Coal Forge : "Best" size for coal pieces : is there one?

[John Fly]

Fire building / starting up a coal fire, is often discussed, but I've
never heard anyone comment on the actual size of the coal "lumps" used.

I never really pay much attention to it, I just take a bucket full and
dump it on the fire :)

But is there any reason to prefer large coals or small coals?

[Trevor Jones]

There may be a reason to prefer one or the other, but in the scheme of
things, it's use what you can get.

I learned coal fires using fines and screenings. It was what was
available.

I gotta say that the first time you start setting up to make a coal
fire, in front of somebody new, by pouring a couple scoops of loose coal
on the table of the forge and dumping a couple cans of water on it and
mixing it into black mud.... Well, They look at you kinda funny!

Cheers
Trevor Jones

[JayBee]

Trevor - I cant disagree that we have to live with what we can get, but...

In an ideal world <g>, what would be best?

As a complete newbie who has yet to start his first fire or buy his
first bag of coal, it would be good to know what I'm REALLY looking for,
even if I have to settle for 'anything that burns'!

Jay

[Ken Rose]

JayBee wrote:
> Trevor - I cant disagree that we have to live with what we can get, but...
>
> In an ideal world <g>, what would be best?
>
> As a complete newbie who has yet to start his first fire or buy his
> first bag of coal, it would be good to know what I'm REALLY looking for,
> even if I have to settle for 'anything that burns'!

Personally, I like it fairly uniform, and maybe about 3/4 of an inch
across or so. Recently, I've been using the black mud with occasional
boulders. It's a pain, but it does burn.

- ken

[spaco]

I'd say that thumb sized pieces of coal are about the largest that you
want, with some finer stuff. That makes it easier to mound up and shape
the fire. Also, I think the smaller stuff makes coke that is more compact.

Pete Stanaitis
--------------------

[spaco]

Pocahontas #3 is a good metalurgical grade coal. It is used, in larger
sizes (3 inch or so) in steam boilers. We used to get it from a yard
that sold it for that steam boiler purpose. Once the bunker was down to
about 2 feet deep, that became the "blacksmith coal", since it was
mostly smaller pieces.

Find a blacksmith club close to you and ask them where they get theirs.
Our club buys 20+ tons at a time and resells it to members.

Pete Sanaitis

You want a coal high in BTU content and low in ash and other impurities.

[trahern]

Well...it depends on what you are trying to do. normally I prefer
fines because with a piece of 2x4 lumber I can form fines into an oven
for welding or heat treating by packing fines around it. And if I had
a choice I'd take the fines every time. Reason? I can forge with fines
but I can't make an oven with lump coal. Plus I think the burn rate of
fines is a bit slower because the flames can't whistle through the gaps
and expand so quickly.

[Trevor Jones]

JayBee wrote:
>
> Trevor - I cant disagree that we have to live with what we can get, but...
>
> In an ideal world <g>, what would be best?
>
> As a complete newbie who has yet to start his first fire or buy his
> first bag of coal, it would be good to know what I'm REALLY looking for,
> even if I have to settle for 'anything that burns'!
>
> Jay

Have you actually tried to find a supplier that has a selection (or
any) metalurgical coal? Like good steam coal, it was once common, but
now is not. In an ideal world, we would be picky. In our present world,
picky means doing without. What you are REALLY looking for is coal. Coal
suitable for smithing, preffered, size optional.

If you find a supplier that has any coal at all, ask if they know the
composition. Chances are beyond likely, that they will look back at you
like you are thick, and repeat to you that it contains coal. In the
unlikely event that they actually know it's composition, low ash content
and low sulphur are preferred. There are ratings for BTU/pound, but
outside of the odd mention in live steam circles, I've not seen them
used.

You can also forge with charcoal, and I have read of guys using green
oak, broken into fairly fine chunks as fuel.

From my view, use what can be got. Chunks can be broken to fines, and
fines can be mixed with water and coked into large chunks if required.

I have managed to forge weld with some truly poor quality coal
(shoveled off a pile at a lime plant) that required a coordinated effort
between the cranking of the blower and the fishing of large chunks of
clinker from the firepot whilst loading more fuel into the fire pretty
much simultaneously. I estimated at the time that I got about half as
much clinker out of the fire as I put in coal. It's less stressful to
use nice clean hot burning coal, but that was what was there.

Cheers
Trevor Jones