doublegunshop.com - home Forums General Discussion DIY Gunsmithing @ doublegunshop.com color case hardening

I usually get the pack up to 1350 degrees F and hold for 1.75-2 hrs. I then drop to around 1150-1100 degrees F and try to stay there for 30 minutes. I think that this was a 2:1 wood to bone charcoal mix. I have changed the ratio around when I was doing a little Winchester rifle and small parts. Lid is fairly tight but the pack is full covered in coal and I usually put a piece of paper under the lid that often times doesn't even burn completely since there is not much oxygen after a slight flash burn that uses it all up at that high of a temp. I had a plate that was bolted on the front of this receiver that hit the water first which helped cause a splash and helped maintain coal around the parts. My quench tank is probably a 45 gallon drum barrel that is about room temp or less. I've tried using ice to cool down but didn't notice much of a change. I don't reuse any coal unless I am annealing. There is probably 3/4 in of coal around the receiver in the crucible which I think is one of the problems and why I am building a larger oven. The crucible is rectangular tubing with a hinged lid. I don't block. All I do is have a spacer that fits between the tangs and between the side plates. My main reason for wanting a cage or fixture for holding the receiver is that it will cause greater movement of water and hold the coals in a way that will allow consistent results if all other variables are the same. I learned a lot from the marlin thread about a year ago when I first saw it and a link was posted above but haven't seen much on sidelock shotguns. Thanks, Zachary

Now I have never tried to colour case harden though I have used commercial case hardening products. Given that I have collected snippets of information on colour case hardening mixtures over the years especially the little additions to the basic bone and wood charcoal mix. Some of you folks who colour case harden may like to try some of these extra additions. As far as I know they are all forms of carbon but with various trace elements and should not cause any strange effects other than improving the final colours of the finished article.
1 Carbonised Blood Fish and Bone garden fertilizer. Made by roasting in a tin keeping the air out with just a small hole to let the fumes escape, keep heating until totally converted to carbon.
2 Carbonised leather made by treating as Blood Fish and Bone. Traditionally a small amount of Ivory turnings where also added. But we all know that Ivory looks far far nicer on elephants so that is a no no, though there was a substitute recommended which was crushed sheep�s teeth.
3 And to improve the surface hardness it is recommended that a small quantity of Potassium Ferricyanide is added to the final colour case hardening mixture before use.

***** Even though the name is similar to its extremely poisonous big brother Potassium cyanide, it has a low toxicity but can be an irritant. *****

Keep the Air blowing through the quenching tank all the time. This causes uneven cooling effecting the final colour pattern, and Potassium Nitrate I have already mentioned.

Colour case hardening is �all steam muck and magic� improved by lots of practice.

Gun Craft by Venters is a very modestly priced book that has a case color section. Like most, it's not highly detailed, but shares plenty enough times, temps and misc. comments. On the other hand, if a lever rifle works slick after case coloring, then those techniques may be sound. Thanks for sharing what you have done.

you have to aerate the water all the time. you have to break up the steam envelope,and let the pack cool before dumping in the tank i think your temp is to high, if you try and make your own bone charcoal make sure you neighbors are not down wind from you.on your crucible seal the lid and add the piece of paper to use up any oxygen.i have made several crucibles,most like dr gaddy but i do have a short one i used for SAA frames.good luck there are a million different ideas on how to make this work,you have to figure out how to make it work consistently.

PA24 recommended adding pieces of hoof to the pack, on the edges of the crucible. This might serve the same function as the ivory or teeth.

My own tests have been unsuccessful, I'm getting unacceptable scaling, but with small patches of nice color. Since I've been making my own charcoal I suspect it hasn't been cooked completely, causing the contamination. On one test I had sealed the crucible with hearth cement, but during the heat I heard a "pop", and when I opened the kiln there were flames coming out of the crucible along the edge seam of the lid. I've ordered charcoal from Brownell's to see if I'm right. Anyone have any insights?

Regards
Ken

damascus,

You've spelled them both the same. Is this correct?

Searching thru my old garage junk I came across Dr Gaddys #2 article on case coloring,as It is very detailed article with photos,It explains Lc smith Colors parker ect.Over the years I have tried everything in quench tank, such as stuff that you wash cows feet with,Just throw all that stuf out,and followed Gaddys article,wood and bone , buy it from Brownells

I think, if you get patches of color and some true scale forming, then maybe some of the steel was protected from oxygen (formed colors), and some of the steel was exposed to oxygen (scale) when it was in the higher temp. range. I would guess that your crucible made it through the heat cycle, and maybe O2 is reaching the parts during your quench.

Just the flames that you saw may not mean anything by themselves. If the material was up to temp and air got in if the cover moved, chances are it would show a flare up.

I would think the main reason to use known materials would be to minimize the chance of surprises. If you have the Venters, Gun Craft, book, R. Brown makes mention of how they cook their materials to burn off possible impurities. He also thinks if the technique is sound, that flaking is oils either from inadequate cleaning or residual in the charcoal.

Only thoughts Ken, best of luck with it.

Thanks Craig.

So many variables. Besides the charcoal issue, it may be quench procedure. My crucible is fairly large, holding around 1 1/2 gal. Of medium, it's designed to hold two actions. My test pieces have been unblocked lockplates. So, even though I am able to flip the crucible quickly over into the quench, there may still be oxygen getting to the pieces. I also may need a longer heat time because of the crucible size.

Since I'm now waiting on Brownell's, I'll construct the blocking rack to fit inside the crucible.

Great thanks to the members who have recently sent me Part II of Dr. Gaddy's article.

Regards
Ken

Hey Ken, that's a pretty large crucible. You may be under filling it to save on the charcoal materials.

Consider making up smaller crucibles out of black pipe or thick wall square tubing. It's not a big deal to weld a flat base on the bottom, and rig up a slip fit welded square cover, or use a die grinder to clear out the threads of a screw on cap for round pipe.

I think I've mentioned before that you can cut V's off of angle iron quickly with a chop saw and weld them to the sides where ever you want so the crucible doesn't slide with whatever you hold it with. You can burn off paint and oil with a torch before you run it in your kiln.

I think fill the crucible, tap it down, and fill some more in. Careful this time of year, there's a bunch of CO produced that might not be venting off.