doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Rust Vs. Salt Blue (SxS Reblacken)

Hi all, curious to get your opinions on these two methods of bluing. What are the pros and cons of these if one where to reblacken a set of bbls on a SxS?

Is there really any difference?

Thanks all!

Greg

Greg,
My recollection from Dr Gaddy was that the hot salts started a inter- or intra- granular reaction in the solder (the tin, I think) that progressed over a long period of time, causing it to fail the joint.

So, for a soft soldered sxs barrel set, don't use salt blue. But I have used hot salt blueing on a set of Spanish barrels that were, clearly, brazed.

There are many differences in the two processes and results. My experience seems to suggest that the rust blue holds up better. But that's just a feeling and I have never seen any real test information on that.

rust blue is the only proper finish for soft soldered tubes. As Chuck has mentioned above, in time the solder joints will fail if blacked in a hot salt bath.
Steve

Hi all, I realize that one can't Hot Blue a double, but I saw on one site that "Salt" blue was offered as an option to reblacken O/U's ans SxS's. I'm wondering if this is one in the same as Hot Bluing?

Thanks all!

Greg

Chuck and Steve or correct, and as far as I know Greg there is no such bluing method as "Salt" bluing, other than Hot Bluing through the use of oxidizing salts. The term Salt blue is probably used because the bluing is done with bluing salts, ie, hot bluing, so dont dip em unless they are brazed!

Rust blue is the best finish for a side by side, I would never use salts on any barrels brazed or not, even braized barrels have holes in, I only ever use salts for actions trigger guards etc, I call my barrel finish blacking., my damascus work browning, and the small bits blueing, but why do we say blueing? because the finish is not blue its black?

traditional rust black

Note that the "Hot" "Salt" bluing attacks the solder joint through chemical reaction. It operates normally no higher than 300°F often around 285° which is not hot enough to melt the joint. Nomenclature is often confusing. We sometimes here of hot rust bluing & cold rust bluing. Both are normally subjected to boiling water, but at different times in the process.

Hi all, thaks for all the responses. I think I got my wires mixed up here. I went to the site and read the "fine" print. The Salt is the same as the hot blue (as you have pointed out). The way it was worded led me to believe it was some dofferent method. Oh well shame on me!!!

Thanks again!

Greg

IIRC, one of the last lots of Ithaca NID shotguns had the barrels done at the factory by the 'hot salt' method. Get 'em done and get 'em gone.
That was the reason for a number of 16 and 20ga completed/finished actions /w stocks and the forends being around for a while. The finished guns less the barrels were sold off when Ithaca went under in the late 80's(?).
The barrels were unacceptable as done in the blueing bath and were scrapped, leaving the rest of the guns to go wanting for barrel sets.

I worked for/with a gunsmith in the late 60's/early 70's that assured everyone that he could hot blue double barrel sets. His blueing salts, which he mixed up himself, had a small quantity of an arsenic compound added which he said would protect the soft solder from the damage of the salts. I never did see any come back in with problems, but the damage is not instantainious nor even usually evident months afterwards. It's a slow deterioration of the solder joints. The rib cavity is a prime place for blueing salt 'bloom' to grow from though if the stuff isn't rinsed out completely

He did loose a couple of shop cats to the concoction though. They had the run of the place and as cats will do, jumped up on everything including the blueing room apparatus to walk around. Then the paw cleaning routine and it was curtains rather quickly.

While we are discussing, any process that causes a fine grained, thin film of black oxide to form on the surface of polished steel will appear blue. As the grains grow larger and/or the film thicker, the apparant color will shift from irridesent blue to black. "Heat colors" are formed when polished steel is heated from around 300 F to 700 F (2p, fill in the colors vs temeperatures as my text book is at home, please); a fact important to tempering hardened steel. "Fire blue" is sometimes used on gun parts by heat coloring polished pieces. Another process than can add confusion to coloring is the molten salt process. It is based on salt (NaCl) melting at a temperature that promotes "fire blue." However, it can be held long enough to give a much thicker film than the usual heat colors; Winchester used it extensively. The film is thick enough that it will, in later life, sometimes actually flake (the reason some old Winchesters have bare spots of steel).