2ndly if they do NOT have a layer of wax then get the heat on and melt some and paint them with it. Bare plastic is highly unattractive to the bees and may under some conditions push them in to swarm mode by reason of lack of space. Yes you think you have given them ample but they may just not see it in that light...LOL
I've used plastic foundation in wooden frames ever since they first came
out, and they are great - for honey supers.
I would never ever ever use them in a brood chamber.
Pre-wired wax in brood frames gets drawn so much faster.
The black versions are intended to allow you to see eggs better,
but see above - you don't want them in your brood chamber.
I've never have a wooden frame with plastic foundation "blow out"
on me in the extractor, and we run some very high RPMs to get
as much honey out of every super as we can. Back before
plastic foundation, I'd often have one (of 3) extractors "down" with
a blown-out comb jamming the works up. After plastic was deployed,
one was being loaded, one spun, and one unloaded all day and all
night without a hitch for the entire 3-time a year ordeal.