High Quality Gum Rosin refers to an acidic material and the manufacturer of downstream derivatives depends on its acid functionality, a high acid number is also an indication of good quality. The better quality gum rosins usually have an acid range of numbers. It is a dried and cleaned part of the resin obtained from pines and some other plants, mostly conifer trees. High Quality Gum Rosin is a brittle and transparent brownish or yellowish substance added to the composition to make the mixture elastic.