Metallurgical wood charcoal for fine blacksmithing?

A good neighbour of mine is an advanced knifemaker, producing functional works of cutlery/art that leave me in awe.

He is currently making hand-forged straight razors. Chatting the other day, he told me that he only uses wood charcoal (as the Japanese masters did) for this work. It's all about a precise, perfectly even heat. Metallurgical coal  and pet-coke have clinkers, hot spots and cold spots, which ruin these delicate blades.

This makes me wonder: given the mid-range native hardwoods I have, could I produce metallurgical wood charcoal?

I guess the first question is - what makes a good metallurgical charcoal? particle size, structure, chemical make up?

Does your neighbor purchase it or make his own?

Why use/make this if it:

have clinkers, hot spots and cold spots, which ruin these delicate blades.

Confusing to me.

Anne Miller wrote:Why use/make this if it:

have clinkers, hot spots and cold spots, which ruin these delicate blades.

Confusing to me.

This comment is about metallurgical coal (a selected grade of fossil coal) and pet-coke (a type of coke made from by-products of oil & gas refining).
And, is the reason why the neighbor/bladesmith uses wood charcoal instead. Wood charcoal doesn't contain sulfur, which is undesirable in steel, nor the many other contaminants present in fossil coal which create clinker and ash which make it difficult to maintain a clean, even fire for forging.

Douglas, surely you could. Whether it is practical or profitable would depend on how you were to go about it. As a curiosity-quenching exercise, and possibly an in-kind trade for your neighbor's work, it would probably be a memorable experience for you both! You couldn't put a price on that.

But, if you did want to put a price on it, then start by comparing your labor and materials to merely buying a bag of lump charcoal... you'd likely need to find a way to get multiple returns along the way for it to be "economical".  
If you needed to clear out some wood anyways, that's one, (maybe two, if you did it for hire).
You need to heat your home/shop/barn/greenhouse, so that's one (if you have a way to utilize the heat while making the charcoal).
If you have a need for by-products like syngas, wood vinegar, and wood tar, that's maybe one or two more... (run a generator, or "drive on wood" with a gasifier in your truck)
Maybe there's a way to combine making charcoal and smoking meats?

Some of the small scale retorts (inside of a regular wood stove) would be simplest to do, with little extra equipment or cost, and multi-tasking/function-stacking during the heating season.
Larger retorts, kilns, gasifiers, would all involve significant cost and effort, but would be more efficient or benefit you in others ways as well.

Crossed Heart Forge - YouTube , based in Vancouver, Canada, has many wonderful videos about making and using charcoal for forging museum-quality blades in the Japanese tradition.

Related thread from 11 years ago. I shoulda known.

https://permies.com/t/30487/Wood-Charcoal-Blacksmithing-Tips-Tricks

Kenneth Elwell wrote:Douglas, surely you could. Whether it is practical or profitable would depend on how you were to go about it. As a curiosity-quenching exercise, and possibly an in-kind trade for your neighbor's work, it would probably be a memorable experience for you both! You couldn't put a price on that.
... Some of the small scale retorts (inside of a regular wood stove) would be simplest to do, with little extra equipment or cost, and multi-tasking/function-stacking during the heating season.
... Crossed Heart Forge - YouTube , based in Vancouver, Canada, has many wonderful videos about making and using charcoal for forging museum-quality blades in the Japanese tradition.

Thanks, Kenneth. Excellent ideas! The link is also quite helpful.

Since I make biochar anyway, it's fairly easy to add a closed retort to the process using the existing heat. Until now I have not had a reason to do so. But I am always intrigued by the idea of the medieval village where artisans ply their craft within walking distance and use local materials.

If you're making it with a good hot flame cap process, the retort is superfluous (but handy if you have a special feedstock that you want to keep separate, like nut shells). The kontiki design is really just an incremental refinement of a centuries-old Japanese technique for producing charcoal for specialised metallurgical applications.

I think that for quality control I would want a lot more consistency in the feedstock, in terms of size and type, and more oven-like control over the cook-off. Unlike biochar, I think forge char would need to have a larger and fairly consistent chunk size to let air from the bellows through. It's not a big deal to put a small barrel inside a big barrel.

I have a cut-down and rewelded steel drum, about 70 litres capacity, that I can fill with whatever feedstock I want and toss into a kontiki burn about midway through the process. Works perfectly and makes very musical char. Take out one or both of the bungs, though.

Phil Stevens wrote:I have a cut-down and rewelded steel drum, about 70 litres capacity, that I can fill with whatever feedstock I want and toss into a kontiki burn about midway through the process. Works perfectly and makes very musical char. Take out one or both of the bungs, though.

Brilliant! I am envious. You have a good process.

My situation is not so neat and tidy. I am pulling all sorts of rubbish wood off the steep slopes of my property (by hand) for wildfire suppression. It's a mix of softwood and hardwood, at various stages of rot or not. Properly handled, it cooks into decent biochar, with two 55 gallon drums operating simultaneously. This generates a lot of small tinkly charcoal, and a lot of waste heat. To my mind, an experiment with chunked hardwood in a small barrel, amidst the rubbish inferno, would surely be worth trying.

That smith in the YouTube link I shared has a video or two about the size of charcoals. The raw charcoal he makes is limbs, sticks, lumber off-cuts, and not particularly usable as it comes from the retort/kiln. He goes though a process of chopping with a small cleaver to break down these larger pieces into smaller ones. The aim is to make as much of the "large size" chunks as possible, however poor aim, fractures, luck... will create smaller pieces, and even more smaller bits. He uses some screens to classify (four?) different sizes, which seem to each have a purpose in the Japanese forge tradition, so not a lot is wasted.
I would guess that used for agriculture, one would have even more use for the small bits than at the forge, and rather than going directly to crushing everything for soil amendments, screening out the forge sized chunks would be an easy first step.

Phil Stevens wrote:I have a cut-down and rewelded steel drum, about 70 litres capacity, that I can fill with whatever feedstock I want and toss into a kontiki burn about midway through the process. Works perfectly and makes very musical char. Take out one or both of the bungs, though.

Thinking it over, I like the idea of the two-stage burn -- it could give a lot of control.

I could build a foundation of junk-wood biochar in the barrel for heat, add the chunked "forge" wood on top, and move it to a portable firepit with a tight lid for finishing. I already have all this stuff at hand.