Author Topic: Charcoal Blue  (Read 38558 times)

Offline Acer Saccharum

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Charcoal Blue
« on: August 26, 2008, 12:18:02 AM »
Here are some posts I saved on Charcoal bluing from the old ALR, from Jerry WH, LSU Tiger(Wayne McKay), Chris Immel and others.

Charcoal bluing (12L14)
by Wayne T McKay LSU Tiger
I've been asked to describe charcoal bluing, so here it is, no holds barred.
Prep for the barrel is really easy. First, have the lugs installed and sight dovetails cut, sights fitted, and vent drilled (liner, if used installed too). While I'm sure some try for a near mirror finish, that's not needed for this finish. Starting with a sharp, large mill file, draw file the barrel. Softer steels, like 12L14 will tend to clog the file and make "pins" which will make a deep scar in the surface. I make it a point to clean the file every two or three passes. After doing the top five flats, you can switch to a smooth cut file, but I usually stop here. The trick is to have a smooth, even finish on the barrel. If the rear sight is steel, polish it to match the barrel and install it in it's dovetail.
To handle the barrel from this point on, I attach a wire to the front barrel lug and run it to the recoil lug of the breech plug with about a foot of slack in it. Before starting the fire, degrease the barrel. I start with the bore, since I usually put a good coat of "RIG" grease in it after coning the muzzle to prevent rust. Here in Louisiana, that's a must! Denatured alcohol, from a hardware store, works great and after the bore is clean, degrease the exterior of the barrel. From this point until it's finished do not touch the barrel with bare hands! The oil in your skin will be enough to discolor the finish. That's reason #1 for the wire.
The charcoal that I use is for the "Big Green Egg" smoker. Brand isn't important, but the fact that it must be pure charcoal is. "Kingsford" and "Royal Oak" are great for cooking, but the briquets contain slag, binders, and other lovelies that could make your project a mess. Just make sure the bag is labeled "pure hardwood charcoal." You can dig a pit for charcoal bluing or use a box. My box is five feet long and six inches by six inches. The material is 1/4" steel. Fill the box (or pit... you could charcoal blue in a ditch) with charcoal and get a good fire going. You can use what ever means you choose to light the fire. I use plain lighter fluid. You should have glowing coals from one end to the other not here and there. A floor stand oscillating fan helps here.
When you have a good fire going, rake the coals to settle them and knock off the ash. Place the barrel in the coals (reason #2 for the wire) and cover it with hot coals, but add fresh charcoal to almost fill the box. Watch the fire to make sure you didn't smother it. Don't pack the coals, just let them settle naturally. The point is to keep oxygen away from the steel. Exposed steel will turn black! If every thing's going smooth, let the barrel cook for about three hours, adding fresh charcoal as needed. Some instructions call for removing the barrel every few minutes (!) to rub it down with powdered lime. I've never done that and don't see the point of pulling the barrel out of the fire to expose it to oxygen and plunge it back into the fire for a few minutes.
After three hours, remove the barrel with the wire (reason #3) and hang it to cool. except for dusting off the ash, leave it alone for three days to allow the scale to harden. Gently heat the barrel with a heat gun and apply paste wax (the type for wood floors) to seal the finish and buff. You're done!
As a final note, the color ranges from a deep, midnight blue to purple. Purple indicated that the temperature got a bit too hot in that spot. I have no idea as to how to control that! The pictures show my box with a 42" barrel to give you an idea of scale.
Wayne T. McKay

LSU Tiger:
Durability? Pretty good, but make sure the tang is inlet well to avoid bending it when you tighten the screw, or it will crack the bluing.

LSU Tiger
The only way you can pack the bore is to crush the charcoal into small pieces and pour it into the bore. The Schultz company makes charcoal for use in flower beds thats pretty small, but you can only get a 2 (?) pound bag. It's also moist, which may effect the outcome.
Wayne T. McKay

To fill the bore you just crush up charcoal, pour it down the bore and tamp it in. It does not prevent the bore from bluing but it does stop it from slagging . Slag is thick oxide that makes the bore rough. The charcoal I use is no larger than a pea in size. Smaller sized charcoal gives a more even color and reduces mottling or dark spots. Figure on a 20# sack per barrel, but the left over in the box can be reused if you smother it out.

Box Construction.
From Jerrywh
      You might also add that the best way to charcoal blue with the least charcoal is to put the barrel in a plain black  iron pipe packed with charcoal and with a cap on each end. Leave the caps loose pack the charcoal in small pea sized pieces. It is much esier and cheaper to get a piece of iron pipe than it is to have a box made with a lid. Also the temperature doesn't have to be over 800 deg. fer.  
   I put mine in an electric oven that I made myself but it doesn;t matter how you heat it as long as the heat is fairlly even. A large wood fire is as good as anything. I made a 48" long electric oven. the inside of the box is
6"x 6"

From LSU
I have three 3/8" holes spaced 18" apart in the sides of the box right off of the bottom to allow rain water to drain out. You could plug them with a bolt stuck into the hole, but I don't. I added them because that thing is heavy empty, but half full of water... GEEZ!
All I do to the bore is make certain it's oil and grease free. After a few shots (50 or so), the bluing is worn off of the bore. Wal-Mart would have the charcoal, but only during spring and summer. I get mine from a grill and patio specialty store year round. It costs a bit more, but I get a 40 pound sack.
Wayne T. McKay

What,if any, effect does the charcoal bluing have on engraving?
None whatever. My name is engraved on the barrel and looks fine.
Wayne T. McKay

Bluing and Precious metal inlay:
If you want to charcoal blue a barrel with gold inlay, what do you have to pay special attention to?
Suppose you get the barrel too hot? Will the gold melt?
Do you engrave the gold after it's been through bluing -or- before?

Chris Immel:
A LOT of European (particularly Spanish and French) barrels are charcoal blued with gold and silver "damascening" (metal inlay), and I've always wondered how it was done. I'll ASSUME that the charcoal pit isn't hot enough to affect the gold/silver....
In charcoal it is not the charcoal that blues the gun barrel, The only thing the charcoal does is keep excess oxygen away from the metal so as to stop it from slagging. If you want even color of blue it is important to have good clean charcoal.
Good clean pure wood charcoal will do real well. Impurities or dirt or oil of any kind will cause a mottled appearance or a change in the color. It is a whole lot better to spend $3.00 more for good charcoal than to do it over again. Fill the bore also.
It also will be more even colored if the charcoal is fine grained rather than big chunks. The heat should be fairly even from one end to the other. The idea of rubbing with lime was started by someone who confused the process of heat bluing of swords and gun barrels in Europe with charcoal blueing. Rubbing with lime may have been done before the barrel was put into the charcoal as a de greasing process but they were never taken out and re rubbed during the charcoal bluing process.
The heat bluing of swords and gun barrels was a totally different process.
The normal heat of charcoal bluing will not phase silver or gold inlays. Silver and gold inlays will stand up to 1500 deg fer. with no damage. [1525 deg fer. will not only melt them out but they will alloy with the barrel steel.] The longer they are held at 1525 or more the deeper they will alloy. Don't bother to look up the melting point of gold because it does not apply when it is alloyed with carbon.

« Last Edit: February 26, 2013, 10:35:02 PM by rich pierce »
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Offline Acer Saccharum

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Re: Charcoal Blue
« Reply #1 on: August 26, 2008, 12:20:14 AM »
Part 2

David Veith
Did a rifling lead this way. Dug a pit about 12" deep. Started a real charcoal fire. Then I put the lead in the fire bearing it in the charcoal. Once it got fair hot Then I cover the fire with dirt and left it there all day. The area that I did it in was mostly sand. The kids old sand box area. One will soon be 17. to give you a idea of what the ground was like.
David Veith

The little bit that I have done, others here have done much more, I have used the same charcoal I use for color case hardening purchased from brownells, I used the wood charcoal for this application. I also used a heat treatment furnace. I degreased the parts, placed them in the same crucible I use for case hardening, sealed them up, and placed them in the furnace at 900 degrees for one hour. After this I let the parts cool down to about 100 degrees, pulled them out and degreased them again (not sure if this step was necessary) and than placed them back into the crucible and brought the temp up again to 900 degrees. Following that I let them cool down and than coated them with some oil (cutting oil if I remember right) and than let them sit overnight. I think that perhaps re-positioning them in the pack was probably the key to success, the second degreasing probably wasn't necessary. In any event, I got a nice even wet ink black blue which was what I was looking for. Most of what I did was just from reading Jerry's posts. My furnace is big enough for a pistol barrel, but a rifle barrel would be an entirely different situation. The one problem that I have is that the color of the blue was not all that different from a good hot blue, most people would never recognize it for what it is.

44 henry's blue was too dark because he went up to 900 deg. For the nice charcoal blue you should stay under 800 preferable 750. I have done bluing at 900 that came out like a black mirror.
For a real nice charcoal blue put the barrel inside of a black pipe packed in fine charcoal. Do not use briquettes. For a nice even blue crush the charcoal up very fine. Don't let the barrel touch the sides of the pipe. A good way to do this is to take a pipe of the required length. Get two pipe caps and drill a 7/16 hole in the middle of each cap. Put one cap on the pipe and slide a 3/8" rod thru the pipe cap until it extends out the other end of the pipe. Put a couple of handfuls of charcoal into the pipe and then slide the barrel onto this rod and into the pipe continue to fill up the pipe with charcoal until it is full and then place on the other cap. The caps need not be tight. DO NOT make the pipe air tight. Air will not enter the pipe with the charcoal in it. If it is air tight it may cause an spontaneous and instantaneous disassembly. For you Democrats that means [BLOW UP]. You can place this pipe in a wood fire if you wish or heat with an oven. They did have ovens in 1700's. even in America. It will not be necessary to repack this barrel if you wish to do something that you think will even out the color. Take the pipe out of the fire and just roll it around some. the charcoal will loosen up some after it is in the fire a while. NO CHARGE.

I was in Williamsburg several years ago and I stopped in at the gunshop and it just so happened the George Suiter and Richard Frazier were charcoal blueing two gun barrels at the same time. I hung around the shop for the better part of the day watching and asking questions. Man, I can be a pest, those two have the patience of saints!!!!! The next day I stopped in again and George had one of the barrels and its breechplug in the shop and he showed me the finished results. A nice even color that I have never seen duplicated with chemicals. He said the barrels needed to sit for a couple of days for the color to harden and then the barrels would be warmed and coated with oil. I made a metal box about 60 inches long by 6 inched wide and tall out of a steel shower stall liner I salvaged out of an old house I was remodeling. It was a little flimsey when I set it up and burned all the rest of the paint off the metal, so I riveted two pieces of small angle iron to the long sides to stiffen it up. I've used it only one time, pretty much the same as in the article in JHAT by Dave Wagner. My results were less than satisfactory but hey, thats part of the learning process. I did use the cowboy charcoal for the bulk filler and some of the Brownell charcoal packed around the barrel. I did not remove the barrel and wipe it but just left it sit in the trough for a little over an hour.

If you want to leave the breach plug in the barrel you can just stick a 3/8 stud in one end. That will hold the barrel in the middle at that end. you can then slip a big washer over the tang on the other end to hold the barrel in the center. All you need is a piece of sheet metal with a hole in it to go over the tang. I really prefer to case harden all my breach plugs . It gives them some more color spectrum. Case colored breach plugs go dood with charcoal bluing. To each his own.
The blue won't hurt the bore any at all if the barrel is packed good with fine charcoal. It is a good idea to oil the bore as soon as the barrel cools of enough. Let it cool in the pipe. You won't need to worry about the barrel getting too hot if you don't use any draft in the fire. This process is very close to case hardening except the part is not quenched and it is not brought to such a high heat. I have held parts in chacoal at 1500 deg fer. for 4 hours and when they were unpacked there was no scale.
The most dangerous thing about charcoal bluing is warping the barrel. That is why it must be well packed well in fine charcoal. Besides evacuating almost all the oxygen the charcoal give the barrel even support.
Ron Scott and I use an electric furnace but I wouldn't hesitate to use a wood fire as long as there was no draft to run the temp up.
I would build a very big fire and let it burn down to the coals. Then I would bury the pipe in the coals and just leave it in there.
After the coals burned down I would remove it. After the pipe cooled enough I would inspect the barrel. If it looked pretty good I would oil it in side and out.
I'm not sure why 44 henry's barrel came out darker . whithout seeing it I can only guess. As long as the barrel is in charcoal over heating it shouldn't hurt aything but the color maybe.
Make sure not to use a galvanized pipe. USE BLACK IRON PIPE.

Here are some facts I learned about different kinds of bluing while experimenting. If you give something a high polish , don't pack it in charcoal and put it in the oven at 800 deg fer. for 20 to minutes it will come out like a black mirror. If it is left in there very much longer it will still look the same but the black will chip off when hit just as a porcelain finish will.
If you pack the part in charcoal it will come out charcoal blue at the same temp.
When you oil the charcoal blue it will get very dark . Then after a few days it will lighten up again and look normal. When I first oiled one of the barrels I thought I ruined the color. Here is another thing I tried. In trying to get a even color I wiped the barrel with a real fine coat of oil before I put it in the oven. It seemed to make it more even but as far as the color was concerned it never made any difference. I wiped one with lime real well before I put it in the oven and it did not want to color very good at all.
« Last Edit: August 26, 2008, 12:21:57 AM by Acer Saccharum »
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