Marcia Selsor on sat 19 apr 03
yes Paul and the catalog price is a dollar /pound difference.
marcia
Paul Lewing wrote:
> I have a question about Spanish Red iron oxide too. I bought some from my
> local supplier and it was a dull, almost maroon, red unfired. In using it,
> I saw no difference between the fired result of it and regular red iron
> oxide. Later someone told me that real SR is very bright orange when raw,
> and that what I'd been sold wasn't it. Is this true?
> Incidentally, this is the same supplier who someone else reported having
> told her that SR and Crocus Martis were the same thing. I also have some CM
> from them, and if does indeed look and fire just like what they sell for SR.
> Paul Lewing, Seattle
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
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>
--
Tuscany in 2003
http://home.attbi.com/~m.selsor/Tuscany2003.html
Paul Lewing on sat 19 apr 03
I have a question about Spanish Red iron oxide too. I bought some from my
local supplier and it was a dull, almost maroon, red unfired. In using it,
I saw no difference between the fired result of it and regular red iron
oxide. Later someone told me that real SR is very bright orange when raw,
and that what I'd been sold wasn't it. Is this true?
Incidentally, this is the same supplier who someone else reported having
told her that SR and Crocus Martis were the same thing. I also have some CM
from them, and if does indeed look and fire just like what they sell for SR.
Paul Lewing, Seattle
Ellie Blair on tue 22 apr 03
Has anyone used spanish red iron oxide in crystalline glazes? I have =
been getting some strange results and I have narrowed it down to the =
only common factor in the pieces is the oxide. The glazes are staying a =
matte and not forming crystals firing to 2350 dropping the temp to =
between 1950 and 2050 and holding for 3 hours.
Ellie Blair
Mac and Judi Buchanan on thu 24 apr 03
Ellie, My results with RIO in crystalline glazes is just oposite yours.The
glazes are clearer and more crazed with fewer crystals with even small
additions . Boy, are these glazes hard to get a handle on ?
Judi Buchanan
Has anyone used spanish red iron oxide in crystalline glazes? I have been
getting some strange results and I have narrowed it down to the only common
factor in the pieces is the oxide. The glazes are staying a matte and not
forming crystals firing to 2350 dropping the temp to between 1950 and 2050
and holding for 3 hours.
Ellie Blair
____________________________________________________________________________
__
Mac and Judi Buchanan on thu 24 apr 03
Ellie, I'm using a high quality RIO. I can tell it is stronger and finer
quality than usual in my other non-crystalline glazes. If I were you I'd
check the Spanish in an iron glaze that I was really familiar with to see if
there are any changes in that glaze. It seems to me, small particle size and
stronger concentration of the metal would ordinarily give a stronger color
and be more refractory and I can't think of a contaminant that would cause
as great a change as you describe in the small amount used as a colorant.
Judi
> Is the oxide you are using just RIO or is it the Spanish RIO. There is a
> difference. The Spanish is a lot finer particle size. My supplier told
me
> it was a purer form. I don't know about that though. I get the same
results
> as you with just RIO.
>
Ellie Blair on thu 24 apr 03
Mac and Judi,
Is the oxide you are using just RIO or is it the Spanish RIO. There is a
difference. The Spanish is a lot finer particle size. My supplier told me
it was a purer form. I don't know about that though. I get the same results
as you with just RIO.
Thanks
Ellie
----- Original Message -----
From: "Mac and Judi Buchanan"
To:
Sent: Thursday, April 24, 2003 1:14 AM
Subject: Re: Spanish red iron oxide
> Ellie, My results with RIO in crystalline glazes is just oposite yours.The
> glazes are clearer and more crazed with fewer crystals with even small
> additions . Boy, are these glazes hard to get a handle on ?
> Judi Buchanan
>
>
> Has anyone used spanish red iron oxide in crystalline glazes? I have been
> getting some strange results and I have narrowed it down to the only
common
> factor in the pieces is the oxide. The glazes are staying a matte and not
> forming crystals firing to 2350 dropping the temp to between 1950 and 2050
> and holding for 3 hours.
> Ellie Blair
>
>
____________________________________________________________________________
> __
>
>
____________________________________________________________________________
__
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
>
Ellie Blair on fri 25 apr 03
Judi,
Thanks for the input. I will just keep experimenting until I find out what
is causing this effect.
Ellie
----- Original Message -----
From: "Mac and Judi Buchanan"
To:
Sent: Thursday, April 24, 2003 9:23 PM
Subject: Re: Spanish red iron oxide
> Ellie, I'm using a high quality RIO. I can tell it is stronger and finer
> quality than usual in my other non-crystalline glazes. If I were you I'd
> check the Spanish in an iron glaze that I was really familiar with to see
if
> there are any changes in that glaze. It seems to me, small particle size
and
> stronger concentration of the metal would ordinarily give a stronger color
> and be more refractory and I can't think of a contaminant that would cause
> as great a change as you describe in the small amount used as a colorant.
> Judi
>
> > Is the oxide you are using just RIO or is it the Spanish RIO. There is
a
> > difference. The Spanish is a lot finer particle size. My supplier told
> me
> > it was a purer form. I don't know about that though. I get the same
> results
> > as you with just RIO.
> >
>
>
____________________________________________________________________________
__
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
>
Tom Buck on tue 29 apr 03
Yes, John,
I will chime in. The following is what I learned many years ago
when I did some articles on bacterial mining (the Canadian application was
recovery of uranium from abandoned hard-rock mines). Such mining began in
Spain long ago, and as far as I know the mine still is in operation.
There are at least 20 separate names for iron oxide red either
occurring in nature or slightly upgraded from a mineral deposit. This
mineral is impure Iron(III) Oxide which chemists now use as the preferred
name for "Ferric Oxide" nowadays).
In Spain, there exists one large orebody assaying low amounts of
iron sulfide (mostly), too inadequate for steel-making even with modern
"float sink" technology. Long ago, however, an astute person noticed that
rainwater would pool, then evaporate and leave behind a mineral that
turned red on roasting. In time, it was discovered that a specific
life-form (a bacterium, named bacillus ferro ferroxidans) used the iron
sulfide as food (an energy source). The bacterium did its thing in water
in contact with the iron mineral. the result is to solubilize the iron as
Iron(II) Sulfate or FeSO4. This solution is run into evaporation ponds,
the green crystals recovered and then roasted to form Spanish red (iron
oxide red).
To keep costs as low as possible, the mine operators in Spain are
happy with a Iron Oxide Red purity that ranges from 83 to 88 percent by
weight. If you as a potter were able to obtain Spanish Red as such bag
after bag, then you'd tweak your recipes to get the best glaze colour.
Sadly, our dealers seem to buy from different sources, and neglect
to tell us the purity level of the new Iron Oxide Red now on sale. Much of
our RIO now comes from automobile scrap that hasn't been digested by
Ferroxidans. And since we are not told what contaminants are included in
this RIO, our glazes misbehave, especially the high RIO crystallines.
Is there a solution to this problem? For most of us, not likely
since we do not want the get into chemical processing. We should ask for
an analysis of the RIO offered to us, and hope it is suitable for our
needs.
til later. Peace. Tom.
Tom Buck ) -- primary address.
"alias" or secondary address.
tel: 905-389-2339 (westend Lake Ontario, province of Ontario, Canada).
mailing address: 373 East 43rd Street, Hamilton ON L8T 3E1 Canada
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