Color case hardening

[Phil Coffins]

My apprentice doing the quench. Thought it may entertain you click to play video.

MVI_0507 by Oliver Sudden, on Flickr

 

[Tom A Hawk]

Details please. Bone meal? Temp? Time at temp? What was used as a container? Closed container or left open? Results?
Doug Turnbull, who does some of the finest color case hardening, has a shop about 20 minutes from me.

 

[Phil Coffins]

My containers are thin steel tubes with a steel plate welded on for a bottom. As a lid I just set a steel plate on top making sure the pack fills the crucible. Wood and bone charcoal is mixed at the rate depending on how I hope to make the color. These parts were done at 4 to 1 mix heated to 1400f for one hour then brought down to 1375f till stable. Plain water quench was 50f that was aeriated prior to quench for two hours.

IMG_1099 by Oliver Sudden, on Flickr

 

[Buckskinn]

Those came out perfect!

 

[Tom A Hawk]

Great job. Thanks for the details. Gas forge or coal? I see a half stock Hawken in your future.

 

[dd832]

Excellent work on those Hawken parts (Pedersoli?) Phil ! Thanks for posting those videos too, it is nice to have someone assist when moving the canister to the quench bucket. Are you using an electric heat treat oven?
Mike

 

[Phil Coffins]

Thanks. These parts are for another guy that I don’t know. He sent the parts to me to case. Yes, I use an electric furnace.

 

[M. De Land]

If one has trouble with getting wood charcoal to mix with bone(hazmat) , as I do in Alaska, I have found that coconut charcoal from water purification stores seems to work just as well from the several times I have tried it.

 

[1861colt]

I have understood that running a tight spiral coil of copper tube with a lot of little holes placed in the bottom of the tank attached to a compressor running at time of dunking will flood the water full of air bubbles that will put on a tighter multi color pattern. Has anyone tried this?

 

[Phil Coffins]

I did the coil thing at first but now just use an aquarium type bubbler with equal success. A couple of times I did a small part in a five gallon bucket. Water was poured back and forth between two buckets just before quench and the results were just as good.

 

[1861colt]

Amazing what works, huh. One video a guy believed it came out better if done in an iron box with sliding lid, when done, flip over and pull out lid from under so it all falls in at once.
When you say 4 charcoal to one bone gets what you want, what do different mixes give you for pattern or colors.
Click on my avitar and see this is what I was talking about. I love the pattern.

 

[Phil Coffins]

Yes I do different mix’s. If you search some of my posts you’ll see a few examples.

 

[1861colt]

I will take a look. What do you coat the parts with to put a protection on the surface.

 

[Phil Coffins]

I've always used gun oil. This one I did years ago.

IMG_0400 by Oliver Sudden, on Flickr

 

[1861colt]

Now that is gorgeous. So much better looking than what you get from the Cimarron or Uberti guns. They don't believe in a good polish to the parts to give a pleasing result either. My old Replica Arms looks better than I have ever seen these guys do.

 

[M. De Land]

I use an aquarium bubbler as well. What your after is dissolve oxygen in the water not the bubbles per seh. I put the bubbler on for 15 minutes to half an hour before the quench then shut it down just before the drop.
Differences in steel alloy, quench temperature , wood/bone ratio , drop heights and amount of charcoal around the target piece all influence how it will come out. Other techniques that effect pattern of color are wire or bolt attachments to the target piece which hold the charcoal to the piece during the quench drop. Also using old quench water mixed with new distilled water will enhance color.
Blocking parts is important as well to minimize distortion that will occur to some degree with any case hardening.
Another tip I like and use is to allow the crucible to rest for a full two minutes after it comes out of the oven before quenching.
Sun light makes case coloring fade fast and I have found a coat of True oil over the case color surface to preserve it very well.

 

[1861colt]

Well, I guess I see now that my 1861 is chemically colored, but is sure is pretty anyway, The factory put some sort of finish over it and it doesn't chip off or fade. I sure wish I knew what it was. With the real process creating feathering around holes and edges makes every part have it's own personality.
So what is the blocking technique for thin parts that was mentioned. There apparently is a talent to packing the 'suitcase'.

 

[Roughneck]

Beautiful job!!

 

[M. De Land]

Mortises usually have a snug fitting steel block drilled full of holes or I-beam block in the mid section to keep them from warping inward. Thin straps will often be bolted through purchase holes to a stiff piece of angle iron. Lock plates are similarly blocked and Tangs need the same treatment. Small parts are usually wired together or fastened to a tree by wire to keep them together in the quench drop.
Some very nice case color can be made by wrapping a receiver with heavy black iron wire positioning the coils open enough for the charcoal to escape as it falls down through the quench.
The target parts need to be packed in the mixed wood and bone charcoal with all air removed then tamped down.
I use rectangular crucibles because they seem to make more uniform patterns for me instead of end drops from steel tubes.
There is a bed of charcoal put in the bottom at least 3/4 inch deep. It's packed down and the parts are arranged on this bed with a least 1/2 to 3/4s inch room between then all the parts, including interior cavities, are filled and packed with charcoal and tamped down. The parts are covered with another 3/4 inch of tamped down charcoal and the lid is put on. The lid is not air tight as the gas from burned charcoal needs to vent off but it should fit snugly and have a rim so it won't slide off when the heated crucible comes out of the oven and needs flipped over for the quench drop.
The flat lid of the crucible drops off and moves the surface water out and around making the quench come in from the sides which is the least shocking position for the hot steel to hit the cool quench water.

 

[M. De Land]

One more technique I like to use is to sand blast then glass bead the surfaces after they have been trued and cleaned up to be case colored. This textured surface makes for a more durable case color that stays on better than on a smooth surface. It also knocks down some of the bright and gaudy glare that are not really present on traditional coloring. It needs to be remembered that the purpose of case hardening is one of strength not pretty colors, which is a nice bi-product but not really useful from a strength and longevity prospective.
For really deep casing one needs a lot higher temperature but color will not manifest as well at much over 1450 F or so in my experience.
These lower temperature charcoal/packed case jobs are usually only a couple thousands deep but that is enough for black powder use which is in the same neighborhood as shot gun pressure , also usually thinly cased.