Ya thanks for the tip! I don't consider myself cheap but I like being frugal and Royal Oak is >$10 and no shipping. Your absolutely right Brownells is beaucoup pricey especially for the bone char. And you can just about double the shelf price to have it shipped across the border. I have mine dropped to my US mailbox in NY.

I still have most of a bucket of bone char as I don't use it for simple pack hardening. Straight wood with a 1/2 teaspoon of Potassium Cyanide per pack.

What are you sieving the Royal Oak to? 1/4" hardware cloth?

I hope you find your tubes of Polish O Ray. It's all I use followed by 555 grey to colour. 
Digressions are good, they lead to interesting places

Yes I follow you on the idea that a bollus Of fines enters the water as mass that creates a superheated shock void in front of it. Rather than multiple zones of exploding vapour   The discussion that was done at the the double gun shop alludes to this. 

I have made some charred leather and peach pits using the method you describe. Ha I did not use the mrs's Christmas cookie tin though. I found that clay pots with the optional water Base used as a lid makes a great " Coker" At a couple bucks each in multiple sizes They fit the bill

From prior: 
So the carbon surface is leached by the core metal of its available carbon, bumping the core to higher levels. But if you present carbonaceous material to the surface the surface will only absorb its normal process carbon percentage. the skin stays the skin!! If 2 hours at 1300 with XX media gives X surface change, re-casing allows process normalization to occur, dispersion of surface carbon back to "Uniform" levels and your stuck with "X surface" condition at quench. You cant double case, if you take the material to near a solution temp. its not cumulative. All that matters not. Everyone uses lower than solution temps to get color (almost everyone) where carbon absorption is minimal at best. For those desiring a deeper case, with potential for color, a sealed environment is optimal by a measurable margin, granule just doesnt matter,(especially if you add paper as I saw a couple folks do to sponge up the avail o2).

An interesting chart was developed with the 10 common materials used for case process. WOOD happens to be the HIGHEST GAS VOLUME PRODUCER in the common non-toxic stuff. So its not necessarily the WOOD chemistry in the wood/bone ratio that changes the color effect or case depth. Bone produces nil for pressure. Its a chemical provider,
but at the expense of gas volume. The wood makes the volume. I noticed that the bone is nearly always stated by the more experienced folks as a low number, wood being dominant. Nobody says WHY. I like the WHY. I will try to seal a vessel and see what happens. 

Frankly there are just too many variables for an experimenter to do, and still make a house payment and work. Sheesh. My electric bill, if I tried every option I have come up with or someone has stated, would be the National Debt.

So CHUNKY IS OK. FINE IS OK, except that it may tend to cause problems in the quench dump. I found it interesting. Its a complex response, not just a simple chemical reaction. Many aspects must be tuned to produce repeatable desired responses (if color and surface quality are at the heart of the process). Simple casing is just that, simple. Brearley is the author cited crudely above. OY!

The biggest reason that wood is the predominant component for US manufacturers is that it was cheaper.  If you look at the recipes for European and British case hardening, you will find that they are predominately bone, with most recipes 100% bone. 

What I believe Oscar Gaddy found, was that bone contains phosphorus, which when mixed with wood char, acts as an activator, allowing the steel to absorb the gaseous carbon more readily. 

My metallurgy instructor has been exchanging emails on a daily basis with me. I found out we are literally less than a mile from each other. He's a neighbor.

He produced a document regarding some British work.
MH is correct about 100 pct bone. Thank you Mike, all credit due.

I read it, and was flabbergasted. 

To prove a theory last night I made two successive runs on the same part. Poor think has been flogged with heat and no anneal. Beat the crap out of it I say.

I built a crucible inside of a crucible. That kept the char in constant contact thru entire quench. Results are basically a blued bit of metal. As deep a blue as one would want on a gun, nearly 100 pct coverage. I won't go into detail, the crucible had some design to allow limited and direct water flow to certain areas. This allowed me to contrast responses.

I have discovered the where and why of color formation. It concurs wih the Brit document. Now I must refine my crucible dimensions to allow the action to take place. It correclates directly with all of my results. It's not temp, it's not ratios,mist not necessarily water agitation, water temp,flow, no flow, etc. it's a very simple principle. Char mass.

My crucible is small, it's exactly the receivers dimensions plus 1/2 to 3/4 inch over size of part. Except my smaller receiver which is more dwarfed by the vessel.
The reason for mottled spottily performance is the bolus of char is not great enough in the quench tank at drop. The part must stay immersed in a fluid/vapor/char cloud for the process to occur. And must do so without inhibiting water flow, swirl, etc.

This was definitely proven in the last 3 runs made. I skimp on char as it's expensive. Can't do that. Vessel will need to be much larger to support the part and char needed for good performance.

There it is. Seriously. That's it. If you want to impart certain attribute you can add stuff to keep char closer to the metal during quench, say a blue stripe, etc. but water must still flow and char must disappear. Just slower than the balance of the part.

I'll be back with results on my warped, cracked, beat up receiver. It's a perfect specimen to use. A block of metal will not give the same real world results that this hollow chunk will. It presents all the variables. I have to keep using it.

One more thing, polishing past 400 is futile. I did fire up the buffer and so,e POR up to 400. I also used s/s carding brush on another run. The 400 looks better. 600 will not hold up.

Seanmp wrote on Apr 23^rd, 2015 at 10:45am:


Everything I've ever read has said results were poor if you try to reuse it.