Black hands is a side effect as a carbon (or part carbon) pole wears. The production of this black residue can be reduced by the following steps:
1. From new keep the pole as clean as possible during use - perhaps wiping the pole hose after each use with the pole, before putting back in the van.
2. Regularly (perhaps at the end of each week) flushing the pole out using a hose pipe.
3. Every couple of months take the pole apart, clean thoroughly and allow to dry. Check and renew any worn overlap tape and base tape (essential to help prevent carbon on carbon wear). Then spray the sections, paying special attention to the overlap area, with a coat of dry-film PTFE spray.
4. When out working if the pole starts to sound gritty then immediately flush the inside of the pole thoroughly with water from the hose pipe.
These steps if carefully followed will help prevent the premature wearing of the inside of the sections which is where carbon wear will occur first.
As a general preventive for black hands I recommend using disposable Nitrile gloves. This not only helps prevent black hands, but also promotes good hygiene and skin health whilst working. I usually go through a couple of pairs a day whilst out at work.