Why do jars crack sometimes?
I was making dilly cabbage and while the water bath was boiling, I poured the near-boiling solution into the jars of cabbage. I took my time to clean the jars, add extra cabbage, top off the jars, etc. About 10 minutes elapsed before I put the jars slowly into the boiling bath. When I did, the bottoms cracked and fell off into the bath. I would guess there was a temperature difference of 212 vs. 175 between the bath and the soultion. Why did the canning jars crack? Now I'm weary of putting any temp jar into a boiling canner or bath. What is a safe differnce in temp?