Varnish
2 of the 6 encyclopedias on this shelf carry an entry for Varnish. Both are reproduced below, so you can see where they agree and where they differ.
Collier's New Encyclopedia (1921)
a thin, resinous fluid, which, when spread over the surface of wood, metal, glass, or other solid substances forms a shining coating, impervious to air and moisture. The great number of varnishes consist of some resinous material, dissolved in linseed oil, alcohol, or some liquid hydrocarbon such as turpentine and benzole. Those made by dissolving a resin in a nonvolatile drying oil, like that from linseed, are called oil varnishes; and those prepared by using volatile solvents (alcohol, benzole, etc.) for the resins are called spirit varnishes. In the case of the latter the solvent becomes dissipated as the varnish dries, so that when any surface is coated with a varnish of this kind only a film or coating of resin remains, which is apt to crack and peel off; but means are taken either in the preparation of the varnish or in the laying of it on to counteract this tendency. With an oil varnish, on the contrary, the oil remains as part of the coating, giving it toughness, while the resin gives it hardness.
Aiton's Encyclopedia (1910)
var'nish, a preparation used by painters and gilders in coating surfaces. A varnish differs from a paint in that the opaque white lead of the latter is replaced by a transparent gum or resin. The principal resins used for varnishes are lac, benzoin, copal, amber, asphalt, and mastic. When these resins are dissolved in heavy oils, they form a durable, hard, transparent coating capable of resisting the weather. Less durable varnish, used often for inside finish or for varnishing paintings, is made by dissolving a resin in oil of turpentine. The turpentine evaporates quickly, leaving the resin behind in a thin, transparent coat. Alcohol varnishes dry even more quickly than those made with turpentine, but they are less durable. See Lac ; Linseed ; Paint ; Painting Vasco da Gama. See Gama ; Vasco Da
What Has Changed in the Last Century
Both accounts divide the field neatly into oil varnishes and spirit varnishes made from natural resins "lac, benzoin, copal, amber, asphalt, and mastic," as Aiton's put it in 1910. Within a few years of Collier's 1921 entry that basis collapsed: DuPont's nitrocellulose Duco lacquer, introduced for General Motors cars in 1923, cut a finishing job from weeks of brushed-and-rubbed coats to hours of spraying, and the alkyd resins developed in the later 1920s replaced fossil copal and amber with synthetic polyesters. Today's clear finishes are mostly polyurethanes, acrylics and water-borne coatings, and shellac and linseed-oil varnish survive largely in furniture restoration and instrument making. Environmental rules on volatile organic solvents have since pushed the trade steadily away from exactly the turpentine, benzole and alcohol thinners these entries treat as standard.
Written for this edition, 2026.