Q: We have drawer fronts that now, several months after manufacture and finishing, have grain raising. The rings of the tree are actually raised, forming a corrugated surface. Any ideas?
A: Grain raising that shows up after manufacturing is a result of wood cells that were compressed (or severely squeezed) during machining, coming into contact with moisture (high humidity, water-base finish and so on). The cells that are compressed are usually pushed down by a dull knife. Knives with excessive laud or inadequate clearance, or machines with very slow feed rates are most likely to cause this damage to occur.
However, even excessive pressure from a hand sander (especially with dull sandpaper) can compress surface fibers.
The moisture causes the compressed cells to swell back to their original size, creating a bump in the surface. It is probably impossible to eliminate the moisture regain. So control is achieved by improving machining. Alternately, add moisture to get the grain raising to occur before finishing and then sand it smooth. Improving machining includes sharp knives with proper angles, pressure bars and chip breakers properly set, adequate feed rates, and sharp sandpaper.
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