrium in temperature, and any dust in the room will have had a chance to settle. Enter the room quietly, so as not to raise any dust in walking. Wipe the picture again with a bit of cotton damped with turpentine. With the same damp cotton, wipe out the varnish bowl, and pour into it a generous amount of picture mastic varnish, a solution of gum mastic in turpentine. Add to this an equal quantity of pure fresh turpentine, and mix the varnish and the turpentine very thoroughly with the varnish brush. Thorough mixing is very important; it should be continued for several minutes. If the mixture seems in the slightest degree thick or sticky, add a good deal more turpentine, and continue the mixing. Then brush it onto the panel as quickly, as thinly, and as evenly as possible. Throw away your varnish mixture, wash out the bowl and the brush with three or four small lots of turpentine, rub the brush dry on clean brown paper, and wrap it up again. Then leave the room quietly. After twenty-four, or better forty-eight, hours, repeat the process; and if when the second coat of varnish is dry it is not perfectly smooth and shiny, apply another coat in the same way. Do not try to varnish in one coat. Thin coats brushed out smoothly are very much better than a thick coat. [pp. 122-123]


Flatting the Surface
The surface of a newly varnished picture is brilliantly shiny. This shine grows less of itself in the coarse of a few months; but if you want to make the surface matte, you will need to wax it. The use of wax over a thin mastic varnish adds to the protective power of the varnish, and preserves the painting perfectly. The best way to apply the wax is in solution. Dissolve some pure, genuine beeswax, unbleached, in refined benzole, by putting them together in a bottle and standing the bottle in hot water. While the mixture is still warm, paint some of it thinly over the varnished painting, using a broad soft brush. As it cools and dries it forms a hard matte film over the varnish which may be left as it is or given a slight luster by polishing with a soft cloth. Varnish can be flatted by rubbing down with tripoli and oil; and for small painting that is often more satisfactory than covering it with wax. But when wax can be used, it is an advantage; for it can be washed off at any time, and the surface of the painting cleaned in the process. Never use the so-called "matte varnishes." They do not provide adequate protection. [p. 123]


Function of a Frame
Panels which are not self framing or designed to fit into some definite architectural setting generally require frames to show them of. In designing a frame, the effort should be to keep the picture from running into the wall, and the wall from running into the picture. A frame should try to present a maximum of contrast with the picture and the wall on which it hangs, in scale and color and texture. As pictures and walls usually contrast rather strongly with each other in these respects, the frame is apt to be as harmonious with the one as it is contrasting with the other; so this principle is often not recognized. A burnished gold frame may usually be counted on to contrast with both picture and wall; and is therefore a solution of wide applicability. But if a painting contains burnished gold, it may be worthwhile to use matte gold in the frame, or not use gold at all. The long established convention of the gilded frame has certainly begun to lose its force; but as it still possesses some vitality, we may consider its technical side. Burnished gilding has been discussed above; let us examine the possibilities of matte gilding. [p. 124]


Matte Gilding
There are two ways of getting matte effects in gilding, one water gilding, the other oil gilding. The former is far more durable and beautiful; the latter, less than half as troublesome and expensive. They are both useful for frame gilding, and that is the only use most painters will make of either. This is not the place to go into the refinements of frame gilding, such as the combination of burnished water gilding with oil gold, but the essential principles of the art may be outlined, as far as they differ from the practice of burnished gilding already described. [p. 124]


Water Matte
For matte gilding with water, the frame is prepared with bole and size as if for burnish gilding, and gilded once in the same way. Any areas which are to be burnished may be finished at this stage. Parts which are wanted matte should be painted over thinly with a one-to-twenty-five solution of gelatine mixed with about a third of alcohol. This mixture is called a "clear coat." In the hollows, occasionally, and for a cheap effect, all over, the first gilding may be left in this condition. For a really fine matte, however, the whole surface should be regilded over the clear coat. To preserve the finished gilding, which is rather delicate, a thin coat of clear lacquer should be passed over it. [p. 125]


Oil Matte
The practice of oil gilding is simple, and well adapted to the production of satisfactory frames of large size with gold or other metal leaf. The frame is drawn up in the gesso as usual, and finished with as much care as the gilder wishes. It is then given several coats of size or perhaps more conveniently several coats of very thin shellac, enormously diluted with alcohol. It is then coated thinly and evenly with an oil gold size. Excellent commercial preparations for this purpose are available, and are usually so adjusted that they may be gilded at the end of twelve hours or at any time within eighteen hours, or in some such convenient way.

For oil gilding it is convenient to have long leaves of gold, a size larger than is usually used for water gilding. "Transfer gold" may be used for oil gilding--and for nothing else--but it costs more, is usually more extravagant to use, and possesses no advantages for the indoor worker, provided he has learned to handle leaf on the cushion. It is important in oil gilding that the overlaps of the leaves should all lie in one direction, so that they may be pressed down in the skewing, and not ruffled up. In order to be able to gild the hollows without having the gold catch on the tops, it is usual to gild the tops first, all around the frame, working always in one direction. The gold may then be allowed to slide over the parts already [p. 125] laid down into the deepest hollows. In gilding curved surfaces, the gold is not picked up flat on the tip, but simply lifted by having an eighth of an inch or so at the edge of the leaf attached to the hairs of the tip. [pp. 125-126]


Skewing Down
When the whole frame has been laid in leaf, a camel's or badger's hair brush is drawn lightly over it in the same direction as the gilding, to press the leaf down upon the size. With a camel's hair mop or duster, the loose gold is then lightly swept along the moldings, and skewed over the tiny places which may have been left bare. Do not try to cover a spot of any size with skewings, but lay a bit of leaf on it. Break up the skewings as slowly as possible; for the fine dust does not cover as well as large bits. Continue the skewing for a long time. The continued light pressure of the brush is essential to a good effect. The gold is pressed into perfect contact with the size, the skewings attach themselves to any tiny open spots, and the whitish look of the freshly gilded moldings give way to an agreeable polish. The skewings should finally be collected [a large clean paper under the frame makes this easy], and saved; for in the course of time one accumulates enough waste gold in this way to be well worth sending back to the gold beaters for an allowance against the cost of new leaf. [p. 126]


Frame Edges
The outside flat surface of a thick frame is usually better painted than gilded. For this purpose, mix powder color [usually ocher, or ocher and umber] with some one-to-sixteen gelatine solution, and apply two or three coats, cold. This dull color often looks and wears better than gilding on the outside of a frame; and it can easily be renewed if it gets worn or dirty. [p. 126]


Antiquing
Particularly on oil-gilded frames, it is often desirable to do some toning or "antiquing." This may range from a slight modification of the color, to bring the frame into harmony with the painting, to the most dire imitations of the disasters of centuries of wear. In either case, leaving out of account methods of deliberate fraud, the system is the same. Color is applied with size. Those who care to do so may rub a little of the gold off the tops and corners of a water gilded frame, to suggest wear, and to let the red bole show through. A damp cloth is good for this artistic operation; or a fine abrasive, such as emery powder, may be used. Oil gilding should be allowed some time to dry and harden before any further treatment is applied, and should then be given a clear coat of one-to-sixteen size, repeated if it seems necessary, to protect it.

The water gilded surface, or the oil gilded surface covered with a protective coating of size, should next be given two or more coats of very thin shellac. Some color may be added to the shellac if desired, to alter or deepen the color of the gold. Alcoholic solutions of gamboge and dragonsblood are usually used for this purpose, but Bismarck brown and other dyes may be employed. When the shellac is dry, colors are mixed with size exactly as for tinted papers, and painted over the surface with a bristle brush. The brush strokes may be allowed to show, or they may be stippled out with a badger blender. Repeated coats may be applied, and all manner of trickery introduced. The tops of the gilding may be wiped off between coats; colors may be salternated; dry powdered colors may be rubbed on the dry coats of size paint to simulate dust or to change the tone a little. The final product may be given a light coat of wax to preserve it, or left as it is.

Nothing in the way of fancy treatment, however, can produce anything like the richness and beauty of good gilding naturally aged. Good water gilding improves rapidly in color and surface. It may seem a little garish just at first, but two or three years will bring it down to a tone which no faking can equal. Those who admire a decrepit quality in frames will find that raw umber, chalk, and ultramarine blue will give appearances of the most hoary antiquity. [p. 127] Those who admire richness will rely upon dyes in the shellac, and glazings of red bole, burnt umber, Vandyck brown, and burnt and raw sienna. Those who are struck by the harmony of silver frames with blue or other cool color schemes will find That the "oxidized-silver" effect can be produced on a ground of burnished silver by the use of gilders' gray clay and lampblack. [pp. 127-128]


Other Frame Materials
Having suggested the trickeries of these arts, I cannot refrain from saying that I see more virtue in a painted frame than in a metal frame sodden with antiquing. I will not speak of the metal bronzes; for they are certainly not fit for serious use. But paint, white or colored, frankly and decoratively applied, seems to be the logical solution of the frame problem for those who cannot bear the sight of uncontaminated metal. If you want to paint a frame, mix your colors with size, and apply them over the gessoed molding. Wax them a little with beeswax made into a paste with turpentine, and polish them or not, as you please. If you want a metal frame, use gold or palladium leaf. Aluminium has its uses; but I have never seen it look well on a frame. If you want other metals--copper, silver, or pewter--have the frame covered with foil or thin sheet metal, and lacquer it if you want to keep it from tarnishing. Then if it does tarnish, it can be cleaned and made like new.

For white frames, the gessoed wood is sometimes left untreated, or merely waxed; but a more satisfactory and durable white finish may be obtained by painting the gesso with titanium white mixed with a one-to-twenty size solution. Dark colors scumbled over with lighter colors or white are sometimes highly successful. To protect these finishes, it is wise to apply a little thin shellac, and then beeswax. [p. 128]

[Thompson, Daniel V., Jr., Research and Technical Adviser, The Courtauld Institute of Art, University of London. The Practice of Tempera Painting. New Haven: Yale University Press. 1936. Fourth Printing, 1946.]




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