Painted varnishes are 30% solutions of resins in pinene, with the exception of kopalovy varnish, where kopalovy resin is dissolved in linseed oil. The following types of varnishes are available, used as additives to oil paints: mastic, dammar, pistachio, acrylic-pistachio and kopal.
Mastic varnish. 30% solution of mastic resin in pinene. Mastic varnish can serve not only as an additive to paints, but also by wiping the intermediate layers during layer-by-layer painting, replacing retouched varnish in this. Apply mastic varnish and as a cover for oil and tempera painting. Tends to turn a little yellow over time. Gives the work a glossy finish. Very elastic.
The varnish is damn. 30% solution of dammar resin in pinene with the addition of ethyl alcohol. Dammar varnish is used as an additive to paints and as a topcoat. During storage, it sometimes loses transparency, but when it dries, when the pinene evaporates, the lacquer film becomes transparent. To dilute the lacquer, pinene is used. During aging, the dammar varnish turns yellow less than mastic.
Kopalovy varnish is an “alloy” of kopalovoy resin and refined linseed oil, diluted with pinene. The varnish is dark. The approximate composition of the varnish (in hours): digging – 20, oil – 40, pinene – 40. The varnish is used as an additive to paints. The dried film of kopalovy varnish is insoluble in organic solvents.
In addition to these varnishes, are available: balsamic oil, cedar, balsamic-pentamasil and fir varnish
Coating varnishes are used for coating, oil and tempera painting
Pistachio varnish is a solution of pistachio gum (23%) in pinene with a minor addition of white spirit (diluents No. 2) and butyl alcohol. The advantage of pistachio varnish is the almost complete colorlessness of the varnish film, which is very elastic. The drying speed of pistachio varnish is significantly lower than that of other top coat varnishes.
Acrylic pistachio varnish is a synthetic polybutyl methacrylic resin with the addition of a small amount of pistachio resin. The resins are dissolved in pinene, to which about two percent butyl alcohol is added. The film of acrylic pistachio varnish is almost colorless, has great elasticity and is superior in strength to the films of mastic and dammar varnishes. Drying occurs more slowly than mastic varnish.
Retouching varnish is used to prevent burning during multilayer oil painting, as well as to enhance the adhesion of the colorful layers. Varnish can be applied with a brush or swab.
The varnish consists of 1 part mastic varnish and 1 part acrylic pistachio varnish, dissolved in 8-10 parts of aviation gasoline.
COATING PICTURES WITH LACQUER
Varnishing paintings in oil or tempera paints is extremely important. The tones of the colors in the varnished painting acquire intensity. The colorful layer coated with varnish acquires a pleasant shine, at the same time the picture is perceived more clearly, small pictorial details that are often invisible in matte painting are highlighted and emphasized.
The varnish film plays not only a purely optical role, but also protects the paint layer from the action of aggressive reagents in the air. Such aggressive reagents include hydrogen sulfide and sulfur dioxide, causing a sharp darkening of some paints.
Cover the picture with varnish no earlier than a year from the date of completion of work. During all this time, the painting should be protected from dust, pollution, the effects of tobacco smoke, etc. To cover the painting, one of the coating varnishes is used: acrylic-pistachio, mastic or dammar. Acrylic pistachio is considered the best topcoat. This varnish has a special transparency, high elasticity and does not lose its properties over time. The applied varnish must be fresh, from the moment of release no more than three months can pass, which is checked by the composter on the label.
Before applying varnish – the picture must be cleaned of dust and dried. To apply varnish, wide bristle flute brushes are used, while the width of the flute is selected depending on the size of the painting. For a medium-sized picture, a fleit is usually used, the strip width of which is at least 100 mm, and for a small-sized picture – 45-50 mm wide. The selected flute brush should have a short but unshaved bristle. The thicker the varnish, the shorter the bristles of the fleece should be so that it “tightens” the varnish, that is, it makes it possible to apply it with a sufficiently thin layer. In addition to the flute brush, varnish is sometimes applied with a nylon swab or even just by hand.
To better polish the varnish, it should be applied in a heated form, for which they use a water bath with a water temperature not exceeding 40 °. Sometimes the picture is heated with a reflector, also to a temperature not exceeding 40 °, but this method does not give an even distribution of heat over the painting layer, and the heat of the reflector is difficult to adjust.
To reduce the gloss of the lacquer coating, causing glare, the varnish is diluted with fresh pinene (thinner – No. 4) in a ratio of 1: 1.