Color case hardening

Anything to do with gun smithing.
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Regnier (gunrunner)
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Post by Regnier (gunrunner) »

Jim D;

In the articles I sent you by Joe Baker, he mentions leather in the mix. Do you suppose that the tannic acid in the leather from tannning the hides has something to do with helping with the "rainbow" colors? I believe that leather was mentioned in the internet articles I sent to you too.
I do not remember if leather was mentioned in the film. This might be something to consider if you are looking for more of the reds, yellows and orange colors.
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Post by Jim D »

Hi Rick,

The film mentions only wood and bone charcoal in the mix, but that doesn't mean that they didn't use it or at least try it at some point. As you can see from the different photos that were supplied to me, there is a vast difference in the colors and patterns from 1900 to the 1920's. Something caused those differences, and it is quite probably the ingredients of the mix. Leather charcoal is impossible to find. I've talked with the folks at Ebonex, who make the bone charcoal, about making a small run of leather charcoal. No way. I did try to make my own at one time- never again! I probably didn't get it charred enough but I didn't get
good results with it. It takes a huge amount of leather scraps to make a little charcoal. The by-product is huge clouds of choking black smoke.

I know that some of the old formulas call for leather charcoal as one of the ingredients, so there must have been some reason that it was in there.
I just don't know enough about it, or know of anyone using it to get some feedback from. The tannic acid could be a factor, I don't know.

If anyone out there in Marlin land knows of anyone using leather charcoal,
or a source of leather charcoal, I'd sure like to know about it!! If I could find some, I'd love to give it a try and post the results.

-jim
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marlinman93
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Post by marlinman93 »

It appears the colors on the left side of both actions are spot on, but the right side was less fortunate, especially on the small action.
I agree with Sure Shot, in the idea of a CD to watch the process! I'd pay money to watch you go through the various steps on a DVD or CD! What brand and type of furnace do you use? I assume it's electric? I guess a good kiln for pottery would suffice in doing this type of work?
Vall
Marlin lever actions 1870's-WWI, Ballards, and single shot rifles!
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Post by Jim D »

Vall,

Yes, I use an electric furnace. Marlin I'm sure used a gas furnace. The significance MIGHT be that a gas furnace depleted more of the Oxygen in the atmosphere than an electric furnace would have. However Oxygen plus Carbon MonOxide which creates Carbon DiOxide is still the primary chemical reaction that carburizes the material. So, the reduced Oxygen levels in a gas furnace might not be a factor. The crucible is pretty much sealed so what happens inside the crucible probably acts as an isolated environment.

The important thing to note from these tests is that each piece is carburized in exactly the same environment. There is no question to that fact. They are dumped into the quench in exactly the same direction since they are bolted together. So, what is the difference? The difference is ONLY their position in the crucible, and how the quench water washes over the pieces. That's it. Everything up to the point of the quench is absolutely the same.

Now, if I can create "Marlin colors" on one side, but not the other, why is that??

First, we need to define what "Marlin colors" are on the front side of the receiver. On this post, the only example of front side Marlin colors are from Don's 1893. There is a substantial difference fom the front side to the back side of Don's rifle. I didn't post front side pictures on my 1893s,
but I can tell you that the colors and patterns are substantially different from the back side. So, what would cause that? If you look at the two different faces, look with an eye of how water flows around the peice when it is quenced. One side is flat, with no openings. The other has a large hole in the middle, and a large massive bolt if it is quenched with the bolt in place. Maybe it doesn't sound like much of a difference, but enough to alter the flow of quench water from one side to the other.

That is all it takes. One side Marlin colors, the other not. Same mix,
same carburizing, same direction into the quench. Everything else is the same. Period. The effect of SHIELDING, and SURFACE CONTOURS are the ONLY variables.

I would love to do a study of Marlin Case Hardening from the 1880's through the 1930's, with photos of all four sides of high condition guns.
I'll bet nothing of the sort has ever been done. Whether for Marlins, Winchesters or whatever. Wouldn't that answer a lot of questions!!!
Rick, Vall, Don, do you guys know what all four sides of a Marlin looks like, or should look like for any particular period? We've seen that there is a tremendous variation. This forum presents a great opportunity to solicit photos from members and catalog the differences and evolution of Marlin case hardening. Wouldn't it be great to post photos, in cronological order, just to try and analyse what was done, and maybe identify changes in the process? Questions have been raised about how to identify original vs redone CCH'ing. Maybe this is the answer.....

-jim
Last edited by Jim D on Fri Mar 09, 2007 9:29 am, edited 1 time in total.
oodmoff
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Post by oodmoff »

Jim, What have you noticed in the past from extending the shielding slightly across the face of the reciever. I'm sure you spent extensive hours coming up with what works best already, I guess I was just curious as to your results in the past. Also I was curious as to how the finished tops of the last recievers you did came out (maybe a photo). I have always noticed that this "area" often provides the largest range of colors on the original marlin frames and this was the primary area you used for shielding.
Thanks
Darin
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Post by MDH »

New guy here

First let me extend a big thanks to Jim D. for all his help. I had been planning on getting into CCH for some years now; but it’s been a round to it project. By posting his information and hard work, and some e-mails; jump started my own CCH research.

I’ve done about 25 quenches so far, each quench consists of 4 pieces of 2x4 x 1/8 inch 1018 steel that’s been surface ground flat ( +/- .0005, to check for warpage).

I do 4 quenches using the same setup ie.. Same wood/bone ratio, water temp, quench temp etc (I do this 4 times to try and rule out any anomalies). What I end up with is 16 pieces of steel that have been CCH’d using the exact same process. Then I will change one variable and do it all over again.

Here is what I have found so far in my very limited testing (your results and mileage may vary)


Wood to bone ratio 3:1 vs. 2:1 – Little to no impact
Distilled vs. Well water- Little to no impact
Dirty vs. Clean water – Significant impact esp. after 3 quenches with same water.
Water temp: Significant impact, colder is better.
Quench temp: Impact, I get more reds at higher quench temps.
I’ve done one quench using charred leather instead of bone, Very faded & washed out
colors.

Some other notes:

-Got colors in all quenches
- No shielding used
- All quenches were done using air during quench
- Areas that cooled quicker (outside edges, areas around holes) got more browns. Center areas got more blues & reds.
-You can re-case pieces without having to anneal (this is for test pieces only, would not try doing it on any “real” parts). I have not tested depth of case after doing this.
- Sometimes if article is too close to side of crucible colors are not as pronounced or may have grey spots.

After another 50 or so quenches I should have a clearer picture of what variables have significant impacts.

Jim: thanks again for sharing.
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Post by Jim D »

Darin,

Excellent question! The colors do tend to be more concentrated on the top of the receiver since that area is blocked from the quench water hitting it directly. In this area the mix stays in contact with the steel for a longer period of time since it is not immediately washed away. Areas that are more exposed tend to have fewer colors. That's why the colors tend to wash away towards the bottom of the receiver. With the receivers going into the quench top first, since that shielding is on the top of the receiver, the areas towards the top get the most colors and patterns. You can really see that on Don's 1893 and some of the pieces that I've CCH'ed.

The way to envision what's happening is to picture the shield entering the water. As it goes in it pushes the water to the side, and then the water starts to colapse back on the sides of the part. As it colapses, it washes over the mix that is falling through the quench with the receiver, and hits the receiver in a perpendicular direction, holding the mix against the steel for a fraction of a second longer. Further down the side of the receiver, the water starts hitting the sides at an angle, washing the mix away from the steel instead of holding it there. This is where the colors start to drop off.

I've got almost too much color on the top of the ones that I've done, and they are a little dark. If I move the shield up some from the top of the receiver, I will get lighter colors on the top. The fact that original Marlins had a lot of color on top leads me to two conclusions: 1. The receivers went in top first like the film shows. 2. I believe they dumped the lid in the quench with the parts. There had to be something that shielded the tops of the receivers otherwise you wouldn't see the colors that you do on the tops of these guns.

If I put a piece solid shielding on the sides of the receiver I would get a solid area of color, probably with no pattern since the mix would be held in contact with the steel for a long time. I think where I'm at with this process is that I need to tweek the top shield some more. Maybe make it a little flatter, or wider, and move it away from the top of the receiver some- may 1/2" or so. This will force the water out further and extend the colors down the sides of the receiver more.

I'll post some pictures of tops so you can see what I'm talking about.

-jim
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Post by Jim D »

MDH,

Thanks for sharing your experiences! Can you post some pictures of your test pieces? Also, you might try a test with the air turned off just before queching and see if that affects your results.

-jim
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Post by Jim D »

MDH,

Suggestion:

Try screening your wood charcoal to get rid of the fine dust. I've found that the fine dust can obscure or block areas from being carburized and will result in areas that have Iron Oxide layer. This is different than areas that are just gray. Gray areas have the layer, but just didn't cool at the right rate to produce colors.

Questions:

1. Are the plates connected to each other as the y enter the quench? Even if they aren't, just by being in close proximity to each other will act as a form of shielding. Try marking the outside faces of the outside plates with a punch so that you can identify them, and see if the colors or patterns on these faces are any different than the inside plates.

2. What temp are you carburizing at, and for how long?

3. What temp are you quenching at?

4. What are the dimensions of your quench tank, how much water does it hold, and how far do the parts drop in the quench?

5. The colder the water is, the more Oxygen it will absorb. What is the temp of your quench water? How long do you aerate before quenching?
What PSI are you aerating at?

It sounds like you are taking a very scientific approach to this, and that will make you successful!! 1018 CCH's very well and you can get good colors on it. As you start experimenting with receivers I think you'll find that shielding becomes important. Thanks again for sharing your experiences, it's a great opportunity for all of us to learn from each other since everyone's methods and results will be different.

-jim
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Post by Jim D »

Darin,

Here's a photo showing the top of the '89

-jim
Image

The 1893 which I'm going to redo:
Image
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Post by MDH »

Jim;

The plates are not connected. Yes they are marked; I’ve got a numbering system that easily identifies location of each part. For example plate # 21b, denotes 2d set-up (where I changed one variable), first quench of that set up and second plate from the left. That way I can easily compare colors and see what impacts that one variable, proximity and location have on quench.

Carburizing at 1375, for 30 minutes, drop down to 1200 and quench.

Quench tank holds about 5 gals

I start the air when I fire up the kiln; not sure of the pounds per square inch (PSI) of my air flow; I’ll check the cubic feet per min (CFM) next time I quench, just lots of little bubbles.

I use 1018 steel because that is what I believe most early guns were made of. But I’ve also used 12L14 and some 8120 with good results.

Just did a solo fe cap with no shielding; came out great.

Anyway take care.
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Post by Jim D »

MDH,

Thanks for the info. I'm glad to hear that you are using safe and sane temps for your operation, and that you're getting good results! Please continue to share your results on this forum. It's good to hear what other folks are doing, and what works and what doesn't for them.

-jim
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Post by Jim D »

FIFTH TRY:

On this try I decided to make one shield for all of the receivers. The shield looks kind of like a fried chicken basket. The top of the shield is flat and goes into the quench first. (You're looking at the shield from the bottom.) The bent strips of steel hold the receivers a set distance from the underside of the shield so that the colors on top of the receivers will have more pattern. The strips also keep the receivers in relative position to each other as they enter the quench and cool. The sloping sides of the shield force the water out away from the parts as the shield enters the water. This is critical for forming good colors and patterns.

Image
Photo showing all the parts together inside the shield.
Image
Another Black Cloud:
Image
The results: (the two 1893s were part of this quench, the 1889 was done on the previous try. I re-did the bolt of the 1889 on this quench)
Image
Image
You can see the difference moving the receivers away from the shield has on the top colors and patterns. The 1889 from the previous quench is shown for comparision.
Image

The camera exaggerates the colors in the photos. In real life they are more subdued. They might look close to this in bright sunlight.

I probably won't be posting any more trys on this message board since it's down to minor tweeking now. I'll probably play around with the shielding some more, and the wood/bone charcoal ratio.

CONCLUSION:

I could not get any colors when trying to duplicate the same methods that Marlin used in "the film". From previous experince I knew the importance of some form of shielding to get acceptable colors and patterns, so I was not really surprised by the results of the first try. I had heard in the past that Marlin dumped the lid into the quench. The film didn't show this, but some of the events in the film were obviously staged, like putting crucibles in the oven with no lid, so it's hard to say what they did in actual practice.

On the second try, I made a sort of makeshift lid that sat over the parts inside the crucible. This produced colors, but coverage and patterns were not consistent. The receivers were not attached to each other for this try so they could go in random directions when they entered the quench. Also from previous experience, I knew that to get good results you have to control the direction of the parts, and how the water hits the parts as they enter the quench. Tries three through five were merely experiments with the shielding, with the receivers and parts restrained in order to control how they entered and fell through the quench water.

-jim
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marlinman93
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Post by marlinman93 »

Looks like you've prety much got it down now Jim! Those last ones all look super nice!
Again I'd like to say how much I've enjoyed this series you've shared with us! Best post I've seen on any gun forum!
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Post by Jim D »

Thanks Vall. I think it's down to the fine tuning now. From some of the photos of later guns, I think Marlin may have started using Potassium Cyanide in their mix. Sometime after the early 1900's the colors appear to have changed radically. I don't think I could ever duplicate those colors with just wood and bone charcoal.

I removed the post about wanting to catalog photos chronologically of CCH'd guns because it looked like it would be a major project and I didn't
get any responses A lot of collectors may not have the equipment necessary to take digital photos and post them. Getting photos of CCH'd guns to look right is difficult at best.

-jim
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