I hope you save some pieces of this soundboard and try to duplicate the varnish bubbles in your shop. Laws of Physics would dictate that the top of the board could never get hotter than the bottom when heated rapidly from below, yet the finish on the bottom isn't bubbled. When wood is heated rapidly, such as when burning, water is forced away from the heat. Maybe steam caused the bubbled finish? Is the finish on the top different than that on the bottom? Regarding the possible property changes of the wood, that depends on time and temperature. Commercial heat treating of softwoods is done in the 220 C range for several hours, and results in decreased bending strength and elasticity, but increased compression strength (think "more brittle"). Note, though, the high temperature (220 C, not F) and long exposure of several hours. The Wood Handbook says permanent changes in elasticity or strength take months of exposure at 115 C to become significant, weeks at 135 C, and days at 155 C. I would bet the temperature of your soundboard didn't get above 100 C (converting water to steam) and only for a couple minutes. I doubt there was any chemical or physical change to the wood. Greg Graham
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