Q. We have a problem with painted pieces of solid wood in cabinets that we send out. They are smooth when we ship them, but a month or so after they are installed in a house, the grain pattern of the wood shows through the painted finish. Comments please.
Answer. I believe you are likely seeing some of the grain being pushed down into the surface of the wood perhaps by a planer knife or more likely a sanding roller with dull sandpaper. So, the cells in the region are "squished," which is a highly technical term!
They would like to return to their original shape, which will cause the natural grain of the wood to project through as unevenness at the surface, following the grain or growth-ring patterns. What helps them spring back is moisture so I expect these problems show up when the owners begin normal living in the kitchen with plenty of short term moisture.
So, sharp sandpaper will help immensely. Also, before final sanding, liquid water sprayed on the surface will cause the squished grain to recover and then final sanding with minimal pressure and sharp paper can smooth it out. Sometimes in softer woods, we can see excessive pressure from hand sanders pop the grain out later.
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