[KQ2eZPackers]

I need to prepare a mixture of 2 parts nitric acid and 1 part acetic acid for electrolytic etching of a stainless steel sample. I don't know how to safely mix these two chemicals together, and am inexperienced with dealing with acids. What is the best way to make this etchant?

[chenbeier]

Take a magnetic stirrrer and put a beaker glass on it. Add the acetic acid first and then add during stirring the nitric.

[Arkcon]

Take a magnetic stirrrer and put a beaker glass on it. Add the acetic acid first and then add during stirring the nitric.

That's the answer.  For acids of moderate strength, you may get some heating of the solution, but there shouldn't be a problem if you work slowly, and magnetic stirring keeps a hand free.

If you're talking about concentrated acids, this could be a disaster in the making, or at least, a major problem of a runaway reaction.  So it should be in a chemical hood at the very least.

You left those specifics off, so you can't blame our group if the help we offer is incomplete, one way or another.  Can you tell us the specific recipe?  For electrolytic etching there are many options -- NaOH, or oxalic acid are other options.

[Corribus]

Note that nitric acid (an oxidizer) is not chemically compatible with acetic acid. They will react, possibly vigorously, generating toxic gas and heat. Even if you do it safely (e.g., in a fume hood), this will constitute a waste disposal hazard.

[billnotgatez]

@KQ2eZPackers

Could you post a link to your etchant recipe?

[wildfyr]

This seems like a bad idea. glacial Acetic acid and nitric acid are specifically not supposed to be stored together because they will violently react.