I'm getting ready to pick and process my Olives from my little tree and so was googling for additional info to what calpat sent me. I "tripped" across a State of California site that gave this warning:

"Once opened, store unused California Ripe Olives in their original brine in the open can and cover with plastic wrap to allow oxygen to permeate. Do not store California Ripe Olives in an airtight container as harmful toxins may develop. If the original brine has been discarded, replace with a solution of one cup of water and 1/2 teaspoon salt in order to keep the olives wet and free from external odors. Partially used cans of California Ripe Olives may be held in the refrigerator for up to ten days. "

I think I have at least one opened but tightly re-sealed jar of olives in the 'fridge that is well over 10 days old. And, I never leave anything in a tin can.... or is that just another old-wives' tale? Since this is what I've always done, as did my mother, I'm surprised we never got sick from eating re-sealed olives.