Sometimes this works for me, if the pot isn't too big, push a bamboo cane through the holes of the bottom pot if you can, stand on the cane on both sides of the pot, pull up on the rim of the top pot. With 1 gallon pots I have got them apart by squeezing the bottom pot between my feet and tugging on the rim of the top pot.

A......

I have used the tines of a spading fork like A uses the bamboo. Also have tapped with a hammer on the rim. Rolled the stack back and forth, pushing down to break the seal. And other methods as well. Lots of cussing, too.

Yes silver creek, lots of cussing, I don't know how much it helps but it sure vents my frustration.

A......