What should I use to sign black foam core?

NikonsandVstroms

I'm showing standout mounted prints from bay photo that use a base of black foam core. My black micron obviously won't show up so I was wondering what would be the best type of pen to use? Or does pencil shows up well?

Earache

I have used an art pen(s) that comes in a silver or gold color with a slightly metallic effect - shows-up very well on any color surface because it's more of a paint than an ink.
I don't know the name off-hand because I don't have one in front of me, but they are available at any art supply store or bigger office supply.
They have an internal shaker-ball to agitate and mix the ink/paint, and it takes a bit of practice to get the line you want.
The two drawbacks are, a somewhat large tip and so, line size... and they tend to dry-out if you don't use them regularly - that's why I don't have one at the moment...

NikonsandVstroms

That really thick line is something I'd like to avoid. For the prints I use a .25mm pen. I saw that sharpie has metallic silver pens that can write on dark material so I'm thinking of using that. The tip is still relatively thick but less so than the paint pens I've been finding.

moose135

I have a couple of silver Sharpies, I think they may have one with a thinner tip, but they're at home and I'm still up in NY until next week...

NikonsandVstroms

The silver sharpie worked perfectly.