Steel bluing

rte66 · Post by **rte66** » Thu Apr 17, 2014 6:21 pm

It appears that a lot of parts (like the strip sander platens) were at one time blued. Does anyone have experience with the process and what it takes to hold corrosion at bay after bluing? Do those of you who do restoration bother to renew the bluing, or just preserve the metal some other way? Is it as hazardous a process as I have been led to believe? Any preferences as to which process/ product?

Thanks

nuhobby · Post by **nuhobby** » Thu Apr 17, 2014 6:26 pm

I have touched up some hardened-steel Shopsmith parts with a cold bluing compound from Birchwood Casey. I was satisfied enough given it wasn't too hard to do. Keep those parts waxed and they should stay fairly pretty.

dstensland · Post by **dstensland** » Thu Apr 17, 2014 7:53 pm

Last year I used some of that Birchwood Casey cold bluing stuff to fix up a Shopsmith riving knife assembly that was inadvertently de-blued while dunked in Evapo-Rust. In the end I was happy with the outcome. The riving knife was well-derusted and almost as good as new. I wasn't doing a showcase restoration but the Birchwood Casey did work better than I had expected.

I also de-blued/re-blued a saw arbor but skipped the waxing. Little bits of surface rust appeared a few months later, so nubobby's wax suggestion is a good one for extra protection.

"Wild Bad Bob" · Post by **"Wild Bad Bob"** » Fri Apr 18, 2014 9:50 am

There is 2 types of bluing, hot and cold. The hot is the hazardious one do to stronger/hazardous fumes, in tanks of solution, but does a better job of a bluing coating. Cold bluing is the Birchwood Casey type is a wipe on, and usually takes a few more wipe on coatings to get a finished product.

JPG · Post by **JPG** » Fri Apr 18, 2014 11:23 am

The black oxide is not blueing, but involves heat treating. Think of the 'cold process' as dying.

Quite adequate for intended purpose.

dusty · Post by **dusty** » Fri Apr 18, 2014 12:00 pm

[quote="JPG40504"]The black oxide is not blueing, but involves heat treating. Think of the 'cold process' as dying.

Quite adequate for intended purpose.]

This appears to be a matter of words.

Re: First sentenced in this link.

"Wild Bad Bob" · Post by **"Wild Bad Bob"** » Fri Apr 18, 2014 8:27 pm

Like rust, bluing is a form of an oxidated protective coating caused by a chemical reaction with the steel/iron. Even though some solutions are heated, it is not the heat in the "bluing process" that causes the color change, it is the chemical reaction causing a colored protective coating.
Now case hardening with "heat" causes a color change in the steel, which can vary based on the steel composition, amount of heat and medium it is quelched in.