Coal/coke vs charcoal or wood

[reefera4m]

When I considered which solid fuel to use a I considered several alternatives, coal/coke, charcoal and wood (I didn't consider corn as it is not readily available here in the PNW and what with ethanol conversion the price is skyrocketing). I compared availability, price and efficiency. Until I found a cheap supply of coal I chose charcoal that I could make myself. I did a little research, talked to a couple of blacksmith who used coal and learned the following:

White pine has 2236 BTU per pound of wood, while white oak has over 4000. By comparison, charcoal burns at 9700 BTU per pound. And corn about 3600 BTUs per pound.
Unlike charcoal (which is charred hardwood) coal is a solid, black, rock-like hydrocarbon. Its stored energy is about 12,000 to 15,000 BTU and thus produces a much hotter fire using much less fuel than even charcoal. On a per pound basis charcoal can approach the lower end of coal BTU output. On a volume basis charcoal takes up 5 - 10 times as much room, coal being 5 - 10 times as dense. In practical terms a cantaloupe size chunk of coal has the same or more BTUs than a 5 gallon bucket of charcoal - first hand experience!

Any coal can be used for blacksmithing (bituminous coal is the most plentiful and usually cheaper, anthracite coal has the highest BTU). The main thing is the cleaner the better - sulfur being the worst contaminent. Most, but not all, coal that is available to blacksmiths is bituminous coal.

On a cost basis I found that it is hard to beat coal when you consider cost AND BTU's. If I don't consider the value of my labor, I can cut firewood the cheapest and make charcoal for just a little more. But when I do consider how much time it takes to cut, split, haul, stack, make charcoal, etc, then coal is by far the cheapest. .

There is also the consideration of the amount of effort it takes to maintain the heat. It takes me much less work to keep the forge fire going and at forging temp with coal than charcoal or wood (wood requires the most work).

I got real lucky and found a ton of coal on Craigslist (another thread). I knew what to look for and when I found out that the coal was being used in a coal stove inside a house I figured it was probably fairly clean. As it turned out it was excellent coal - very clean.

[chrisfrick]

Exactly what I've come to figure out. I originally started out using charcoal, as it was readily available from the local mega-mart in 10 lb sacks. Came out to about $0.85/lb (US). My wife's friend's husband used to be a blacksmith with his dad, who gave me about 10 lbs of coal to try. Been hooked ever since as I don't have to constantly shovel charcoal onto my fire, it gets hotter with less air blast, and I can get it for about $0.35/lb. I would make charcoal if I could, but don't have the space to do so (used to but hat's another story all together).

[Dragons lair]

While I run a gasser, I grew up with a coal furnace. Coal is NOT coal when it comes to smithing.
Heating coal can be used but if you want the best buy smithing coal or coke. I have to wonder at the #
given. 4000 btu per lb. So I get 16000000 btus per cord of oak. Cord is 4000lbs 128cu ft. Used to burn canal coal
about a cubic foot per chunk in furnace not forge.
Ken

[Robert Simmons]

Greetings,

I am currently building a Gas forge but I thought it would probably be good if I built a small solid fuel forge for the experience if nothing else. I gather that solid fuel forges heat more by conduction as the metal is in contact with the burning source where gas forges heat more by convection of hot gasses. However, coal forges are flat out of the question for me. I have asthma and hanging around coal and coke dust would do damage to my health, damage not worth a hobby. However, Charcoal is a potential option for me as it is far less dusty and easy to control.

So what I wanted to know was what are the essential differences between a coal and charcoal forge in construction, capabilities, gotchas and so on. As I imagine the earliest smiths used charcoal, I assume it is possible to do a lot of smithing work with charcoal, however, I don't know the first thing about using them other than that they follow some of the same basic ideas of air injection from the bottom.

Thanks in advance.

-- Robert

[edge9001]

Greetings,

I am currently building a Gas forge but I thought it would probably be good if I built a small solid fuel forge for the experience if nothing else. I gather that solid fuel forges heat more by conduction as the metal is in contact with the burning source where gas forges heat more by convection of hot gasses. However, coal forges are flat out of the question for me. I have asthma and hanging around coal and coke dust would do damage to my health, damage not worth a hobby. However, Charcoal is a potential option for me as it is far less dusty and easy to control.

So what I wanted to know was what are the essential differences between a coal and charcoal forge in construction, capabilities, gotchas and so on. As I imagine the earliest smiths used charcoal, I assume it is possible to do a lot of smithing work with charcoal, however, I don't know the first thing about using them other than that they follow some of the same basic ideas of air injection from the bottom.

Thanks in advance.

-- Robert

I used charcoal, as coal is just not reliably available to me. my forge is just a brake drum from my old wrecked van. the difference in charcaol vs coal. charcoal needs a deeper fire to get to welding temps, and ussually less air. I've een been know to forge while camping with the camp fire coals, although I don't recomend it...that gets hot, fast. as for the differences in construction, essintiallhy a charcoal forge is a coal forge, it seems to be al in how you use it. I would say just built a solid fuel forge, and practice with it. however....is asthma is a concern I would suggest sticking to the gassers.

[pkrankow]

Gas forges heat more from radiant heat than convection. Everything just isn't working until it is all glowing! Limiting your openings will help keep the nice glowing hotness inside.

After you get up and running, you may have an experience where your neighbor or postman notices the radiant heat off the forge opening from over 100 ft away.

Phil

[Grafvitnir]

I don't remember ever seen anything like this here so I'm adding the link for it. Is a charcoal forge with a very different tuyere.

http://mysite.ncnetwork.net/resr7g3w/other_stuff/blacksmithing/blacksmithing.htm

I'll like to know if anyone else have ever seen something like this.

Thank you

Rubén

[edge9001]

I don't remember ever seen anything like this here so I'm adding the link for it. Is a charcoal forge with a very different tuyere.

http://mysite.ncnetwork.net/resr7g3w/other_stuff/blacksmithing/blacksmithing.htm

I'll like to know if anyone else have ever seen something like this.

Thank you

Rubén

I've seen this before. Fromwhat I've heard it works great.

[Rob Browne]

Apart from making the fire deeper and using less air its also a good idea to have a couple of fire bricks to limit the width of the fire. Unlike coal, a charcoal fire will spread and burn your fuel without an air blast which is just a waste of fuel. If you limit the shape of the fire to match your work you will preserve fuel.

[reefera4m]

First, coke is just coal with the impurities burnt out. You can continuously make coke from coal - even while forging. Just place the coal outside of the burning coke and let the impruities slowly burn off (stay upwind). Once coal has been converted to coke it burns as clean as good charcoal and better than bad charcoal. The switch to caol was due to the depletion of available wood. Pretty much the same now, if your near a source of coal it can easily be cheaper that charcoal but if not, good charcoal can be homemade from a variety of wood. Just don't use chemically treated or painted/varnished wood.

As for coal/coke dust versus charcoal - not much difference. I use both (more coal/coke) and have seen as much if not more dust in charcoal as in coal/coke. Charcoal is much softer and more brittle than coal/coke and tends to make dust faster. It has less impurities that coal but the same or slightly more that good coke.

I've never seen a charcoal only forge. All the solid fuel forges I've been around have been used with both coke/charcoal.

[WildAtHeart]

White pine has 2236 BTU per pound of wood, while white oak has over 4000. By comparison, charcoal burns at 9700 BTU per pound. And corn about 3600 BTUs per pound.

All 100% dry non decayed Wood fiber have same BTU per pound. Its around 8660. Some woods are more condensed so people assume it has more BTU per pound but this is not the case. By weight all wood is the same however bye cubic feet the BTU amount varies from wood to wood.

[zampilot]

I thought hardwood burns longer but softwood burns hotter?

[beslagsmed]

Here in Denmark if you are smithing traditionally (viking) you use charcoal. Coal is readly available here, and very good stuff at that. I was to a friend's place in Portugal and we got some coal - was not so good, not washed, sorted or sized. I spent about an hour or so washing it so we got a better fire. Was suprised at all the rock we got in a bag as well.

[Fe-Wood]

I thought hardwood burns longer but softwood burns hotter?

Its an issue of density. Softwood has more room between the cell than hardwood. Softwood burns faster but not neccesarily hotter. A hotter burn really depends on the natural oil content of the wood... Think about dried sap from Pine