Varnishes
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Purpose of a Varnish
A varnish is a transparent, hard, protective film primarily used to provide a protective layer over artwork. Varnishes are traditionally a combination of drying oil, resin and solvent. Varnish finishes are usually glossy but may be made to produce satin or matte surface by the addition of "flatting" agents. Varnish has little or no color, is transparent, and has no added pigment, as opposed to paint or stain, which contains pigments or dyes and generally range from opaque to translucent. Varnishes are also applied between layers of paint to isolate them or over substrates, such as wood, to seal them and reduce absorbency.
Varnishes are applied to artwork for different purposes. Varnishes can change the surface appearance, making the surface more matte or glossy, or to unify areas of a painting with a more unified surface appearance. Varnishes applied over paint with high pigment concentration, such as tempera, increase color saturation. Varnishes protect the underlying surface and allow the painting or object to be cleaned. They are also can consolidate artwork, in a similar manner to a fixative for charcoal or pastel. Some varnishes provide additional protection in the form of Ultraviolet Light Stabilizers (UVLS), which dissipate UV radiation before it can penetrate to the paint layer where damage may occur. These varnishes are especially useful for materials that are fugitive, such as dyes, but will not render them completely lightfast. The thicker the film of varnish with UVLS, the greater the protection afforded.
Varnish Properties
Varnishes should be removable to allow for cleaning without damaging the underlying surface. The use of a removable varnish provides a valuable tool to anyone trying to restore or clean the painting by allowing it to be solubilized and removed, taking with it any surface contamination. The varnish must be flexible enough to move with the painting surface, yet be hard enough to resist retention of grime and dust by providing a nontacky surface. Depending on the substrate and environmental conditions, it must be formulated with the correct porosity to either allow moisture to pass through or provide a moisture barrier. It should have good chemical and water resistance. Over time it should resist discoloration caused by factors like humidity, heat and visible and ultra violet (UV) light sources. Finally, the varnish must possess excellent clarity, without discoloration or fogging.
Varnish Appearance
Due to differences in the refractive index of the varnish and the surface underneath it, varnishes alter the appearance of artwork and hence serve an important aesthetics function. A varnish that does not alter the appearance of the painting cannot be completely achieved. Varnishes are most successfully employed that compliment the painting. Varnishes are offered in a range of finishes, from gloss to matte, to allow the artist control the final appearance of the work of art. Different finishes of the same varnish type can usually be combined, or used sequentially, to achieve the desired level of surface sheen.
Varnish Types
Besides traditional varnishes based on natural resins, such as dammar, copal and mastic, newer varnishes based on synthetic resins, such as ketone, aldehyde, polyvinyl alcohol, polybutylacrylate and sold under such names as Laropal K-80, PVAA/AYAB, PVA/AWAB, Mowilith 20PVA, Ketone N, Arkon P90, Regalrez and Polybutylmethacrylate, are available to artists. These materials are used by conservators for their suitability as a varnish for modern and earlier works of art.
The most important traditional varnish is dammar. It is the only traditional coating system that is still widely used and recommended as suitable for artwork. Other resins, such as copal or mastic, although still in use, suffer from cracking, extensive yellowing, and become increasingly difficult to remove from a painting over time. Although dammar does turn yellow to brown within about fifty years of normal exposure conditions, it is still removable from an oil painting surface without greatly affecting the paint layers below.
Spirit Varnishes
A spirit varnish consists of a resin and a solvent. After the varnish is applied the solvent evaporates leaving a continuous film of hard resin. In traditional varnishes, resins are derived from plant or insect excretions, are dissolved in a suitable solvent, and called a spirit varnish or solvent varnish. Traditional resins include amber, dammar, copal, rosin, sandarac, elemi, benzoin, mastic, balsam and shellac. The solvent may be alcohol, turpentine or petroleum-based. Some resins are soluble in both alcohol and turpentine. With certain resins, petroleum solvents, such as aliphatic solvents (i.e., mineral spirits, kerosene) or aromatic solvents (i.e., xylene, toulene, V&PM naphtha), can substitute for turpentine.
Over the centuries, many recipes were developed that involved a combination of resins, drying oils, and other ingredients, such as wax. These impart special qualities to the final varnish film, such as increasing the matte or gloss of the varnish.
Synthetic resins, such as phenolic, rosin ester, aldehyde, ketone, etc., gradually replaced natural resins in commercial varnishes because of their properties to resist yellowing and can be more easily removed from the picture.
Neil's Best Dammar Varnish
Neil's Best Dammar Varnish is traditional varnish of dammar resin dissolved without heat in pure spirits of gum turpentine and aged one year. Use Neil's Best Dammar Varnish as a final glossy picture varnish over well-dried oil paintings, after 6-12 months, or add Wax Paste for a satin finish. Add to oil colors for luminosity, use to make egg-oil emulsions or as quick-drying paint medium.
Resin Content: 31% resin weight/volume
Available in 8 fluid ounce (236 ml) conetop cans.
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Dammar Picture Varnish
Dammar Picture Varnish is varnish of dammar resin dissolved without heat in blend of aliphatic and aromatic solvents to minimize yellowing. Add UV Stabilizer to inhibit yellowing caused by ultraviolet (UV) light. Use Dammar Picture Varnish as a final glossy picture varnish over well-dried oil paintings, after 6-12 months, or add Wax Paste for a satin finish. Add to oil colors for luminosity or as quick-drying paint medium.
Resin Content: 31% resin weight/volume
Available in 8 fluid ounce (236 ml) conetop cans.
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Dammar Matte Picture Varnish
Coming soon!
Isolating Varnish
Isolating Varnish is a mixture of sandarac and mastic resins. Isolating Varnish dries fast to a clear finish. Ideal for isolating paint layers, as a fixative and to reduce absorbency of grounds. If necessary, can be thinned with denatured alcohol.
Resin Content: 10% resin weight/volume
Available in 8 fluid ounce (236 ml) conetop cans.
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Sealing Varnish
Sealing Varnish is a varnish of Manila copal and elemi gum (a plasticizer) resins in ethyl alcohol. Dries fast to a hard finish that resists turpentine and mineral spirits, sands easily, making it ideal for sealing wood panels and absorbent grounds. The properties of this varnish are 1) relatively hard resin (copal) used in the formulation; 2) rapidly penetrates into the pores of wood and other porous materials; 3) easy to apply whether by brushing or spraying; 4) complete and rapid drying (due to the low solvent retention); and 5) easy to sand. If necessary, can be thinned with denatured alcohol.
Resin Content: 26% resin weight/volume
Available in 8 fluid ounce (236 ml) conetop cans.
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Oil Varnishes
Oil varnishes typically consist of a drying oil, resin and solvent. There are many different types of drying oils, including linseed oil, tung oil and walnut oil. These contain high levels of polyunsaturated fatty acids that harden through oxidation. Resins typically used in oil varnishes are either derived from natural sources, such as amber, copal, mastic, dammar and sandarac, or consist of synthetic substances, such as alkyd, polyurethane, ketone and aldehyde.
Oil varnishes do not harden in the same manner as do spirit varnishes through evaporation. Drying oils cure through an exothermic reaction between the polyunsaturated portion of the oil and oxygen from the air (called autoxidation). Originally, the term "varnish" referred to finishes that were made entirely of resin dissolved in quickly-evaporating solvents, either ethyl alcohol or turpentine. The advantage was that spirit resin varnishes dried very rapidly when compared to oils; in most cases, they cure practically as soon as the solvent has fully evaporated. By contrast, untreated or raw drying oils may take weeks to cure, depending on environmental factors. In modern oil varnishes, partially polymerized drying oils with added siccatives or dryers have cure times of less than 24 hours. It has long been a practice to combine drying oils with resins to obtain favorable features of both substances in a varnish.
After being applied, oil varnishes harden after evaporation of the solvent and by chemical reactions between the drying oils and oxygen from the air. Oil varnishes remain liquid even after evaporation of the solvent but quickly begin to cure, undergoing successive stages from liquid or syrupy, to tacky or sticky, and to "dry to the touch" and "dry hard." Environmental factors, such as heat and humidity, play a very large role in the drying and curing times of varnishes. In traditional oil varnishes the cure rate depends on the type of oil used and, to some extent, on the ratio of oil to resin. The drying time of oil varnishes may be hastened by exposure to light or heat. Many varnishes require organic solvents, such as turpentine or mineral spirits, to hasten drying, as well as the use of metallic driers. All drying oils and certain alkyds produce heat during the curing process. Therefore, oil-soaked rags and paper can spontaneously ignite if piled together, or, for example, placed in a container where the heat cannot dissipate.
Artist's Virgin Copal Varnish
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Hard-Drying Oil (Olifa) Varnish
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Water-Based Varnishes
Crystal Water Varnish
Crystal Water Varnish is a gum arabic varnish that adds luster to a watercolor painting and saturates colors. It adds gloss to the surface of watercolor paintings and allows glazing of watercolors without lifting the paint underneath. Use it over darker colors to increase color depth and saturation. It is based on recipes used by watercolorists of the 18th and 19th centuries.
Contains natural ingredients. Does not contain organic solvents. Can be thinned with water.
Available in 8 fluid ounce (236 ml) bottles.
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Lac Water Varnish
Lac Water Varnish is a natural resin varnish that can be used as a fixative on watercolor and tempera painting to isolate painting layers, in glazing techniques and to enhance color saturation. It can also be used to reduce the absorbency of traditional gesso and chalk grounds. It is based on a recipe used by watercolorists of the 19th century.
Can be used in combination with the Crystal Water Varnish to "fix" the paint layer before applying Crystal Water Varnish.
Contains natural ingredients. Does not contain organic solvents. Can be thinned with water.
Available in 8 fluid ounce (236 ml) pump spray bottles.
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Casein Fixative
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