The Gums are exudations from trees. At first they are generally mixed with some essential oil. They are then soft and viscous, and are known as Balsams; the oil evaporates and leaves the Resin, which is solid and brittle.

Resins are often called "gums" in practice, but a gum, properly speaking, is soluble in water, and therefore unfit for varnishes, while resins dissolve only in spirits or oil.2

Gum Resins are a natural mixture of gum with resin, and sometimes with essential oil found in the milky juices of plants. When rubbed up with water the gum is dissolved, and the oil and resin remain suspended.