How to acid etch a knife blade

[chuck27p]

Hey guys, I'm new to knife making. I've managed to make a pretty nice handle and I'm doing a svord friction folder. the blade is carbon steel. i'd like to do a nice design on the blade -- i've been thinking about acid etching or patina. Attached is what i'm trying to achieve, I'm just not sure how to do it. It appears to be acid etching. Is there a way to do acid etching with vinegar and nail polish, I find conflicting information online. Anyways, since I'm new to this, I'd love some advice or to be pointed in the right direction. Thanks!

 

[Fred.Rowe]

Chuck,

Mustard, whole onion are both used to patina steel. Using a paste or semi solid like onion with a nail polish resist is preferable. Ferric Chloride and other liquid acids have a tendency to "curl" the edge of the nail polish resist. If a blade has been hardened only part way up the blade [differential hardening] the hardened area will etch faster than the softer steel. I've used melted wax to cover the entire blade surface and then remove the areas where I want it to etch. There are numerous techniques as well as etchants to try. Do a little experimenting and see what works best for you.

This is a mustard etched blade.

Good luck and post your results, Fred