Different techniques on bluing of Colt antique guns?

[r010159]

I have looked at pictures of many fine specimens of Colt antique guns. I have found basically two types of finish. One is a semi-matte black which can be shiny depending how the metal was polished. I also see a stark bluish-grey color on some barrels. Even though probably wood charcoal, bone, and other ingredients are probably involved with both results, there are evidentally two different techniques involved. BTW I find the barrels with the blue color to be very rare.

What do you think makes the difference between the two? The temperature? The length of time at a temperature? I know that if you place low grade steel into a type of crucible, fill it with wood charcoal and powdered bone, and then place an airtight top on, you can end up with bluish colors. I also know that Colt filled a type of cement basin three feet deep with high carbon content materials, heated in a furnace, took the barrel out, carded it, and repeated to get the desired black color. Maybe blue is the color first arrived at in the furnace bluing process? A sort of tempering? So it may be just the time at a temperature of the furnace?

Bob

 

[denster]

I believe you are confusing the process for color case hardening of the frame with the process for bluing.
In any case the difference of color from deep blue black to bluish gray is a function of wear and age.

 

[Hawg]

Colt only used one technique for bluing from the 1840's until production halted during WWII. The actual color was a light blue. After WWII they went to a hot salts process which is a dark blue black.

 

[r010159]

Then why do many Colts in fine condition just have various states of black? I have even seen a museum quality Dragoon that has multiple finishes, including a semi-matte black.

There are definitely also two kinds of case coloring, which I have also seen on museum specimens. One is a type of brownish smokey grey, and the other is bright case colors that can include blue and red. My Baby Dragoon has most of its case colors which is of the smokey grey type.

So there are two different results to be found. I suspect these results can be obtained from the same bluing process. I think there is a difference in technique. This s what I am trying to find out. The only other answer is that the blue barrel fades into black. I have doubts about this.

JMO of course. BTW case hardening is with the use of the crucible followed by quenching in water or oil. The latter part is what is important. I am just going by what I have read.

Bob

 

[Hawg]

The technique is the same. Time and use/storage conditions affect bluing and case colors. I would imagine iron with it's differences in impurities would color differently from piece to piece.

 

[denster]

Hawg is correct that only one bluing process was used. The variations in colors are from wear, age, storage environment and types of oils grease or waxes used on the surface.
The case colors are from the soft steel parts being heated in a crucible in contact with bone, leather and wood charcoal to critical temperature then quenched in an aerated tub of water. The differential cooling of passing through the aerated water fixes the colors. They will never be the same from piece to piece at origin and are also subject to age wear and environment. In addition to and more important than the colors is that a hard surface is imparted to the soft steel maintaining a soft inner core.

 

[r010159]

As far as case hardening goes, here is some information regarding case colors:

"If the carbon is uniform and the quench clean, all you get is a hardened gray surface. The case colors are due to unevenness in the carbon source, as caused by different size bits and pieces of wood, leather, and bone charcoal; and to impurities in the quench. Under controlled conditions, the quench water will have such things as potassium nitrate dissolved and will be aerated by air injection into the quench tank."

Going back to another description found on the Internet, color comes from uneven temperature of the case in the quenchng solution. This is where air is pumped through the solution. Grey is when the quenching is even and complete. This can be either water, or in the carbonizing form of case hardening, oil is used, a carbon rich solution. So for case hardening, the difference is in how it was quenched. So technique does come into the picture.

Furthermore, in order to get the colors, all of this has to happen under controlled conditions. I think back then it was more art than science. If not properly controlled, perhaps grey case hardening results? This means perhaps this variable is what caused the difference in the results? Perhaps this is why bright case colors are rare and sought after?

Bob

 

[Captchee]

I think what he is describing is fire bluing/ charcoal bluing which is not to be confused with case hardening .
Did colt fire blue ?
From what I have read Winchester and Remington but they used a large sealed drum process
Also a good rust blue job will be clean and polished . Im not sure what colt used early on . However it would not surprise me if it was either fire blue or rust blue as both processes where in use and had been in use for a couple hundred year

 

[denster]

You went to all of that difficulty to restate what I had previously said. If you would like to see the case color process go to youtube and go to Midway USA channel. Larry Potterfield shows it being done in detail. The equipment is modern but the principal is the same.

 

[Driftwood Johnson]

Howdy

Here is a post with an excellent description of different kinds of bluing done over the years. Go to the 6th post and read the descriptions posted by James K.

http://thefiringline.com/forums/showthread.php?t=538119&highlight=carbonia

Case Hardening is an entirely different type of metal treatment. The purpose of Case Hardening is to infuse extra carbon into the surface of soft iron and steel. When the carbon content at the surface is raised, a thin layer, or Case, of hardened material is formed, while the interior of the part remains soft and ductile. Parts treated this way have superior wear characteristics, while the ductile interior prevents the parts from shattering under impact.

Parts are packed in carbon rich substances, such as ground bone or charcoal. Leather and animal hooves can also be used. The packed materials are placed in a well sealed box and heated to a high temperature and left at that temperature for a period of time. As the parts heat, carbon migrates from the carbon rich substances into the surface of the iron or steel, forming a thin layer of harder material. The amount of carbon and the depth of the hardening is determined by how long the parts soak at high temperature. The parts are then removed from the heat and quenched in water.

The colors of Case Hardening are a byproduct of the process, they have no intrinsic value or purpose. The metal takes on a mottled appearance of blue and purple, caused by the various compounds formed from impurities in the bone and charcoal. Although the infusion of carbon into the metal is permanent, the colors produced are relatively fragile. They often fade over time, and can also be erased by harsh chemicals. Long time exposure to sunlight can also cause the colors of Case Hardening to fade.

Even though the colors of Case Hardening have no purpose, the 19th Century firearm buying public came to highly prize the colors produced in the Case Hardening process. So many firearms companies developed their own secret recipes and process for Case Hardening, and jealously guarded their processes.



Colt Case Hardened the frames of their revolvers while they blued the cylinders, barrels, and grip frames.

This 2nd Generation Single Action Army was made in 1973. The colors of the Case Hardening are no longer as vibrant as they originally were, they have faded a bit over time.

This 2nd Gen Colt was made in 1968. Somebody removed the blue before I bought it, probably with something along the lines of Naval Jelly. The colors of the Case Hardening were also mostly removed, there is just a trace of them still visible.

This Bisley Colt was made in 1909. The blue has mostly worn off over time, and the colors of the Case Hardening on the frame have almost completely faded away. However despite the lack of colors, the hardened surface of the frame remains.

Throughout the Twentieth Century, Smith and Wesson always Case Hardened the hammers and triggers of their blued and nickel plated revolvers. Here is a photo from the late 1940s or early 1950s showing parts being quenched at the S&W factory.

S&W even went so far as to trademark their Case Hardening process in an attempt to keep cheap imitation revolvers from being imported. This 38 Military and Police revolver has REG.US.PAT.OFF. stamped on the rear of the hammer to protect their trademark. You can see the colors of the Case Hardening. Eventually S&W was not able to maintain their trademark on their Case Hardening process and they stopped marking their hammers this way.

 

[Captchee]

Maybe im miss reading here .
But let me say it again case hardening which produces the colors found on hammers , receivers , triggers , in ranges of yellow to brown and shades of blues and greys …. is not charcoal bluing
Todays hot tank blues are not always hot salt blue in the sense of Niter bluing which produces color by heat not by the salt itself .same with oil bluing . If you have ever seen a spring that’s been annealed in burning oil then you have seen oil blue . Again annealed not quenched .

 

[Captchee]

here is a link to 3 pages of discussion on bluing to include posts on Colt and thier period bluing process which it would apear was nothing new .
http://americanlongrifles.org/forum/index.php?topic=39695.0

sorry , jerry's barrel photo exspands the posts . so you will have to look on page 2 to see them .

 

[Driftwood Johnson]

Howdy Again

I thought I made it clear that bluing and Case Hardening are two separate processes.

The purpose of bluing is to protect the surface of steel from atmospheric oxygen and prevent corrosion. Most types of blues are actually a controlled type of oxidation, sealing off the body of the metal from oxygen to prevent rust.

Here is a photo of the bluing ovens in use at Smith and Wesson from the late 1940s or early 1950s.

Case Hardening is a very old process for hardening the surface of iron and low carbon steel. Modern metallurgy has pretty much made Case Hardening obsolete, modern steel alloys can be heat treated to harden them all the way through. But previous to that, the best way to prevent wear while retaining strength was to Case Harden the iron or steel. Infusing extra carbon into the surface of the steel creates a thin layer of harder metal. Again, the colors were incidental to the process.

Another name for Case Hardening is Carburizing, which simply means heating iron or steel in the presence of carbon to add more carbon to the surface of the metal. Next time you buy some blue or black hardened screws, you are buying carburized screws.

I know that if you place low grade steel into a type of crucible, fill it with wood charcoal and powdered bone, and then place an airtight top on, you can end up with bluish colors.

The OP is referring to Case Hardening here. This is not a blueing process.

One is a semi-matte black which can be shiny depending how the metal was polished. I also see a stark bluish-grey color on some barrels. Even though probably wood charcoal, bone, and other ingredients are probably involved with both results, there are evidentally two different techniques involved. BTW I find the barrels with the blue color to be very rare.

This is referring to bluing, although the OP is incorrect about the method used. Most of the older styles of bluing done during the 19th Century were not as robust as the bluing done to firearms today. The gray color on the barrels of old guns is simply the color of the old steel under the blue because the blue has worn off over time.

Here is the other side of my Bisley Colt from 1909. The blue on the barrel, cylinder, and extractor rod has simply worn off over time. Modern bluing is much more robust than the blue done at this time, it takes a lot more to wear modern blue off of a firearm. 100+ years of handling have worn the blue off of this old Colt.

 

[Jim Watson]

But isn't that little patch of blue on the trigger pretty?
Imagine all the small parts in "peacock blue" and the rest in furnace blue.

As DJ says, the case colors can fade, wear, or be removed - I remember a long SASSnet thread that blamed Ballistol - but the hard case remains.
You can have case hardening without the colors at all, just gray steel.

 

[maillemaker]

Driftwood has it right.

There are 3 things being discussed here, and none of them are the same.

Bluing
This is a controlled oxidation of steel or iron to inhibit rust.

Case Hardening
Pure iron will not take a heat treat - you can't make it hard by quenching it from high heat. You need to add carbon to do that. If you don't have carbon steel, or you still want a more malleable, ductile core while having a hard outer skin, you can case-harden an iron object. This is basically impregnating the outer millimeter or so of the object with carbon, making it carbon steel that will respond to heat treatment and get hard. Period case hardening started with a carburizing process that resulted in a mottled color appearance. This was purely accidental and not an intentional decorational finish.

Color Case Hardening
This is not case hardening at all. It is purely a cosmetic finish applied to simulate the effect obtained by period case hardening. Modern firearms are generally made out of modern homogeneous (all throughout) carbon steel that can be heat treated fully rather than needing an expensive secondary carburizing process. To make the finished parts look period case hardened, a cosmetic finish is applied to simulate the look.

Steve

 

[Hawg]

the case colors can fade, wear, or be removed - I remember a long SASSnet thread that blamed Ballistol - but the hard case remains.
You can have case hardening without the colors at all, just gray steel.

Or they can turn brown like my 1887 Winchester.

 

[denster]

Color case hardening is carburizing or real case hardening. It has the added value of providing an attractive finish. The utility of case hardening color or otherwise is still valid today where a hard surface surrounding a shock resisting softer core is necessary.
The finishes on some guns ie: Ruger SAs that simulate color case hardening are just that a simulated finish.

 

[Driftwood Johnson]

Color Case Hardening
This is not case hardening at all. It is purely a cosmetic finish applied to simulate the effect obtained by period case hardening. Modern firearms are generally made out of modern homogeneous (all throughout) carbon steel that can be heat treated fully rather than needing an expensive secondary carburizing process. To make the finished parts look period case hardened, a cosmetic finish is applied to simulate the look.

Well, you have to check out exactly what different manufacturers are calling it before you can make a blanket statement that Color Case Hardening is not real Case Hardening.

Here is a Ruger Vaquero made before they discontinued their Color Case finish. I am working from memory, but I think that is what Ruger used to call it. Yes, the steel is modern steel and it has been heat treated and hardened all the way through the metal. Yes, the colors were simply applied with some sort of chemical treatment. Ruger discontinued this type of finish when they got too many complaints about the finish rusting.

Here is a New Vaquero with the same finish.

Notice how blotchy the Ruger colors are.




Here is an Uberti/Cimarron Cattleman. Uberti creates this finish with a hot acid bath. And I believe it does impart a bit of hardness to the surface of the steel. For what it's worth, on their website Uberti calls this a Color-Case Hardened frame. Notice the hammer has colors too.

Here is the other side of that 2nd Gen Colt of mine. Notice how the colors have not faded so much near the barrel, they still maintain much of their original subtle color shift from blue to purple with a tiny bit of yellow. Probably because my grubby fingers did not get in that protected place so much.

Ballistol? Heck, Ballistol won't hurt the colors of Case Hardening.

 

[4V50 Gary]

Great posts guys.

I first saw color case hardening at the Ron Scott's Oregon Gun Makers' Fair. It's a great 2 1/2 day seminar that is well worth attending. We were taught color case hardening during our first semester Bench Metal class at Trinidad State. It costs $$$ though because you have to use a lot of energy to heat up that oven and sustain the heat.

 

[denster]

Nice pistols Driftwood and good explanation. The Uberti by the way is true color case hardening although not as deep as the hardening done by Colt. Uberti uses a molten cyanide bath to carburize and of course an aerated quench. An interesting video of it being done used to be on youtube.