Messages

Subject:
good point and answering a question

Bill Tindall, E.Tn.
What is necessary is pounds per square inch. Hence, if the thickness of a panel is doubled the necessary total clamp pressure is doubled.

As you point out a disadvantage of steel bars or pipes is corrosion by the glue squeeze out. The dissolved iron reacts with the lignin in the wood and colors it black, but only to a small depth. Furniture factories don't need to worry about it because they glue up panels from thick lumber. When they plane to thickness the black is removed. However, we often glue panels from finished size lumber and this staining is a problem that must be avoided. Coated steel and aluminum bars do not corrode which can be an advantage, especially is case assembly where isolating the clamp bar could be inconvenient.

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