06-24-2017, 01:27 AM
I in fact committed that exact "sin" a couple of weeks back. I had glued up a small table top (3ft square) from 1.5" cypress.
My shop is unheated, and it's middle of winter here, and expecting a frost overnight I was worried it would be too cold for the glue to cure properly. So I left a little electric oil column heater under the bench, set on low. The glue-up was on a couple of sticks to keep it off the table, but it must have trapped warm air under the panel. Come in next day, and there is a noticeable bow, maybe 1/2" an inch, across the 3 ft panel.
Mutter mutter. Flipped it over and walked away. It evened out by the next day and is fine now.
Now in this case I knew the wood was properly air dried (been in the shed for years), and that I had induced the uneven moisture that caused the panel to temporarily cup. Once the top is in use both sides should be exposed to about the same environment, and a couple of coats of varnish slow any moisture exchange, so the top wont "banana" up just because it gets an hour of sunshine on the top side occasionally.
My shop is unheated, and it's middle of winter here, and expecting a frost overnight I was worried it would be too cold for the glue to cure properly. So I left a little electric oil column heater under the bench, set on low. The glue-up was on a couple of sticks to keep it off the table, but it must have trapped warm air under the panel. Come in next day, and there is a noticeable bow, maybe 1/2" an inch, across the 3 ft panel.
Mutter mutter. Flipped it over and walked away. It evened out by the next day and is fine now.
Now in this case I knew the wood was properly air dried (been in the shed for years), and that I had induced the uneven moisture that caused the panel to temporarily cup. Once the top is in use both sides should be exposed to about the same environment, and a couple of coats of varnish slow any moisture exchange, so the top wont "banana" up just because it gets an hour of sunshine on the top side occasionally.