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Acid Concentrations in slow-rust formula

 

I just happened to find this site, and I'm pleased for the first time ever to actually find a recipe on slow-rust bluing solution. I tried a cold bluing formula developed at the turn of the century (that is, the former), but it was a poor result, because I used one that was based on a copper nitrate ⇦ this on eBay or Amazon [affil links] solution. This formula seemingly works only for small repairs, and is quite difficult to master, which I learned the sad way. In addition, the chemicals are fatal, both fumeurs when the copper nitrate is extracted and the finished product. I still need to discard of it in a environmentally sound way, but I'm working on that.

Hot caustic bluing is for pros only, and is risky business as well. Think about it for a minute, cyanide is even used for bluing purposes, or rather, was used, as only very few will ever obtain the necessary permissions in most western countries today. All in all, amateurs are left with the slow-rust bluing which is probably also the procedure which provides the most wear and tear resistant result, according to e.g. John E. Traister: Lock, Stock and Barrel.

Anyway, this detour was only intended for those who ever is to be perhaps slightly interested in hearing what a complete amateur has to say on these matters, because foremost I have a question to all these people who are so kind to share their knowledge and experience with the rest of us who only intend to do small restoration projects and probably only a few times in a lifetime.

My question is addressed to Mr David Fiola (letter 982), who admittedly, some time ago, passed his slow-rust formula on to this site. I simply do not find the concentrations of the acids that he uses. It seems to me to be as important as the amounts that he suggests for his recipe. Does anyone know the 'correct' concentrations?

P.S. Please forgive me my poor English, I'm living in Scandinavia, so it takes me some time to spell just in order to make me understandable.

Anders Nielsen
- Denmark

Please: I need a real good working slow rust bluing formula. I'll be really grateful if some kind hearted fellow can give me such a formula.

Nicolas Romano
- Buenos Aires, Argentina

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Please see letter 982, Mr. Romano, which is a long discussion of that and related topics.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
 

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Here is the famous blueing formula (commonly known as Neidner's formula):

Nitric Acid (about 70% concentration)- 2 1/2 oz. Hydrochloric Acid(about 30% concentration)- 2 oz.
Iron Nails (or iron filings [affil links] )- 1 oz.
Distilled Water 30 oz.

Dissolve iron in acid, then add mixture to water.

Roberto Barcala
- Miami, Florida
March 19, 2008