Rosin is a kind of natural resin, coming from pine gum, a reproducible resource in the pinewoods. From a chemistry point of view, it is a sort of solution with resin acid dissolved in terpene. After processing, rosin (with the main ingredient of resin acid) and turpentine (with the main ingredient of terpene) can be produced from it.
         The annual output of rosin of the world is 1.1~1.2 million tons, and turpentine, 250 thousand tons.
Based on different raw materials and processing methods, rosin can be classified as gum rosin, wood rosin and oil slick rosin, while turpentine includes gum turpentine, wood turpentine and sulfate turpentine.

Gum Rosin    which is produced by directly gathering from the pine trees and processing. The production is characterized by continuous gathering, which is beneficial to making full use of the resources. China is affluent in resin resources, and it is the country with the greatest amount of colophony yield. The annual output will keep above 350 thousand tons for the long run. Therefore, it is estimated that in the future 20-30 years, the world’s annual yield of gum rosin will still keep around 650-700 thousand tons.

Wood Rosin which is produced by cutting up the roots and/or trunks of pines, extracting the resin by certain solvent, and then processing. This product is mainly produced in American, depending on the virgin forest in the southeast of the country. Currently, due to the reduction of forest resources available, leading to the deficiency of raw stuff for the production of wood rosin, the annual yield of wood rosin dropped from 316 thousand tons in 1950 to 20 thousand now. The Soviet Russian also has wood rosin output. Because of the feed deficiency, the output is also dropping sharply. It is estimated that the production of wood rosin currently accounts for only less than 5% of the whole rosin output of the world.

Oil Slick Rosin    coming from the recycled black liquid in the papermaking industry using the method of sulfate. In the past, this product is relatively of low quality comparing with gum rosin. Currently, the quality is close to that of gum rosin because of technical improvement. Recently due to the reduction of pine wood stuff in the papermaking industry, the production rate of colophony has dropped from 27% to 21% using oil slick distillation. Therefore, although the capability of rough oil slick distillation increases, the output remains stable, accounting for about 30%-35% of the whole.

Appendix: Method of Water Dropping & Method of Steaming
        Currently there are two major methods: water dropping and steaming for the producing of rosin in the mainland of China.
        Method of Water Dropping: Put the pine gum into a boiler with direct fire heating; drop fresh water into the boiler to speed up the evaporation of turpentine, then there remains the rosin in the boiler.
This method is relatively a rude one. Due to the oversimplified equipment and technique, the quality can’t be guaranteed. The product is dark in color, with a low softening point, and is of low price.
Method of Steaming: This method makes use of overheated water steam to produce rosin. The product is of high and stable quality, high softening point, light color and higher price comparing with the former one. It is suitable for exportation.
       Both being the “first class” rosin, the product coming from the above two different methods has pronounced difference in quality. Before purchasing, one must make clear which class the product belongs to.