I am toying with the idea of laminating spruce ribs with Titebond and providing clamping pressure with the vacuum bagging technique. Of concern to me is the relatively low pressure attainable with vacuum bagging. With a perfect vacuum, you will only get atmospheric pressure - 14.7 psi. Del Fandrich has reported good bonding with 40 to 50 psi and the Titebond web site recommends over 100 psi. Clearly, less than 15 psi is reason for concern. However, Ron Overs reports that he is using vacuum bagging to manufacture his laminated soundboard panels. I presume atmospheric pressure on the east coast of Australia is about the same here in Florida. How does one reason all this out - vacuum bag a rib and then watch it for 75 years? Terry Farrell
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