The Ferric Chloride Etch–An “Instant” Patina?

Often, outdoorsmen prefer the well-worn, unobtrusive look of oxidized steel, rather than a shiny finish. For example, bluing on firearms. Back in the old days, they sometimes called it “browning.” Basically, it is the controlled use of rust for beneficial purposes. This rust is induced with acid, which can range from vinegar, to nitric acid, to fruit juice, to a variety of other things. Then, it is carefully managed until a protective, aesthetically pleasing finish is developed.
Another benefit of this etch is that it can show the direction of grain in the steel, and show the difference in hardening or tempering zones. The hamon line on Japanese swords, and Damascus steel, are two examples where an oxidative etch is used for function and beauty.
Here you can see an example of the FeCl etch on the lower knife:
Bowie knives, contrast between a satin finish and ferric chloride etch patina
This finish needs to be maintained. Just keep the blade clean, and give it a light film of oil to prevent unwanted rust.
Please note: this etch is only applicable to non-stainless steels.


About christophersknifeblog

I am a knifemaker and dealer, and live a very diversified life in the mountains of central Idaho. I love nature, agriculture, and homesteading. My knifemaking motto and advertising slogan is, "Knives Built for the Bush." I intend them to be efficient, durable, comfortable, functional, graceful equipment for life's challenges and opportunities. My website is Please visit!
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2 Responses to The Ferric Chloride Etch–An “Instant” Patina?

  1. Pingback: Filework | Christopher's Knife Blog

  2. Pingback: From Junk to Jewel | Christopher's Knife Blog

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