Charcoal blue

[J.D.]

Rather than highjack the "barrel treatment" thread, I thought it might be more informative to begin a new thread on charcoal bluing.

I have looked in several of the gunbuilding books in my library, and did find  basic instructions in "The Gunsmith of Grenville County"  as reported by George Suiter.  (Page 314, 315) Alexander reports that the bore won't be damaged if the temp is kept at about 700 degrees F.

I have found that many articles, and a lot of misinformation have been written by people who have only read about a certain topic, rather than passing on information written from actual, first hand experience. So, I'm curious if anyone has actually tried charcoal bluing at 700 degrees, plugging the bore, or filling the bore with charcoal powder to prevent scaling. If so, how well does it work? How is accuracy affected?

Personally, I can't afford to ruin a $200 barrel on someone's word, based on written material than may, or may not be accurate, so what I am looking for is information from someone who has charcoal blued a barrel, as opposed to reports of written material.

In talking to Gary Brumfield at the CLA show,  he reported that he had to freshen a charcoal blued barrel, to remove the bore scale, to restore accuracy in a barrel he charcoal blued.  He went on to mention that 18th century news papers advertised bluing, boring and rifling, in that order. Also reported on page 314 of GOGC. He suggests that barrels were charcoal blued prior to boring and rifling to avoid the scaling in the bore.

Personally, I dunno. Logically, if a scale is formed on the exterior of a barrel when it is subjected to heat in a carbon rich environment,  it follows that same scale will also form in the bore in the same carbon rich environment.

So, has anyone actually charcoal blued a barrel and shot it for accuracy afterward?

I hope everyone understands that I do not intend to disparage anyone or to initiate a controversy. I am merely trying to get to the objective truth concerning any detrimental effects that charcoal bluing might have on the bore of a charcoal blued  barrel.
Thanks,
J.D.

[Jim Thomas]

I've blued two barrels.    I've packed the bore solid with charcoal dust before baking and haven't experienced a scale....or accuracy problem.

Here's the thing.  I've seen charcoal blued barrels that look as though they were rolled in pancake flour.    Mine come out shiny.  Some blotching with a red hue here and there.  I'm not sure if my results are what is to be expected/proper.  A gunbuilder at Dixon's told me charcoal blue should look shiny.   My bluing will chip off if bumped hard.    You can't bend the tang etc after the bluing process for example.

     

 



 

[flintriflesmith]

The barrel that I freshed after bluing was not because of a lack of accuracy--it just seemed hard to load. I don't think the smooth scale in the bore hurt accuracy at all but the buildup of even a couple of thousandths can change how the rifle loads. I don't think the microscopic surface of the bluing is as smooth as polished steel.

That said, I did not shoot the rifle or measure the bore before bluing so it may be that it had a tighter bore than normal to begin with. It would not shoot the same patch and ball combo that I had used in other .60 cal rifles.

Another concern is what the conservation folks call "preferential pitting." If the scale is left in the bore and a patch of it does flake off that spot would be exposed to the corrosive elements in the bore and could become a point of attack. You may have witnessed this on the brass mounts of a gun that someone lacquered years ago. If the coating chips corrosion begins there and progresses more rapidly than it would on a piece of untreated brass. That is why most collectors have switched from hard lacquers to "smear coatings like wax.

[Acer Saccharum]

I posted some of my gleanings from the old ALR int the tutorial section on Charcoal Blue:

http://americanlongrifles.org/forum/index.php?topic=918.new#new

[Kentucky Jeff]

I know Mark Silver has done some charcoal bluing.  He had a rifle at the CLA show last year that was charcoal blued. 

[44-henry]

I've never done it to a barrel but I've charcoal blued some smaller pieces just to see what happens. I used a heat treatment furnace and wood charcoal from brownells. I do admit that my temp was higher, about 900 degrees and the color I received was very black, almost wet ink black.

[J.D.]

I appreciate everyones replies.

I apologize to Gary Brumfield for misinterpreting his comments about freshening a bore due to scale. I apparently misunderstood the reason for freshening that barrel.

Acer,
Thanks for posting the information in the tutorial. I had forgotten about the tutorials, assuming they haven't been transfered from the old board.

So, if one packs the bore with CLEAN, small charcoal, and heats the well polished barrel to 700 degrees, or less, the finish will be a shiny blue, and the bore should not scale.

A friend has an old pistol barrel that has been laying around his shop for years. Maybe I can persuade him to participate in an experiment with charcoal bluing. I wonder how good and trusting of a friend he really is?   

Thanks,
J.D.

[Acer Saccharum]

Just for experimenting, you can charcoal blue a piece of polished barstock or water pipe.

Tom

[Jim Thomas]

I appreciate everyones replies.

So, if one packs the bore with CLEAN, small charcoal, and heats the well polished barrel to 700 degrees, or less, the finish will be a shiny blue, and the bore should not scale.

Thanks,
J.D.

If I do a 3rd barrel, I will stick with charcoal dust packed tightly in the bore.  The bore will coat with a microscopic scale as flintriflesmith stated and I agree with everything else he said.      I've never experienced any rough scale.   That is what I meant when I said I've never had any scale problems.             

From my limited experience,  enough can't be said about packing  the barrel with fine...pea sized charcoal.   On my first attempt, I used charcoal broken down to about the size of a golf ball.   I got more blotch than I did when using pea sized on the second job.       

[jerrywh]

 Why is there no scale when a piece of steel is pack case hardened?  Same thing.

[Acer Saccharum]

What is the difference between FIRE BLUE  and CHARCOAL BLUE?

Fire blue is just a heat blue, and is not very durable.  Is charcoal blue more durable?

[T*O*F]

What is the difference between FIRE BLUE  and CHARCOAL BLUE?

The "soak time."  The longer the soak, the thicker the oxide coating.

[jerrywh]

The "soak time."  The longer the soak, the thicker the oxide coating.

  Only if the metal is exposed to oxygen. If packed in charcoal properly it is not.

[Acer Saccharum]

This appears to me to be a watery thin blue, one which may not be very wear resistant. If I had to guess, I'd say it was a heat blue. (Even tho' the gun is 200 + years). Can this kind of blue be achieved in a charcoal pack?

Hauschka fowler:


Hauschka fowler, farther up the barrel, looks very dark and highly polished:


Fancy Jaeger:


Guns in the collection of the Metropolitan Museum, NYC

[jerrywh]

 I can't tell from the photos but my guess is that it is a heat blue. To begin with the heat blueing on guns was done by the sword bluer's. Sword bluer's were the first to do it and as far as I have been able to discern they were gilded like all the other trades. Some of the English gun books by Neal and Back stated that one of the trades was the bluer's. The sword bluer did it in a huge pile of hot sand. The barrel or sword was inserted into the hot sand and withdrawn from time to time to determine the color. when it was correct they turned the barrel around and did the other end. The sand was piled on top of a huge iron plate that sat on top of a forge.  Somewhere back in time I have seen a engraving of this being done.

[flintriflesmith]

What is the difference between FIRE BLUE  and CHARCOAL BLUE?

The "soak time."  The longer the soak, the thicker the oxide coating.

Fire blue is the same as draw blue or spring temper blue. The temperature is a good bit lower than that used in charcoal bluing. Both are oxides.

Whenever I have found traces of charcoal blue on the bottom of longrifle barrels it was thicker than fire blue -- to the point of being a opaque scale. It is also much more grey than fire blue. I have never seen the slick, black version of charcoal bluing, that some modern builders like, on an American rifle but I have examined one 1820ish Jaeger that appeared to have that finish on both barrel and mounts. Those mounts were highly burnished before bluing but the barrel was left with s super fine drawfiled finish.

Gary

[Jim Filipski]

Acer,
Somewhere I recall reading about jaeger barrels being heat blued by the insertion of a red hot iron rod in the bore.
Can't remember where but possibly on our old Forum(?)
Jim

[Acer Saccharum]

Jim, I remember reading something like that. I have a hard time imagining that it would be an even heating. I also think it could scuff the bore up pretty good.

I contacted my steel treater, one I use for my industrial heat treating, and they said they could easily heat blue my barrel. They have a furnace with nine zones in it, and can guarantee +/- five degrees. I will try the fire ans and method first, andif it doesn't work to my satisfaction, I can polish the barrel up and take it to them.

Tom

[flintriflesmith]

Acer,
Somewhere I recall reading about jaeger barrels being heat blued by the insertion of a red hot iron rod in the bore.
Can't remember where but possibly on our old Forum(?)
Jim

Jim and Acer,
I believe the use of a heated rod to add a "blue tinge" (if I remember the wording correctly) to the barrel is from the German translation in Volume III of Journal of Historical Armsmaking Technology. I'm not sure if it referred to all barrels or just Jaeger barrels. Some one can probably dig it up.

Gary

[Chuck Burrows]

Is this the one?

The process is well described in the P.N. Sprengel's 1771 HANDWERKE UND-KUNSTE IN TABELLEN:

"For further beautification, the barrel is treated to allow it to oxidize to a blue color,...The gunmaker can rub the barrel down with a sweet-oil cloth so the ash which he dusts through a linen cloth adheres to the barrel; he then lays the barrel onto glowing coals until it begins to turn blue.
The best way to blue the barrel is, after polishing, to insert a glowing mandrel, which the tradesman calls a piston into the bore, and to rub the barrel with bloodstone as soon as it -begins to turn blue due to the heat of the piston."

[flintriflesmith]

Is this the one?

The process is well described in the P.N. Sprengel's 1771 HANDWERKE UND-KUNSTE IN TABELLEN:

"For further beautification, the barrel is treated to allow it to oxidize to a blue color,...The gunmaker can rub the barrel down with a sweet-oil cloth so the ash which he dusts through a linen cloth adheres to the barrel; he then lays the barrel onto glowing coals until it begins to turn blue.
The best way to blue the barrel is, after polishing, to insert a glowing mandrel, which the tradesman calls a piston into the bore, and to rub the barrel with bloodstone as soon as it -begins to turn blue due to the heat of the piston."

That's what I was remembering.

Gary

[Jim Filipski]

Ok ......Who is going to try it first? I'm finishing another jaeger this month. If I were getting good money for it I would attempt it as an experiment ( $#*! it ain't mine! )
May be someone could try it on a barrel scrap and report back  Good luck with the Bloodstone(?)
Jim

[Jim Filipski]

I have a question concerning scale. How come if I temper, polished tool steel or temper blue polished screw heads for that matter I do not get scale on the surface? Wouldn't that be the same for a barrel that has been heated to temper blue with a heated "piston"?
(Not talking about the soaking heat of charcoal bluing)

[Dphariss]

I have a question concerning scale. How come if I temper, polished tool steel or temper blue polished screw heads for that matter I do not get scale on the surface? Wouldn't that be the same for a barrel that has been heated to temper blue with a heated "piston"?

There were sometimes subsequent treatments to the steel. I would have to look up the meaning of the things they write of being used to rub or coat the barrel as part of the process.
Winchester used to use saltpeter with some manganese dioxide added to blue barrels by submerging the part in the molten saltpeter. Apparently this was Winchesters bluing technique in the 19th century.
To deepen the color they then coated the part with oil and "baked" it.
This is *may* not applicable to the 18th century but then again it might be.
The problem with any oxide is getting the same in the bore.
In making BPCR match rifles I rust blued because it left the bore white and produced less metal and powder fouling in the bore in use. Modern bluing methods using caustic salts puts a rough (relatively) coat of rust in the bore that often takes a lot of shooting or handwork, light lapping, to remove. Thus when I see people talking of scale and other such things on the outside I wonder what is going on in the bore and its something that makers should think about.
If packing the bore bore with charcoal prevents this all is well and good. If not I am not interested.

Dan

[D. Taylor Sapergia]

I had Brian Dancey make me up a steel trough 54" x 6" x 6" and acquired a bag of charcoal from Sydney with the intension of charcoal bluing longrifle barrels, but have not done so for fear of ruining the bore with scale.

I want to hear from someone who has achieved the blue finish we're looking for, and can comment on the bore's condition.  If it is not polished as before the process, I am not interested either.