Recipe for Kasenit

[singleshot]

YOD- That was Colt's blueing process you saw. The hardening was was a bone /leather/charcoal (willow) pack process.

Willis Gregory

[Black_Moons]

Kasenite is straight sodium ferrocyanide. It produces a carbo-nitride case. Sodium ferrocyanide is available as a food grade additive used as an anti caking agent in table salt but you would probably have to buy a 40 kilo bag if you can find a supplier. It goes by the name yellow prussiate of soda so as not to scare people.

lol at chemical euphemisms. Then again, I doubt id want to eat sodium ferrocyanide either.

[JCHannum]

YOD- That was Colt's blueing process you saw. The hardening was was a bone /leather/charcoal (willow) pack process.

Willis Gregory

Agreed, it is carbona or charcoal bluing. It was used by many manufacturers prior to WWII, but has fallen out of use since. Doug Turnbull and a couple of other restorers of fine firearms have the service available.

[Mcgyver]

YOD- That was Colt's blueing process you saw. The hardening was was a bone /leather/charcoal (willow) pack process.

I agree with you guys the pack method with the right stuff will produce the colour caseharding....but there is another way. In high school, grade nine machine shop, we made what every budding machinist needs in his kit, the venerable tack hammer.

The heads we case hardened in the shop. There was a cylindrical oven/vat that was full of some molten material, salts of some sort iirc and the resultant finish on the heads was spectacular, like the best starrett surface gauge or firearm. I remember our shop teacher explaining we could sand it shiny again however that the finish was highly prized by many metalworkers.

I can't remember what the process was --- anyone know? It dispelled the myth that the colour case has to come form a stinking pack of secret recipes...all 20 of us 14/15 year olds did it just fine in Mr. Dittmar's red hot soup...but i hazard a guess that soup and what fumes it emitted would not be something you'd want around the house!

[JCHannum]

Mike, that would have been cyanide salts. It also was used by many for color case hardening. Dip & quench in water to get the color. Needless to say, it has its drawbacks and has lost favor today.

[lazlo]

The beautiful random coloration they got came from have the parts suspended in an overhead trolley about 8 feet in length and the charcoal fire mix in the pit below.

From what I've read on the blacksmithing forums, the beautiful colors come from organics in the carbon source. So leather, bone char et al ostensibly have it, and pure carbon theoretically wouldn't.

There's a famous gunsmith that posts in these case hardening threads from time to time, and he mentioned they use a (secret) mixture of bone char and wood charcoal. Translating with the above, I would guess that the different organics give the blues, yellow, reds that are so desirable.

Then there's cyanide salt baths, which Jim mentioned. I remember reading an old Starrett catalog that indicated that's what they used, and that process also gives you beautiful colors, albeit not nearly as jaw-dropping as the old-school gunsmith recipes.

[Evan]

Curious to know what the other 54% are and whether they affect the transfer of carbon even thought they are non msds controlled??

The balance is non toxic salts, either sodium chloride or potassium chloride.

From what I've read on the blacksmithing forums, the beautiful colors come from organics in the carbon source. So leather, bone char et al ostensibly have it, and pure carbon theoretically wouldn't.

Yes, it is the organics. They form a nitride coating of varying thickness which is responsible for the colours seen. Just like the varying clours of oil on water the thickness causes destructive/constructive interference that allows only certain colours to be reflected. Of course plain carbon doesn't contain any nitrogen.

It is exactly the same effect that produces the various colours on plain steel when it is heated although the oxides of iron coating isn't nearly as durable.

Example:

[.RC.]

http://users.beagle.com.au/lathefan/...0hardening.pdf

[lazlo]

Wikipedia's explaination of the chemistry of Color Casehardening. Apparently pure carbon as I was suggesting above would be painfully slow -- bone char, leather et al have various forms of chemical accelerants like barium carbonate in Guy Lautard's Bullseye Mixture:

Chemistry

Carbon itself is solid at case-hardening temperatures and so is immobile. Transport to the surface of the steel was as gaseous carbon monoxide, generated by the breakdown of the carburising compound and the oxygen packed into the sealed box. This takes place with pure carbon, but unworkably slowly. Although oxygen is required for this process it's re-circulated through the CO cycle and so can be carried out inside a sealed box. The sealing is necessary to stop the CO either leaking out, or being oxidised to CO2 by excess outside air.

Adding an easily decomposed carbonate "energiser" such as barium carbonate breaks down to BaO + CO2 and this encourages the reaction

C (from the donor) + CO2 <—> 2 CO

increasing the overall abundance of CO and the activity of the carburising compound.

It's 'common knowledge' that case-hardening was done with bone, but this is misleading. Although bone was used, the main carbon donor was hoof and horn. Bone contains some carbonates, but is mainly calcium phosphate (as hydroxylapatite). This doesn't have the beneficial effect on encouraging CO production and it can also supply phosphorus as an impurity into the steel alloy.

[lazlo]

http://users.beagle.com.au/lathefan/...0hardening.pdf

Thanks Ringer -- that's a great article! That confirms the carbon + (barium) carbonate accelerator. What's "Whiting Powder"?