"stuck" plastic 5 gallon pails

Hello,
Somebody else has got to have had this problem and I am seeking a cure. I have about 2 dozen 5 gallon buckets all nested together in one single stack.

Yesterday I tried to get the topmost bucket separated from the rest for a project and it was stuck so tight that I could not remove it. They all seemed to have "welded" themselves together over time. There must be some way to break this bond that has developed and nobody here seems to have an answer that won't end up in destroying some of the buckets.

This site has been very handy in terms of information on gardening, and I would really appreciate a correct method of separating these buckets without undue aggravation.

Thanks in advance for your help in this matter.

Geneso