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Old 05-26-2009, 11:16 PM
Howard Klepper Howard Klepper is offline
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There is a very broad usage of 'varnish' in the fine art world that includes just about any clear film coating. In this tradition, those film finishes such as shellac that are dissolved in alcohol are called spirit varnishes. Some in the art world might call nitrocellulose lacquer a kind of spirit varnish; there is alcohol in its mix of solvents.

In the housepaint world, 'varnish' used to mean an oil/resin combination thinned by hydrocarbon solvents in the mineral spirits/naptha category, or by turpentine. This is the usage found among guitar makers. Many of the resins used in these varnishes are synthetics such as urethane and phenolic. But urethane does not have the clarity of many of the other resins used in these varnishes. Those clarity issues seem to have been at least partly overcome in the catalyzed urethane finishes.

Waterborne finishes that behave more or less similarly to the oil varnishes in their application properties are sometimes called varnishes, too.
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