by wannabefree » Sun Mar 01, 2009 9:50 pm
Humidity and wood moisture content play a big role, which is why I mention I live in AZ. Here the wood is so dry (maybe 4% MC) it literally sucks the moisture out of the glue. Glue sets hard enough to work in half an hour. Often to extend working time I wet the edges I'm glueing and mix a little water in the glue. Like I said, clamps are off in half an hour and I'm working the piece unless I'm going to put a lot of stress on it. There is one condition where I do allow 24 hour dry time -- when edge glueing boards. If you surface edge glued material too soon you end up with gullies at the glue line because the wood swelled when it soaked up the mositure from the glue, then you surfaced it, then it shrank.
So the answer is: it depends. 2-4 hours clamp time is more than sufficient under most conditions, though. If in doubt, check the squeezeout. If it's stiff and plastic-like and can be scraped off with a blade without smearing, it's hard enough to take off the clamps. In fact, when the squeezeout is at this state it's the ideal time to remove it with a scraper.
In anything at all, perfection is finally attained not when there is no longer anything to add, but when there is no longer anything to take away.
-- Antoine de Saint-Exupery