>They are probably 4 years old.
I've had them that were 30 years old...
> It did come from a brood chamber. It also has turned really hard.
And that is a bad thing?
>The Q had gotten to where she didn't like to lay in it. Pulled it out and she began laying like a champ in the new rack.
OK. Just scrape it down and give it back.
>So, how do I expose this and other plastic foundation to wax moths if I'm trying to keep hives and storage areas clear of them?
there's a dilemma. Reality is they are all getting exposed to them. But I'd settle for just scraping them off if that's what you want to do or dip them briefly in boiling water to get the comb to fall off (don't heat too much or the plastic will warp).