sam530•8d ago

I tried vinegar vs. citric acid for cleaning calcite off a fossil

Last week I had a chunk of limestone with a small brachiopod fossil, and the calcite crust was really thick. I tried soaking a piece in white vinegar for 24 hours, like I always do, but it made the fossil itself look kind of chalky and weak. Then I mixed up a 10% citric acid solution and tried it on another piece from the same rock for just 4 hours, and it ate away the crust perfectly without hurting the fossil details. The citric acid was way more controlled. Has anyone else switched from vinegar to something else for cleaning finds?

3 comments

3 Comments

the_anna7d ago

So Julia843, did your hawk-watching method ever make you miss your favorite show?

linda_butler288d ago

That controlled action with citric acid is exactly why I switched. Vinegar can get too aggressive and damage the matrix. A mild citric acid bath gives me way better results for delicate stuff.

julia8438d ago

Honestly, I've had the opposite happen with citric acid being too slow. For really thick calcite, a short soak in stronger vinegar, like 20% for just an hour with constant checking, works better for me. It stops it from getting that chalky feel. Tbh it's all about watching it like a hawk and pulling it the second the crust is gone.

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