Lens element paint?

What is that matte paint used on the edges of old lens elements? I have a couple that could use significant touching up. Thanks!

Probably some carbon black based paint. I would suggest Testor's flat black model paint as a substitute. It should adhere to glass easily. Use as little as you can. Be careful with cemented doublets as the solvent in the paint could cause problems. I doubt this as it dries very fast, but one never knows.

I use a gloss black Tamiya lacquer for element edges. Frisket and masking tape to cover the glass not to be painted. Two or three very light coats misted on the lens works fine.
You should degrease the surface to be painted using rubbing alcohol or ammonia applied with a cotton ball or lens tissue thoroughly wrung out.
Nice thing about the Tamiya paint is that it's a lot easier to get a thin coat than with enamel.

Testor's flat black paint works very well, and careful application with a small brush provides the most control. I use a small plastic suction cup about half an inch in diameter to hold the glass element while working on it. (These suction cups are available in hardware stores as well as 99-cent stores, and originally come outfitted with wire hooks for household use. A handful costs a dollar or so.)

Try to apply the thinnest coat possible the first time around, and even out the coating by the second coat. If the lens elements have large patches where the original blacking has come off, I would suggest coating those areas first then allowing the paint to dry. Then you can use the second coat to give the circumference of the lens element an even coat.

I hope this is helpful.

I read an article somewhere many years ago, about kodak actually using some derivitave of india ink on their elements, as this was years ago, I cannot cite where I saw it, the flat black model paint seems to works okay...