Bowed Glue Up

Hi All,

Question: I made a box of Poplar about 2 weeks ago, but I never got around to putting a finish on it.

I left for a business trip earlier this week and the box was fine; however, I just got back and found the lid quite bowed. After reading up on what could have gone wrong, I found that I may have over tightened the clamps. I also probably didn’t give the wood enough time to adjust to my shop, but I don’t suspect that is the problem.

My question is: As I was doing the glue up, the panel did want to bow, however, I put a brick on the center to keep it flat; and it was flat for at least a week thereafter.

Any ideas as to why it took over a week to bow ? Also, I have a lot of pressure on it right now to flatten it, but I suspect it will not work or may snap the joint ???