Q: Is polyurethane earth-friendly?
Figaro Subrosa: Perhaps "friendly" is too strong a word, but the earth did accept polyurethane's "friend request" on
Facebook. Joking aside, once it is dry, polyurethane is inert and therefore landfill safe. However, in its liquid form, it may contain both solvents that should not get into the water table and solvents that can be ozone generators. Looked at it that way, the answer would have to be no, but to put it in perspective, most hobby woodworkers do more damage to the environment driving their car for one month than they do with all the finishing materials they use in a lifetime.
(Seriously, though, you can check out the Woodworker's Journal Facebook page by
clicking here)
Q: What is the difference between wipe-on polyurethane and the brush-on? Can the brush-on also be wiped on?
Greg Williams: Wipe-on finishes are designed to be wiped on thin and without concern for flow, since the excess is usually wiped off. If they are wiped on thickly, or brushed on, they will show streaks and ridges. Brush-on varnishes remain wet and liquid long enough to flow out more smoothly, and thus don't show brush marks as badly.
Michael Dresdner: To sum up, most brush-on oil-based finishes can be wiped on and wiped off, but most wipe-on finishes cannot be successfully brushed on.
Q: Can polyurethane be used over waterbased fillers such as Wunderfil?
Michael Dresdner: Yes, absolutely.
Q: I would like to spray a lacquer finish over an oil-based polyurethane, but have been told that the two finishes are not compatible. Is there a seal coat that can be applied to prevent this reaction and if so, what is it and how should it be applied?
Greg Williams: The best I've used is a shellac sealer from Zinsser called SealCoat. It can be applied by brush, rag or spray. Test the whole procedure in an out-of-the-way place before proceeding.
Kevin Hancock: Why do you want to do this? Polyurethane is a more durable coating. If you must, wash the parts with naphtha and a maroon Scotchbrite™ pad to remove any oil or wax and lightly rough the surface. Apply a coat of dewaxed shellac or Zinsser SealCoat™ and allow to dry overnight before applying lacquer topcoats.
Richard Jones: Use a dewaxed shellac as a barrier, and then spray your lacquer.