If you look at a Scruggs or Frey tip on a new shaft they have made they use Triangle tips and they are always black on the sides. The triangle and elkmaster tips look real grey unless you black them out. I have been using a black sharpie for years with no problem. I trim and burnish the tip good before applying the sharpie to the sides and let the marker dry a min or two before reburnisning. The sedond time around i use a little cue wax on my finger and burn it in with a paper towell. Seems to work good. Now for lepros i do use the scratch fix furniture markers. Makes em look nice and uniform for your customer