The so-called gums used in varnish making are in reality resins in contra distinction to the true gums. Resins are but slightly, if at all, soluble in water, while the true gums are fully soluble in that substance.

Gum Arabic and dextrine are the most important outside of starch and flour, which, when boiled, present the gummy nature also.

Gum Arabic is a product of the Acacia, growing in some parts of southern Asia, the East Indies and northern Africa. It is a white, or light yellow, transparent gum, soluble in hot water. A standard solution consists of 1 oz. gum Arabic, dissolved in 2 ozs. of boiling water.

Dextrine, or British Gum is prepared from starch by treatment with acid and heat. It is less adhesive than gum Arabic.

Starch is made from grain, potatoes and some bulbous roots, mainly, however, from corn and potatoes. To make starch solution, the best plan is to mix the starch in powdered form in enough cold water to make a cream like paste and add this mixture slowly to boiling water of sufficient quantity to make a jelly-like mass, which can be thinned as desired.