Etching with iron(III)chloride hexahydrate

[kai]

Hello Steve,

Yes, your etching results are certainly fun - keep them coming!

I have read that doing the first neutralization with vinegar converts some chloride ions to a non corrosive form.

No, chloride ions will need to be extensively rinsed off regardless of any intermediate treatment.

The vinegar may help to remove excess iron salts (if you leave it on for too long you'll reduce the contrast of the stain though) and, thus, avoid the yellowish color which is often visible in blades treated with ferric chloride.

I then rinse and neutralize with ammonia, then with a slurry of sodium bicarbonate.

I'm not convinced it is really necessary to do both. Ammonia may have advantages in reaching crevices in pitted/cracked blades but you'll need to rinse such blades extremely carefully anyway. Ammonia chloride residues are moderately acidic while sodium chloride is neutral; this is pretty academic though since you need to work with excess ammonia or sodium bicarbonate, anyway, and both solutions are alkaline.

Once you have neutralized any traces of acid, you really need to rinse away any salts/ions. Deionized water, lots of DI water!

Regards,
Kai