Oil Varnishes, made from the hardest gums (amber, gum animd, and copal) dissolved in oil, require some time to dry, but are the hardest and most durable of all varnishes. They are specially adapted for work exposed to the weather, and for such as requires polishing or frequent cleaning. They are used for coaches, japan work, for the best joinery and fittings of houses, and for all outside work.
1 Spirits of wine to which a little wood naphtha has been added to make it undrink. able, and therefore not liable to duty. 2 Holtzapffel.
Turpentine Varnishes are also made from soft gums (mastic, dammar, common resin) dissolved in the best turpentine. They are cheaper, more flexible, dry more quickly, and are lighter in colour than oil varnishes, but are not so tough or durable.
Spirit Varnishes or Lacquers are made with softer gums (lac and sandarach) dissolved in spirits of wine or pyroligneous spirit. They dry more quickly, and become harder and more brilliant than turpentine varnishes, but are apt to crack and scale off, and are used for cabinet and other work not exposed to the weather.
Water Varnishes consist of lac dissolved in hot water, mixed with just so much ammonia, borax, potash, or soda, as will dissolve the lac. The solution makes a varnish which will just bear washing. The alkalis darken the colour of the lac.
Space does not permit here of more than the mention of one or two points that may he useful in mixing varnishes on a small scale. As a rule, it is better to buy varnish ready mixed when possible.