File talk:TLC black ink.jpg

Since a couple of years the company stabilo no longer uses a "mixture" of dye stuffs for their black permanent ink. The black ink consists of a single colour. Instead of the OHPen permanent black the OHPen permanent brown should be used for TLC which is only available in a set of 6 colored Pens. Conditions: TLC Silica gel 60 F254 is used and a mixture of ethanol:water = 80:20 as solvent will give the best results.

see: http://commons.wikimedia.org/wiki/File:TLC_stabilo_OHPen_brown_permanent.jpg