If I can have my say here for what it's worth. Check out the photo of my truck's
dashboard, I sprayed it with durathane k , in the photo it looks like there's like
white powder on it, this is from smoothing it with fine paper, It's still got to get
the final coat. I dit about eight coats already, sanding in-between coats.
Yes you can-not apply thinners based products over wood stainers or varnishes,
the reason is that they contain oil and are minneral based, that is why you will
use terpentine to thin them with.
And seal the wood right around even inside holes if there are any.