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Color case hardening

Posted: Mon Dec 11, 2006 6:20 pm
by Jim D
Does anyone out there know the specifics as to how Marlin color cased
the 1893's? Bone to wood charcoal ratio, additives such as Potasium Cyanide or charred Leather in the pack? Quench water temp, additives such as Potasium Nitrate, aeration etc? I've looked in Brophy's book but couldn't find anything on CCH. In talking with Oscar Gaddy a few years ago, he mentioned a film clip from the 30's showing a number of receivers bolted together in a rectangular crucible, and the lid and contents being dumped in a quench tank, but that's all I've ever heard or read on the subject. A 3:1 wood to bone charcoal ratio gets close, but I don't get the blue turquiose swirls and patches.

Any information is greatly appreciated!!

Jim D

Posted: Mon Dec 11, 2006 7:20 pm
by Regnier (gunrunner)
Jim D.;

The film you mention does exist, but there is no information about the temperatures or time in the ovens mentioned. The parts are packed into the iron box (not bolted together) with the bone and charcoal mix then the box is sealed with a clay type substance to keep the gases inside the box. After the box has been the oven the time required, it is dumped into a barrel of water to quench all the parts and wash them. There is a pipe going into the barrel at the bottom flowing water into the barrel at all times. So I suspect it is room temperature water going into the barrel as the water overflows the top of the barrel at all times.
An attorney in Washington D.C. studied the film and learned how to case-color Marlins. He got VERY good at it. Unfortunately he died several years ago and the secret is gone. He did write an article that was published in the Marlin Firearms Collectors Association, Ltd. newsletter explaining the process, but non of the secrets as to time, temperature and mixture. Sorry......
I hope this helps.

Posted: Tue Dec 12, 2006 11:47 am
by Jim D

Thanks for your reply! I have not seen the film, and this is the first that I've heard about the pipe and the constantly flowing water. From my experience, the temperature of the quench water does determine the
quality and brightness of the colors that you get. Much above 50-60 deg F
and the colors start getting "blah". Aeration or disolved Oxygen has an
affect as well. The constantly flowing water is probably sufficiently aerated,
cool enough to get good colors, and most likely not contain any additives such as Potasium Nitrate. I wonder what they did with all of the carburizing material after each quench? Maybe they emptied the tank once a day. The constantly overflowing water would keep the Tri Calcium Phosphate levels from the bone charcoal in the tank from constantly increasing. Bolting the receivers together would tend to concentrate the colors as well. I wonder if you can tell from the film if the outside receiver faces have a plate bolted to them? Anyway, your post has definately shed some light!

Posted: Wed Dec 13, 2006 6:03 pm
by Regnier (gunrunner)
Jim D.;

It has been a while since I viewed the film, but I do not remember seeing anything attached to the receivers before being packed into the iron box. As I rememeber, they simply placed the receiver in the box and packed the charcoal and bone mix in and around the parts. Then the box was sealed and placed into the oven. When the box is removed, it is simply dumped into the barrel with quite an explosive shot of steam. I think the mix is washed out of the barrel with the overflowing water. The parts are caught in a metal basket inside the barrel.
I will try to get another look at the film......

Posted: Thu Dec 14, 2006 1:04 am
by Jim D

The mix <should> sink. There might be a few pieces of the wood charcoal that float, but every mix I've ever used, sinks. It should drop right through the basket to the bottom of the barrel. The constantly flowing water would help keep Tri Calcium Phosphate levels from rising from quench to quench. That would be important to insure consistant colors from batch to batch. Otherwise I would think they would have to start over with a clean barrel and fresh water each time.

One other thing that can affect the results is how far the parts drop through the air before hitting the water. Can you tell from the film?

Thanks for your help and interest!


Posted: Thu Dec 14, 2006 12:41 pm
by Regnier (gunrunner)
Jim D.

As I remember, the parts drop less than a foot to the water. As I said, I will try to review the film, maybe this weekend.
The mix I see in the film appears to be finely ground up and no chunks of charcoal. If I get a chance to review the film, I will pay more attention to all aspects of it.

Posted: Thu Dec 14, 2006 1:27 pm
by Jim D
Some things to watch for that could provide clues:

1. If there are multiple receivers, are they bolted together?
2. If they are, is there an end plate on the outside of the outside receivers?
3. Does the lid get dumped into the tank with the receivers?
4. How far do the contents drop through the air before hitting the water?
5. Are there visible air bubbles in the water, besides just flowing water?
6. I'm guessing the film is B&W, but can you tell if the crucible is glowing,
and if so, how brightly? That would give a clue to the temp of the contents at quench.
7. Can you tell the orientation of the receivers as they enter the quench, ie: top, bottom, front, back side goes in first.
8. Are there other parts in the pack like levers, hammers, butt plates, or were these done separately?
9. How tall is the tank?

Thanks again!!

Posted: Thu Dec 14, 2006 1:41 pm
by Jim D

I think what I'd like to do is to build a setup like what Marlin uses in "the film", build a crucible like the one in "the film", and just see how close it
comes to duplicating original Marlin colors. I'll document the process and results with photos and post them on this forum. It's been a long, long time since I last asked anyone if they've watched "the film". :shock:

Posted: Thu Dec 14, 2006 8:59 pm
by marlinman93
You might want to give a call to the folks at Ballard Rifle in Cody, Wy. They don't do repeaters, but their colors on Ballards are spot on for Marlins. I had them do a Ballard action for me, and the colors look very much like the colors seen on early Marlin repeaters, and Ballards.

Posted: Fri Dec 15, 2006 12:34 pm
by Jim D

I'm in Cody quite a bit, and I've wanted to, but just never have gotten around to stopping in. I've watched their video clip on CCH at the Buffalo
Bill museum and it looks like they are getting some beautiful colors. They
mention that their pack mix includes "secret ingredients" which might be
Potasium Cyanide. Potasium Cyanide from what I've read produces more
vivid colors- I've never messed with it. An old book, "The Modern Gunsmith" (I believe) gives a formula that includes, along with wood, bone and leather charcoal, Potasium Cyanide and has a statement that if the colors are "too gaudy" to omit the Potasium Cyanide. I've tried leather charcoal before and noticed no difference. It's a pain in the rear to make your own, and nobody sells it that I've been able to find.

My desire to duplicate the methods that Marlin used in "the film" is
based on the desire, through the process of elimination, to determine if Marlin might have used Potasium Cyanide or other additives. If I can duplicate the crucible, tank setup, etc, etc, and I do NOT get "Marlin colors",
then it pretty much has to be the mixture of the pack.

Anyway, I hereby vow to stop in to see the folks at the Ballard Rifle Co the very next time I'm in Cody!!!

Thanks for your response!

Posted: Sat Dec 16, 2006 4:27 pm
by Regnier (gunrunner)
Jim D.;

Just finished reviewing the film. From what they show in the film, they pack several receivers (only) into the box. The receivers show no blocking plates and are individually packed. The box (which is on short legs) is filled with the "mix" and taken off screen to the ovens. The top is not shown placed on the box, but you can see lids on the floor next to the ovens. The states "after 3 or 4 hours" in the oven, the box (which appears to be quite hot) is removed. It is taken to the water barrel and dumped into the barrel. The bottom of the box actually touches the water just prior to dumping. It is dumped quite quickly once it is over the water barrel. You can see the water flowing over the top of the barrel, and it would appear that there is air bubbling too. After the parts are taken from the basket in the barrel, the parts are rinsed in the quench water barrel to remove any residue of the "mix". That is all that is shown.
The article I mentioned goes into quite a bit of detail about color-case hardening. It mentions that the oven must be above 1200 degreesbefore any casehardening can begin. He mentions that the box is red hot when it is removed from the oven. He also mentions that after the parts are rinsed, they probably are reheated to about 250 to remove all the remaining quench water.
If you want, send me an email with your address, and I can photocopy the article and send it to you.

Posted: Sun Dec 17, 2006 1:11 pm
by Jim D

I sent you an email with my address. I appreciate all of your help and
everything that you do to benefit this forum!


Posted: Wed Dec 27, 2006 7:17 pm
by Jim D

I received the copy of the article today, thanks! Unfortunately page 8 was missing which covered what happened between pulling the box from the furnace to quenching.

A couple of interesting things that I noticed from the article:

According to the article, the lids were removed when the box was taken out of the furnace, then carried over to the quench tank. That would expose the mix and possibly parts to the open air for a fairly long period of time. That appears to be in contradiction to what Oscar Gaddy told me a number of years ago where he mentioned that the lid, mix and contents were all dumped into the quench tank. Oscar's theory was that the lid pushed the water out of the way as the parts entered the barrel, then collapsed back around them. In my experience, I've found this to be a very important factor.

I was also surprised to learn that the quench barrel was only knee high. The colors are formed as the parts cool through the temper color range, below 700F, and with such a short drop, they may be reaching this temperature AFTER they are resting at the bottom of the basket. The position the parts are in when they cool below 700F makes a difference in the colors and uniformity of coverage. For example, the side that's down may get colors whereas the side that's up, won't. I drop my parts through a fine mesh sleeve that keeps the parts upright while cooling.

One last thing I thought was interesting was regarding the mix. There was a screen shot from the film that said "One method is to pack them in powdered charcoal and bone, and place them in a hot oven." I'm not sure how to interpret that. What type of charcoal are they using, wood?, leather?, peach pits? Is the bone, bone charcoal, or bone meal? Also, the
way this is written is maybe a little evassive. "One method is..." instead of "This is the way we do it..." Mr. Baker mentions charred leather when he talks about casehardening materials. Maybe this was part of his mix.

Anyway, the article was very interesting and I appreciate your sending me a copy. It certainly gives me a lot of factors to consider!



Posted: Thu Dec 28, 2006 12:19 pm
by Regnier (gunrunner)

Page 8 is on the way....sorry about that.
I thought I had checked to make sure all pages were present, but apparently not.

Posted: Thu Dec 28, 2006 12:30 pm
by Four-Eyed Buck
Jim D, one thought on the mix. The ingredients might be a propietory thing. IE: each company has it's own "Mix" to attain "their" colors.......Buck 8) :wink: