Dean writes: << Moisture causes CA glue to set up. I think what is happening is that doped blocks have more residual moisture causing the CA to set up faster, giving higher torque readings in a shorter time period. << The moisture required to form the acid which breaks the bonds in the CA solution is measured in a few parts per million. Any block will have sufficient moisture to cause the bonding action. >>My theory is the CA swells the wood and this is what causes the increased torque. (any actual bond to the pin is broken the first time it is turned) The cellular structure acts as a matrix that the CA supports after it sets. >> Perhaps, however, I had always attributed the CA action in blocks to the increase of surface area,(at the molecular level) of the friction surface. I don't think there is much swelling action going on in the block. To test, use a micrometer on a hammer shank, then wet the shank with CA. After it dries, remeasure and I think you will find there is virtually no difference in dimension. REgards, Ed Foote RPT http://www.uk-piano.org/edfoote/index.html www.uk-piano.org/edfoote/well_tempered_piano.html
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