I am in the middle of refinishing an old set of french doors. In working with the vertical surfaces I screwed up and applied the second varathane coat too thickly, resulting in some runs and sags. Is there a fix for my poor application, or am I doomed to stripping and starting over? (Ken)

A:  I'm with Todd on this one. Good luck. Poly is notoriously hard to get "right." One of the most common "issues" (mistakes?) imho is the failure to thin it properly. When left thick it almost always droops and leaves bumps. You may get best results by using it "wipe-on" style: try thinning 50% and then wipe it on with a cloth. It will take quite a few more coats to provide coverage, but it will probably come out looking better.
If you don't want to wipe it on, at least thin it by 15% or so and then try brushing it on with a high-quality natural bristle brush. Don't overwork it. Try to remove hairs and dust before it dries. After the first coat has dried, if you want you can sand it lightly with #400 paper to remove dust bumps and other imperfections, then apply another coat. Even to brush on you need to thin the stuff that comes from the factory. One of the very few cases where you get more than you pay for. Seems that the thinner in poly is what causes the nasty pollutants, so to get their numbers down, they put in less thinner. For brushing, add about 15% thinner by volume. You can use Mineral Spirits, Turpentine or Naphtha. The naphtha will flash off quicker and there-fore dry quicker so you can get to your next coat sooner.

For wiping mix 50/50 with thinner. Again I like using the Naphtha since it allows you to get the next coat on sooner. You will need to apply twice as many coats to get the same coverage, but it is not really necessay to sand between coats except to remove imperfections. (R. Lancon)
A:  You could wait until it firmly sets, which for varathane, could be a week or two, then sand and recoat. I hate stripping - that's why I would sand and try again.
(T.Burch)