When you have a limited number of clamps and several glue-ups to do, you don't want to leave the parts in the clamps longer than needed. On the other hand, you don't want to remove the parts before the glue has firmly set, risking misaligned or poorly joined workpieces. (Yellow glue sets in approximately 30 minutes at a temperature above 50° F.) Here's a simple method to keep things straight. Mark the starting time of each glue-up with chalk. That way, you'll know when you can safely remove the boards from the clamps, and you can tell which boards were glued up the longest so you can work on them first.