There is a moisture gradiant in wood. As moisture is added, the wood nearest the surface expands first later soaking into the middle. Initial reaction to moisture will swell the surface wood around the balance holes probably increasing tightness. Later on the middle of the wood gets the moisture and it too expands. When the whole wood key expands so do the holes in it, like stretching a piece of swiss cheese. It takes time for wood to accept moisture and much more time to lose it. -Mike Jorgensen RPT
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