>
> Al:
> Formic acid is an organic acid and has little or no effect on metals.  Just
> be cause of the word "acid", too many people think of burn, destruction, etc.
>  After all, carbonated water is carbonic ACID.
>

I'm sorry, but as a metallurgist, I can categorically state that the above
is not true. Organic acids tend to be weaker acids than "mineral" acids
like sulfuric and hydrochloric acids, but they can still be *very*
corrosive.  What makes them corrosive are:

1) The availability of free H3O+ ions, which dissolve any oxides that
may be coating and protecting the metal surface, and

2) The increased conductivity of the solutions, which opens you up
to galvanic corrosion.

If the organic acid also makes a soluble salt with the metal (and
iron formate is, in fact, a soluble salt), the metal will corrode
in the acid even faster.

So, in fact, there are excellent reasons to expect formic acid to corrode
iron in the hive, and I have seen reports that this is a real problem.

Tim Eisele
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