Rough Finishes with open Pore Woods

Why open pore woods seem to produce rough finishes - March 17, 2000

by WOODWEB's Finishing Team:
John Buries and Bob Niemeyer

Q. What causes open pore wood substrates to feel rough after final finish? We apply one double pass of catalyzed sealer and sand with 220 grit paper. Our second coat (also a double pass) is a high solids Conversion Varnish.

A. John Buries responds: All coatings have surface tension. You may notice, when you spray a heavy coat of clear, that it builds up around the edges of your piece (picture framing or fat edge). When you spray an open pore wood such as oak or mahogany, this again occurs around the edges of all the pores. Even though you have a lot of build, the final coat feels rough.

Reduce the amount of film applied per coat. Sometimes adding a small amount of the proper reducer allows you to spray a lighter coat, still maintaining flow properties. In most cases the smooth look and feel far outweigh the slight reduction in build.