Varnish Composition, What Varnish is Made Of
The composition of varnish, what is varnish made of.
There are two principal kinds of varnish, spirit and oleo-resinous. The most important spirit varnish is a solution of shellac in alcohol; the American standard is made by dissolving five pounds of shellac in a gallon of alcohol; but this is too heavy for common use, and three and a half pounds is more generally suitable. Shellac is naturally dull orange-yellow in color, and is called orange shellac in distinction from white shellac, which is the same bleached with chlorine.
It is of better quality before bleaching, but, of course, darker in color. Orange shellac varnish may be made in an earthen jar, half full of alcohol; to each gallon of alcohol weigh out three and a half pounds of dry shellac (gum-shellac), in flakes, and at night gently drop this into the alcohol. Do not on any account stir it, not even once. Cover it, and next morning stir it with a stick; avoid anything with iron, as iron quickly discolors it. Once an hour stir it for a minute or two, and by night it will be dissolved.
White shellac is dissolved in a churn, or in a vessel where it is agitated with a mechanical stirrer. Orange shellac will dissolve in 85 per cent alcohol, though stronger alcohol is better; but white requires 95 per cent. White shellac resin does not keep well; it is liable to become insoluble, and should be dissolved as soon as purchased. In spirit varnishes the liquid, or vehicle, is volatile and serves as a means of spreading the resin in a thin, uniform film. Damar is another spirit varnish, and is a solution of damar resin in turpentine.
Next Page: Oleo Resinous Varnishes.
This is Varnish Composition, What Varnish is Made Of.
www.craftsman-style.info is Copyright © 2005-12 by International Styles