Paint markers?

I've been seeing/reading some breeders use a small bit of paint marker on their snakes when they breed them to tell two apart that look very similar. Has anyone done this? All I can find are oil based markers, would those be bad for scales? I'm thinking of ball pythons specifically, I've got some hets that look near identical. Thanks!

I've never had a male and female I couldn't tell apart however I suppose it is possible for them to seem similar. What you can do is take a picture of the top of the head and neck. The pattern there usually differs enough to identify a specific animal unless it is a BEL. I wouldn't rely on anything that is "painted" on the snake, even if you could find something that works safely it is likely to come off.

The dorsal stripe is their finger print.
If they are that close together then do on their feeding cards (..-~) or whatever resembles their markings.