Hi Jim, Didn't we do this once already, or am I hallucinating again? Too much ding, ding, ding lately to remember ANYTHING. <G> Anyway, it's because of something you already know. Wood is not homogeneous. The growth season that produced that particular layer (annular ring) differed from the average enough to produce a layer of wood with a different density and humidity response curve than the surrounding wood (earlier and later growth). The bridge being glued across the grain is incidental. It isn't a propagation thing. The wood layer that failed, failed on both sides of the bridge by the same process at roughly the same time. That's also how a soundboard can have cracks and still hold a viable crown. If soundboards could be made from trees grown in ideal conditions, with uniform temperature and rainfall season after season, maybe we could be seeing hundred year old plus boards without cracks. Oh oh! What have I done? Wait! I didn't mean that! I take it back! NOOOOOoooooo...... Ron At 12:15 PM 9/14/97 -0400, you wrote: >List; > I'm in the process of shimming a soundboard and the following question >comes from that work. > Why, or how, does a split/crack appear in the same grain line on both sides >of a bridge if the bridge is tightly glued down to the board? I suppose this >'could be' a follow on of the "creeping" thread on glues. I don't know the >answer to this question, just wondering....... >Jim Bryant (FL) > Ron Nossaman
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