I am refinishing a set of kitchen chairs and decided to apply polyurethane as a top coat. The problem I'm having is obtaining a smooth streak-less finish on the seat and back. I have been using a china bristle brush and have applied three coats so far using 320 grit paper in between coats. In trying to obtain a smooth appearance, I have been going over the surface many times in an attempt to "smooth" the brush marks. I am applying a thin coat in an attempt to avoid heavy streaks. Could I be brushing too much? I have heard that a foam brush may be better suited. Any ideas or suggestions would be appreciated. Thanks in advance

 

Frank, it may be a combination of you defeating the self-leveling properties of the finish by applying too thin a coat, and by over-working the finish as it dries. For a really high gloss finish, spraying is the best method of application. Let the final coat dry for 2-3 days. Rub 2 pieces of extra-fine sandpaper against each other until they're smooth, then go over the surface ever so lightly with the grain of the wood, and clean up with a tack rag.

 

I agree with Refinishing Pete on his analysis of the smoothness problem - polyurethane, like varnish, gets professively worse the more its brushed out.

The gentleman who taught me how to apply a varnish finish (we won't say how long ago) gave me one great piece of advice. If your brush goes over the same spot more than 3 times, you're overbrushing.

Lay it on with one stroke; spread it out with one stroke; tip it off and leave it alone.

In case tipping a finish off is phrase unfamiliar to you - here's an explanation.

Polyurethane (and varnish) tends to bubble when applied. On the last stroke over a given area, you hold the brush about 5 degrees off vertical, leaning in the direction you're going. The bristles just barely touch the surface of the finish - breaking up the bubbles and smoothing the finish.

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George T.