Which Thompson WaterSeal product was it? Water-based or oil/solvent-based? Please post the product name, I'll run this by Thompson. I would be a bit worried about water-based one breaking down if frozen but never had it happened to me before, so I'd like the manufacturer to confirm.
I have a can of Thompson's wood sealer for the deck which was frozen over the winter. Can the product still be used?
Thompson's Waterseal response was:
If possible, can you send us the 12-digit UPC? If you are in the U.S., it should start with "032053", followed by 6 more numbers. Some formulas are more susceptible to freeze damage. Separation or congealing would be a sign not to use the product.
By the way, do you see any visible separation? Should be easy to spot if you just swirl a mixing stick in the can - do you see any streaks?