Zinsser Sanding Sealer can failure

Actually not an old wives tale but the truth when battery cases were made out of wood and were not sealed as well as modern plastic cased batteries.

And an explanation

Chances are good it was a small puncture from concrete aggregate or something on the floor. If it were pool chemical the entire can bottom outside would have been corroded. (A friend never used his pocket change, but threw it in a plastic bucket to cash in some day. He left me one of his buckets. Turns out it was a rinsed-out pool chlorine tablet bucket. The silver cleaned up OK, but the copper coins were hard to identify - about $100 worth of pennies the banks won't take.) Plastic-bottom paint cans avoid the corrosion problem, but if you stir paint on the cheap as I do with a bent coat hanger chucked into a drill, you have to be --very-- careful. :) Setting the can on a stray screw guarantees a mess - somewhere. BTW- A sealed can cannot pick up water (and subsequently rust) from anywhere. If warm humid air can get in, when it cools, the water condenses (like dew at night). The next day more warm, humid air gets in, etc. If air can't get in, the only condensation possible is from the air in the can when you sealed it. This is a major problem with vented petroleum tanks where feet of water a month have to drained off the bottom.

- J