- to camouflage the typical appearance (pigments and dyes, e.g. charcoal),
- to interfere with color-based drug tests (mixing thiocyanates and iron salts or cobalt salts forms deep red complexes in solution),
- to make the mixture undetectable by drug sniffing dogs (activated carbon may sufficiently absorb trace odors).
Since the result is usually black, it is generally smuggled as toner, fingerprint powder, fertilizer, pigment or metal moldings. The pure cocaine base can be recovered from the mixture by extraction (freebase) or acid-base extraction (hydrochloride) using common organic solvents such as acetone.
It was reported that in the mid-1980s Chilean dictator Augusto Pinochet ordered his army to build a clandestine cocaine laboratory in Chile where chemists mixed cocaine with other chemicals to produce what Pinochet's former top aide for intelligence Manuel Contreras described as a "black cocaine" capable of being smuggled past drug agents in the US and Europe.
Black cocaine was detected in Bogota, Colombia in May 1998. In 2008, a new type of black cocaine was discovered by police in Spain. It had been manufactured into rubber-like sheets and made into luggage.
- Branigin, William (April 28, 1999). "Cartels Shipping 'Black' Cocaine; Bricks of Drug Look Like Metal Moldings, McCaffrey Says". The Washington Post. HighBeam Research. Retrieved 12 October 2010.
- Jonathan Franklin, Pinochet 'sold cocaine to Europe and US', The Guardian, 11 July 2006
- Davison, Phil (8 September 1998). "Global alert for undetectable black cocaine". The Independent. Retrieved 12 October 2010.
- McNicholas, Michael (2008). Maritime security: an introduction. Butterworth-Heinemann. p. 190. ISBN 978-0-12-370859-5. Retrieved 12 October 2010.
- "New Black Cocaine discovered at Barajas airport". Typically Spanish. Feb 19, 2008. Archived from the original on March 14, 2008. Retrieved 12 October 2010.