[TheForge] Stoker Coal

[Dave Brown]

>n addition to my regular forging coal I still have an ash can or two of
>the stoker coal that I was given when I first started and a customer
>wanted to clean their bin.
>
>I will probably still own it when I die. Mine is usable. It is also a
>sulphurous clinker laden PITA.
>
>Your may be better try it.
>
>Mike Graf

There are all sorts of grades of "stoker" coal.  The word stoker refers to 
a particular size range for the pieces of bituminous coal the same as "nut" 
or "pea" refer to sizes of anthracite.  If possible, you need to get the 
specs (i.e. typical analysis) of the particular coal you are going to 
use.  Stoker coals typically run at about 28% volatile matter (VM), but it 
ranges from a bit above to a bit below this level.  The lower the volatile 
matter, the better the coal.  Pocahontas #3 at about 15% VM is more a 
"semi-bituminous" coal.

You also want to look at the Free Swell (FS) <aka coke button>.  You want 
as high a number FS as you can get (range is 1 to 9+).  Mostly you will 
find that stoker coals are in the middle.  For example Pocahontas #3 is 
around a 7 or 8, whereas Cumberland Elkhorn (a popular 'smithing coal) is 
around 4 or 5.

There's a lot more stuff about smithing coal, but the VM and FS are the 
most relevant.  If you want to know more, just let me know and I'll write a 
small treatise on the matter (volatile and otherwise). :))

Dave Brown
Heritage Smithing
Green Bay, WI


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