noun
- A reddish-brown iron oxide residue left after the distillation of sulfuric acid; used as a pigment and polishing powder.
Usage: technical; chemistry; plural form of colcotar
Examples
- The chemist collected colcothars from the distillation apparatus.
- Colcothars were historically used as a red pigment in paints and dyes.
- The industrial process produced large quantities of colcothars as a byproduct.
- Jewelers used colcothars as a fine polishing powder for metals.