I am using Pettit EasyPoxy 1 part urethane paint to redo the window frames on my vessel (carefully following their instructions). After using the paint for a session, I back fill the can with notrogen to prevent skinning. When the can was half full, I noticed, upon openning the can, that, overnight, the paint had partially solidified, attaining the consistency of cottage cheese throughout. I called Pettit's tech service and they were less than heplful, declaring that they had no idea what happened. Do anyone have a clue as to the problem?