I got the stazon ink pad and it left a "detectable thickness" on my champion plastic. Is this what Jerm is using or is there something that they use that absorbs into the plastic the way sharpie does?
I understand your concern. I was playing a tournament a while back and one of my card mates noticed I had a glow sticker on the top of one of my discs. He commented that it was illegal—he wouldn't call it but others might.
I wasn't playing in a cash division. I wasn't close to the lead. But I get that it was technically illegal.
I put it away and didn't throw it anymore. Not a big deal, but there is always the potential someone could call it out.
If you can't find ink that will be undetectable and plan on playing sanctioned events, best to avoid that potential.