I've been laid up for a year with a broken ankle. I finally got out into the shop this week.
I had 3/4th of a gallon of Baitplastics #292 med. hard that had been sitting all that time. It had separated to clear on the top half, and thick white on the bottom half.
I stirred it for two minutes, and it totally remixed like it was new.
I'll be pouring again next week, adding some heat stabilized and salt like I always do, and I'll report back how it behaves.