To make sure the ink doesn't rub off, I sprayed the beads with PYM II (Preserve Your Memories II) that I read about online a year or so ago. It was advertised as safe for polymer and I did a test. Nearly a year later the beads are still perfectly good. My only concern now is if any reaction might happen between the marker and the spray so I'll let these sit for a few months to see what happens.
The only problem I had was in one spot on the coral blue beads where I may have gotten the surface too wet with spray...the marker blurred a bit. You can't see it in the photo below, and it doesn't look terrible, but it's something to watch out for next time.
|Purple Pod Linework|
|Khaki Olive Linework|
|Coral Blue Linework|