Metal Bluing at Home. 2 Methods. Linseed Oil vs. Citric Acid
I tried two methods of bluing metal at home.
The first method, bluing with citric acid on my test parts, didn't produce the desired result.
Bluing by heating the metal and then dipping it in linseed oil did produce the desired result. A uniform black film formed on the workpiece.
Both the first and second methods coat the part with a protective oxide film, but bluing with oil is much more attractive.
Both bluing methods can be done at home for virtually no cost.