The solid, resinous residue left after the distillation of turpentine (oil) from balsam. The balsam exudate or gum thus, is usually from the longleaf pine (Pinus palustris), Cuban pine (Pinus caribaea), loblolly pine (Pinus taeda), cluster pine (P. pinaster), or Scotch pine (P. sylvestris). Rosin, also called colophony, is a brittle, clear resin with a color ranging from yellow or reddish-brown. It becomes sticky when warm and has a faint pine-like odor. Primarily composed of abietic acid (about 80%), rosin reacts in hot alkaline solutions to form rosin soaps. Rosin weathers poorly, becoming oxidized and brittle with age. It also has poor moisture resistance. Although many of its aging properties are undesirable, rosin was used as an ingredient in paint, varnish, ink, adhesive, sealing wax, soldering flux, and linoleum. Because it increases sliding friction, it is commonly used for coating bows of some stringed instruments, and as a slip preventative on the floors of stages and shoes of dancers. The inexpensive resin is also used for sizing paper.
Synonyms and Related Terms
"colophony; colofonia (Esp.); colophane (Fr.); colofonia (It); Greek pitch; wood rosin; sound glue; balsam; gum thus; pine resin; yellow resin; abietic anhydride; violin rosin; colophonium; gum rosin "
Soluble in ethanol, acetone, turpentine, acetic acid, carbon disulfide. Insoluble in water. Saponification number = 150-200; Acid number =150-180.
Hazards and Safety
Dust may cause irritation to skin, eyes and nasal passages. Oxidizes easily and may blacken with age. Combustible, burning with a yelow, sooty flame. Evolves irritating and suffocating fumes on heating.
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