In the Pharma world, using blue or black pens are the industry standard. I don't recall any standard about which type of pen you should use. I concur other folks mentioned that it should be part of the Good Documentation Practices training for employee training. I prefer using blue pen for documentaion. For example, my signature on the scanned copy is very distinct.
One important aspect of inks is the type of ink... no "eraseable" pen and we stay away from gel ink/"Rollerball" pens because the ink runs easily if you spill something on it. We got dinged on a customer audit because of a smeared signature due to a cleaning agent spill.

