JW, Permalyn is a different cat. In fact within 24 hrs. a subsequent coat will dissolve the coat underneath rendering little gain in build up. Seal heavily, then wait longer than 24 hrs. before 2nd. coat. I mean, I my go thru a third of the can sealing. Back and forth. Only when it gets sticky do i stop the first coat. 90% of what goes in the stock, goes in on the first coat. Everything after that is for appearance. It seems to accept itself or Linseed oil varnishes just fine. I've been using it for 25+ yrs. Urethanes aren't really good for anything but interior applications, though they can be made very hard for floors.