My buddy Ron has been building a Hawken rifle with some guidance from this geezer, and it's turning out really nicely. He wanted to colour case harden his iron hardware, and since I didn't do that to my own rifle, we polished up both sets of furniture. We used straight hardwood charcoal for the first attempt, and we got quite satisfactory results. But this time we wanted to try adding both bone charcoal and leather charcoal to the pack. I had a steel crucible made out of 5/16" walled tubing about fifteen inches long, with a cap welded to the bottom and a loose fitting lid for the top. Into this we poured garden variety bone meal to the top, and set it in our fire to cook. It took quite a while...well over an hour but finally, the gasses stopped issuing (flame went out) and we removed it from the fire to cool overnight. We got lovely charcoal. Now we packed the crucible again tight with pieces of leather and again, cooked it to make it into charcoal. The result was interesting: whereas the bone meal did not shrink appreciably, the leather reduced to about a third the volume, and this I crushed with a wooden pole. In a clean plastic bucket we poured all of the leather char, all of the bone meal char and about twice that volume of wood char, and mixed it up. Now we packed two other crucibles, each made from diesel truck exhaust stack steel pipe - about 4 1/2" in diameter with the char mix and our parts standing on their ends, none touching the pipe or each other . Both of these obviously have steel bottoms welded on, and a loose fitting 1/2" thick steel cap. Several days ago, Ron and I made some 'tongs' out of rebar steel, for placing and removing the crucibles to and from the fire.
With the crucibles ready for firing, we made a hot fire in his backyard burning pit (pictures to follow) and when it was coals, we made a flat spot for each of the crucibles and set them into the pit. Now we built up the fire with birch firewood, and within fifteen minutes had our crucibles at red heat...lids and all. We sustained this fire for two full hours.
In the meantime, we made an aerator out of 3/8" flexible copper tubing, hooked up a compressor to it, and placed it in the bottom of a big garbage can. We filled the can with cold water, and turned on the air, letting it bubble while the fire did its thing.
At the end of the two hours, we opened the fire, clamped on to each of the crucibles in turn and dumped them into the water.
The results were far more dramatic than our first attempt. The colours are more varied and interesting, and much brighter, and the surface is very hard...a file simply skates over it. We placed the parts in a common toaster over with an over thermometer and once a steady 375 deg. F. was achieved, we soaked the parts at a steady heat for one full hour. I think that his intensified the colours and added some yellowish straw colour to spots that were first rather grey and boring.
Here's a short story in pictures...
This is Ron (left) and brother Daryl (right) staying cool and hydrated, sort of...
Here, you can see a crucible at red heat in the centre of the fire.
Here' Ron is removing one of the crucibles and within a few seconds, inverted the pot into the water. We were careful to make this happen with the least amount of oxygen exposure possible. The sun has moved around to the fire pit, and though it may not look like the crucible is hot enough, it is at red heat for sure.
The parts gathered from the bottom of the can, cleaned off with fresh water.
A close up...
