I was recently digging through some old boxes looking for old LEGO bricks I had as a kid. In two of the boxes I found old double A batteries that had busted (the boxes were in a building that has got hot during the summer). Well in the corners of the plastic boxes I found brown dust. I'm thinking this might be lead dioxide from the exploded batteries. I also burnt my hand accidentally touching one of the exploded batteries. Am I right in this assumption? Is there a way to clean the bricks by soaking them in water with a chemical (baking soda)?

Any advice would be appreciated I just don't won't to lose these LEGO bricks.

1 Answer 1


It's very unlikely to be lead, smaller batteries don't use it. If the batteries were old rechargables they might contain cadmium (NiCd batteries). Most likely what you had was a disposable AA battery which will be an alkaline cell. As you'd guess, you can neutralise that with acid. But not a strong acid - you don't want to dissolve away the metal parts of the Lego battery box!

There are a few how-to guides on the web that I found, like this one and this one They all suggest either lemon juice or vinegar as the acid, and focus mostly on

  1. don't touch the battery gunk with your hands (or eyes!)
  2. wash it before scrubbing it as well as after
  3. use something disposable to scrub it with
  4. and don't touch it with your hands

Personally I'd put on rubber gloves, dump it into a plastic bucket full of water (always put chemicals into water, never water onto chemicals), swish it around and see whether the mess washes off. That's easy and you'll end up doing it anyway, so starting there might save you even having to find the vinegar bottle.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.