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Posted by Martin H. Eastburn on January 26, 2010, 7:01 pm
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Let's look at the materials.
1. vermiculite is mica. Mostly Muscovite or the old name Muscovy from th=
e Ural=20
mountains in Russia. It is classified into Phyllosilicates in mineralogy=
=2E
2. dry ashes - or mud if water within. Dry is really water driven off an=
d dry.
Therefore when vermiculite is used it is a large array of sheets of miner=
al and
hold lots and lots of moisture. It is hygroscopic as I recall.
The ashes are void of air and moisture keeping scale down and blanket of =
pre
burnt material. It withstands most any temperature until it converts a r=
efined
state of minerals.
Likely had steam cooling in the vermiculite.
I've heard of both, and this test you did was good input.
Martin
spaco wrote:
> Some years ago I published in The Metalsmith, a test I ran cooling a=20
> chunk of steel in my ash bucket. Last week I ran a very similar test=20
> using vermiculite instead of the ashes from my coal forge. I was=20
> shocked to see that the part cooled much faster in the vermiculite=20
> (about 600=B0F in the first hour)than it had in the ashes (about 300=B0=
F in=20
> the first hour).
> Does anybody here have data that would support or refute this finding=
?
> I did find one blacksmith related site where the guy said about the sam=
e=20
> thing, but his experience was apparently anecdotal.
>=20
> For what it's worth, either annealing medium will work pretty well for =
> plain carbon steels, and maybe for 4140. But it won't do much for even=
=20
> 01 let alone S7 or other air hardening steels.
>=20
> I already have the "ashes" test data and graph on blacksmith portion of=
=20
> my website and I will make a page for the vermiculite results if some o=
f=20
> you are interested.
>=20
> Pete Stanaitis
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