The alcohol available to wood finishers in earlier days was often of unknown quality, it was usually distilled from wine or brandy, and may easily have contained up to 50% water, as there was no readily available way of measuring the water content in the alcohol. This water causes the varnish to become cloudy, so it was of more than interest sake to measure accurately the purity of the alcohol used in varnish making. An early method was to put a quantity of gunpowder in a spoon and cover with the alcohol to be used for polishing. This was set alight and if, after the alcohol has burnt off, the gunpowder would ignite, it was counted as pure enough to use, if the powder would not ignite, then it contained too much water and would be discounted from use. Later the use of the hydrometer meant that a careful calculation of the purity and water content could be made.
Some of the basis of varnish is natural resins, differing locations of these resins and their differing inherent nature, was the diference for many styles of polishes and varnishes.
- Anime is the archaic name for fossil copal resin. Fossil resins are mined from deposits found underground, they are found in areas of prehistoric forest, and as such the resin is virtually exhausted today. The original resin the word anime refers to copal resin and is no longer available, but Kauri resin, from
, is a certain substitute for the original resin. Kauri resin is a superior quality resin, and makes fine quality varnish, used extensively during the 1800’s as the ingredient in most fine quality varnishes, used in both oil and spirit varnishes. New Zealand
- Balsam is a resin collected from coniferous trees such as pine, fir, spruce, balsam, and larch. It was historically considered an inferior ingredient in varnishes, but was used to give the varnish a high gloss. It may be seen to be refered to in old recipes, as chian turpentine (derived from Mediterranean pines), Strasburg turpentine (derived from German fir trees), and
turpentine (derived from European larch trees). Balsam should not be confused with modern turpentine, the product that is now sold as turpentine, was called turpentine oil or spirits of turpentine, and is a liquid solvent made from the distillation of pine-tree sap. The balsam that is available today, is called copaiba balsam and Canadian balsam. Venice
- Benzoin is a resin from the styrax benzoin tree that grows in tropical
Asia. It was used in spirit varnishes of the 16th and 17th centuries. It has a pleasant odour that is still faintly recognisable on antiques, and for this reason is often added to classic varnishes to reproduce the characteristic smell. In old formulas, it may well be referred to as Benjamin.
- Copal , various resins have been called copal, some types of copal can be mixed with oils to make oil varnish, and the copal varnish sold in art supply stores, is an oil-based varnish. The type of copal used in spirit varnishes is called spirit or manila copal. This resin is harvested from the trees of the Agathis genus, and is used as an additive to give toughness to the varnish.
- Elemi is a soft resin produced by the trees of the Burceraceae family, and is added to varnishes to make them more elastic. In old formulas it may be found to be called allemy, and may be bought in art supply stores.
- Gum Arabic is a resin produced from the trees of the Acacia genus. It is included in some old formulas for spirit varnish, and also is used by artists as a resist, this can also be bought in art supply stores.
- Lavender oil is oil distilled from the lavender plant, and first produced during the 1500’s, being very similar to turpentine oil, but that turpentine oil will not mix with alcohol, while lavender oil will. It is used in spirit varnishes to make the varnish level out and smooth more easily, so the brush marks flow out better. It may also be refered to as oil of spike or spike lavender.
- Mastic is a soft resin that is very clear, with a pale yellow colour that may darken with age, and was used in the past when a pale light-coloured varnish was required or desired. It is harvested from the Pistacia lentiscus tree that grows in the Mediterranean region. The best mastic comes in small drop shaped beads called ‘tears’, these have been harvested while still attached to the tree. The lower grades of mastic have been harvested from the ground, and contain impurities. Mastic can be bought in art supply stores.
- Rosin is the resin that is left after the balsam from the trees such as pine, fir, spruce, balsam and larch, is distilled to make spirits of turpentine, and like balsam, it was considered an inferior ingredient in varnish, but used to give varnish a high gloss finish. In old formulas it may well be referred to as colophony, when it was derived from the American pine trees, or as greek pitch, when it was derived from the
- Sandarac is a brittle resin, derived from the Alerce tree (Tetraclinus articulate) that grows in the
Atlas mountainsof North America, and pine trees (Callistris quadrivalvis), in old formulas, it may be refered to as gum juniper. It was probably the most widely used resin for varnish making, because it is very clear and dissolves easily in alcohol. Since sandarac, used alone, forms a very brittle film, elemi was often added to sandarac varnish to improve its elasticity. Sandarac varnish starts almost colourless, but with age it becomes darker and slightly reddish. The best quality sandarac is harvested while still attached to the tree, and is called ’tears’ of sandarac, the lower grade is harvested from the ground and contains impurities. Sanarac also can be obtained in art stores. Cypress
- Shellac is unique amongst natural resins, since it is produced by insects on a plant. Shellac varies in colour depending on the shellac used. Early varnish formulas used seed-lac, button-lac, or orange shellac, and the varnish produced had an orange or dark brown colour. Seed-lac was considered the best for use in spirit varnish during the 1600’s, and it produced a lighter colour of varnish than the orange shellac. In older formulas, when gum lac is specified, kausmi seed-lac is probably being referred to. When old formulas specify shellac, it is appropriate to use the orange shellac. Lighter coloured shellacs were not available until the late 1700’s, although shellac was used in a limited way for a long time, its dark colour made it less desirable, at a time when finishers were striving for a pale light-coloured finish with the varnish. After lighter forms of shellac became available, it soon became one of the most sort and used components in a spirit varnish.
- Mastic varnish later called mastic varnish for varnishing pictures 1835
- Copal varnish later called copal (oil) varnish 1835
- Copal spirit varnish later called white copal spirit varnish 1856
- Fine picture copal varnish 1835
- White spirit varnish 1835
- Brown spirit varnish 1835
- Transfer varnish 1835
- Double mastic varnish later called doble strength for Magilp 1840
- White lac varnish also called lac varnish 1840
- Crystal varnish later refered to as crystal or map varnish 1840
- Caustic or transfer varnish 1840
- Raising varnish 1840
- Roberson's fixing liquid for chalk and pencil drawings, in bottles 1840
- Grecian varnish 1840
- Field's white lac varnish 1870
- Photographic varnish for negatives 1870
- Amber varnish light 1883
- Amber varnish dark 1883
- Soehnée varnish 1883
- Soehnée Frére's varnish for pictures 1890
- Soehnée Frére's varnish for paper and etc. 1890
- Picture copal varnish 1890
- Paper varnish 1883
- Vibert's vernis á retoucher 1896
- Vibert's vernis á tableaux 1896
- Mastic varnish No 2 for pictures 1896
- Rowney's picture glaze 1907.