Effects of Rust Bluing on Damascus and Twist Barrels

[Dean Romig]

Yup, hot blueing is an entirely different process... be careful.

[J. A. EARLY]

Bruce,

I have never had the chance to meet you and have never been to Omaha, but would like to do both some day. I was referring strictly to barrels that have been rust blued and was referring to the acid working its way into the Damascus or twist, especially if there is a pitted/rusty area on the barrels and who knows what exists under the ribs.

I know the soda solution after the bluing should neutralize the acids and the water displacing oils will finalize the process for the recesses, if that was done. Many people associate a vent hole drilled in the bottom rib near the forearm lug with hot bluing but it is also done on rust bluing jobs so the soda solution and water displacing oils can be sure to get in there. So my question is just about the ones that have the rust bluing. I was rust bluing fluid steel barrels without venting them after talking to many people who said that it was unnecessary, but then one of the best gunsmiths I know said he had changed his mind and it would be wise to vent all of them, as there was no such thing as a perfect solder job after one hundred years, and without doing so all of the acid and water could not be displaced. I guess my main concern with the rust bluing on composite barrels is in pits and rust, some of which can/could not be seen. But as Dean pointed out, refinishing them to the original Damascus or twist pattern will mean a solution that is just as corrosive and more so. I guess the moral is, if the Damascus or twist has ever been refinished, there is always a chance of penetration of the solutions into the composite metal. That is the basis of my concern when I see them.

[Autumn Daze]

Jerry, Years ago I bought a BH grade damascus gun that the barrels had been rust blued. I sent them to Oscar Gaddy and he refinished them. In fact this set of barrels was one of the last few that the good Dr. did.He explained to me that it was a good thing they were rust blued and not hot blued because hot bluing almost always results in some mechanical problems. When I got them back Dr. Gaddy sent me a letter with the barrels explaining that this was the finest damascus pattern he had ever seen on a Parker. I will post a couple of pictures later.

[Parker Bachelder (Brad's Profile)]

Blackening of steel is not done with Acid based solutions. Bluing or blackening in all forms is an accelerated rusting or oxidation and subsequent staining. The most common types of bluing are as follows:
Black Oxide Bluing "hot bluing"
Corrosive solids consisting of sodium hydroxide and sodium nitrite, mixed with not acidic chemicals for penetration and color. Run at 292 degrees.
Slow Rust Bluing
Non acidic, non toxic rusting agents. Heated to 150 degrees, applied, boiled at 212 degrees, carded and repeated.
Damascus Finishing
Non acidic, non toxic rusting agents. Heated to 100 degrees, applied, steamed at 100 degrees, carded and repeated. Boiled once in a mordant bath at 212 degrees.

Hot bluing of damascus or any soldered barrels will immediately or eventually destroy a set of barrels. The temperature and caustic solutions will attack the lead in the solder and break it down, destroying the bond.
I have not seen any evidence of the caustic affecting the welds in a Damascus pattern.
Hot blued barrels need to be completely resoldered prior to finishing.
Determining hot blued soldered barrels is fairly easy. They usually will not "ring". Exposed solder generally will appear white and crystalized.
Damascus barrels blackened by the "slow rust" process can readily be refinished to black and white, with the correct process.
The Damascus finishing process is the least invasive of all types of metal finishing. Using the mildest chemicals and lowest conversion temperatures. The patterns are a natural conversion of the steel and iron. The contrast, depth, color and patina, are more from technique rather than chemically induced.

Brad