Wwhat can i use thats permanent on blades? ?

I'm in grooming school right now and I'm labeling everything that's mine and some girl came up with coloring the numbers in on the clipper blades and so my favorite color is purple so I got a paint pen from hobby lobby that was purple and I colored the numbers in and then today I used my clippers and they got hotso I had to use coolant spray to cool them off well then the paint started to bleed.... I was wondering of just regular permanent marker would work or if u knowof somthing that would work and will stay on no matter what it would be great and greatly appreciated if u could help me! Thanks in advance!!