Turpentine, the common name for oil or spirits of turpentine, is obtainable in two varieties, one that is distilled from the sap of the pine tree and now known as gum spirits, the other obtained from the destructive distillation of pine wood, stumps, branches, twigs and knots. The latter is known as wood turpentine and is readily recognized by its extremely penetrating and sometimes tarry odor. It is being used to a limited extent in paint and varnish making, but when so used it is liable to cause trouble with exacting consumers, who do much interior work. Some of these wood turpentines are well distilled and their odor not so very strong, but it really does not pay to handle the goods when gum spirits are moderate in price, the difference being too small. Varnish makers on the other hand use the wood spirits to disguise the benzine odors and on account of the strength do not require as large a proportion as they would require of the gum spirits. However the color grinder should keep clear of the use of wood turpentine especially in connection with coach colors and paints for interior decoration. Before the advent of the many substitute turpentines now on the market, spirits of turpentine were often found to be sophisticated by an addition of anywhere from 20 to 40 per cent kerosene or heavy benzine and yet it should have been a simple matter for some of the paint and varnish firms, that were thus roped in to detect the adulteration. The specific gravity test alone amounts to nothing, because with the heavy benzines this can be readily corrected. But the aniline oil test, next to a regular laboratory examination is the safest quick test to detect adulteration with petroleum. This is based on the fact, that aniline oil (oil of sodium) will not mix with any petroleum or its distillates, but will mix with pure gum or wood spirits of turpentine. The test is exceedingly simple: In an ordinary testing tube 6 x 5/8" pour the suspected turpentine to the depth of about one inch, then pour on top of this aniline oil until two inches are reached. Close tube with a cork and shake it violently for ten seconds or until the mixture is uniform, then set aside in vertical position, removing the cork, and observe the result. If after 5 minutes the liquid is not still uniform in color, but shows two stratums, then the turpentine, be it gum or wood spirits is mixed with a petroleum distillate. Another quick test for purity is to place a drop of turpentine on a piece of white paper. It should evaporate and leave no greasy mark in from 5 to 7 minutes. Specific gravity of pure spirits of turpentine should be .864 to .868 at 60° F.
Rosin Spirit is the first run in the distillation process of rosin oil from rosin and may be used as a solvent. It resembles turpentine in general, but may be recognized by a tarry odor and slow evaporation.
Crude Turpentine or as it is sometimes called gum thus or gallipot is the sap or exudation from the long leaf pine and gum spirits and rosin are produced from it. It is sometimes used in marine specialties, but is not a really good material for the purpose.
Venice Turpentine, an oleo rosin from the European larch tree is by far the best for the purpose named above although 5 to 6 times higher for cost. But it does not fluoresce or turn white, as does crude turpentine.
Petroleum Distillates or Spirits are products from the distillation of the crude or mineral oils. The first or lightest gravity products coming over in the process are what we know as gasolines, and these were graded, according to their volatility, 72° - 76° and 84° gaso-oline. But there is good reasons for the belief, that in the present day demand for fuel for automobiles, motor trucks, motor cycles, etc., as well as for gasoline engines, the oil refiners furnish one grade only, as do many of the dealers on the roadsides, who do not hesitate to sell ordinary benzine for gasoline and kerosene for benzine. While gasoline would act as a solvent, the paint maker will not care to employ it, but will adhere to the use of benzine of the 62 ° type or the heavier benzines of the 49o and 56° variety, which latter serve as a substitute for turpentine.
Kerosene or illuminating oil is of use only in a very few specialties in the paint line, such probably as shingle stains and seam cements for ships or in such other materials, that must keep from drying hard for quite a time. The further products from the distillation of crude oil are simply the paraffine oils, that are further treated and clarified and which then become useful as paint and putty oils.
Other Hydrocarbons or Solvents are derived from the coal tar group and are known as solvent or coal tar naphtha, also as coal tar benzol, but are all related to one another, being simply distillates of tar. Can be had in water white form, but also in rather crude appearance.
The crude light oil or coal tar naphtha is of brown color used for thinning liquid tar for better spreading, as benzine will not mix well with tar. It can also be had in the water white form at advanced cost and is then useful in replacing turpentine in stains. By further treatment it serves as the base for the 90% coal tar benzol, which is very much employed in the lightning paint and varnish removers, as well as for burning in certain lamps. Solvent naphtha or coal tar benzol 160 ° is a trifle heavier in gravity than turpentine and has lately been recommended to be used to a limited extent in certain wood stains, especially for birch wood, cedar, cypress and sycamore. Wood alcohol and denatured spirit of wine are now so well known, that special mention would be out of place.