Snail Scott on tue 6 mar 01
>...very beautiful sculpture with a purple-ish
>finish. The caption said it was crocus martis...
I've never seen much difference between the
colors of iron oxide after firing, even at
very low temperatures.
Are you sure it was a fired surface, and
not just using the crocus martis as a raw
pigment, (in the manner that iron compounds
are used with binders to make paint,) or
as a simple, rubbed surface? I often use
unfired pigments and materials with binders
on my sculpture (after firing).
Snail
Charlie Cummings on tue 6 mar 01
Bill,
Last year I was looking for a source of soluble iron for an anemic
shino. I did some investigation into the nature of crocus martis. From
the Internet I found that the name in the alchemical sense referred to a
purple soluble iron compound. Other sources refer to it as an archaic term
for Fe2O3.
Friends who have used crocus martis said that it sometimes does unexpected
things in glazes.
Ceramic reference books, like Hopper, Hamer, and Fournier, give differing
accounts for this material. Interesting reading though.
The material I received from my supplier looks for all the world like
regular red iron oxide. I have to assume that I got the calcined or partly
calcined version (see Hamer.) When brushed on clay or a glaze and fired to
cone 10 the results were the same as Fe2O3.
Crocus Martis did great things for my shino, but I don't think it is
soluble. If you find a source for the purple crocus martis (might be
anhydrous iron sulfate?) please let me know.
Charlie Cummings
www.claylink.com
Wade Blocker on tue 6 mar 01
Bill,
Crocus martis is natural purple red oxide of iron, ferric oxide,Fe2 O3.It
may give darker browns than red iron oxide. Mia in ABQ
Bill Hanke on tue 6 mar 01
I saw a picture the other day of a very beautiful sculpture with a
purple-ish finish. The caption said it was crocus martis, which I had never
heard of. Sooo I started looking in the archives and found a recipe for
purple terra sigillata which used crocus martis, and several questions about
what it was. Sooo I kept looking and, depending where I went on the net, it
was described as purple iron oxide, same as Spanish iron oxide, same as
black iron oxide but less concentrated, FeO3,Fe2O3,then I found a comment
that all iron oxide is converted to Fe2O3 when fired anyway.
What's going on?
Has anyone ever used this stuff?
Know what it really is?
Made a purple terra sig?
Like purple?
Read Harold and the Purple Crayon?
Much Aloha,
Bill Hanke
Maui,Hi.
Khaimraj Seepersad on wed 7 mar 01
Hello to All ,
Bill Hanke ,
in Fine Art we call purple iron oxide - Mars Violet or Caput
Mortuum .
We have a few deposits of this clay type and it will fire to
cone 6 as a deep rich purple .
Normally , I add a little white clay to lighten the colour , so
you can see it is purple . Otherwise you have to use
sunlight to see the purple.
Also makes a purple Terra Sigillata .
By the way you can just buy Mars Violet at a Fine Art pigment
supplier , like Kremer or Sinopia on-line.
Once again all I can suggest is to test . Mars Violet is not an
expensive pigment - 1lb for about $15.00 US plus shipping .
Hope this helps ,
Khaimraj
* If Mars Black [ Blue type ] can resist the firing , with a white
clay may make a beautiful grey blue .
-----Original Message-----
From: Bill Hanke
To: CLAYART@LSV.CERAMICS.ORG
Date: 06 March 2001 19:14
Subject: purple iron oxide/crocus martis
>I saw a picture the other day of a very beautiful sculpture with a
>purple-ish finish. The caption said it was crocus martis, which I had never
>heard of. Sooo I started looking in the archives and found a recipe for
>purple terra sigillata which used crocus martis, and several questions
about
>what it was. Sooo I kept looking and, depending where I went on the net, it
>was described as purple iron oxide, same as Spanish iron oxide, same as
>black iron oxide but less concentrated, FeO3,Fe2O3,then I found a comment
>that all iron oxide is converted to Fe2O3 when fired anyway.
>What's going on?
>Has anyone ever used this stuff?
>Know what it really is?
>Made a purple terra sig?
>Like purple?
>Read Harold and the Purple Crayon?
>
>Much Aloha,
>Bill Hanke
>Maui,Hi.
ferenc jakab on wed 7 mar 01
Bill,
Hamer and Hamer, describe Crocus Martis as "Anhydrous iron sulfate
.....FeSo4. A cheap iron salt..... Givingsoft yellows in lead glazes and
greenish colours in boron glazes, (3%-6%)." Page 93 in the 1999 reprint. it
goes on to say that calcining at 900 deg C gives it a dark purple brown
colour.
Feri.
Pam on wed 7 mar 01
Yes, I've used it, and my completely subjective observation is that it has a
"rosier" tone than iron oxide. It's like a reddish brown with an alizaron
crimson "note," if you will. There was a discussion about this maybe years
ago and there were a number of informed posts from some of the gurus, as I
think I recall. That's probably the discussion that you refer to. I think
that it's iron oxide that has other naturally occurring stuff in it.
I've used the crocus martis in slip. Then after the bisque, wax out areas
and apply black glaze over it and that lovely deep reddish-purple peeks
through. With clear glaze over it, it turns a greenish gold. This is
firing on white stoneware around cone 6-8 (it's a classroom situation and I
don't do the firing).
Pam
in Virginia
> I saw a picture the other day of a very beautiful sculpture with a
> purple-ish finish. The caption said it was crocus martis, which I had
never
> heard of. Sooo I started looking in the archives and found a recipe for
> purple terra sigillata which used crocus martis, and several questions
about
> what it was. Sooo I kept looking and, depending where I went on the net,
it
> was described as purple iron oxide, same as Spanish iron oxide, same as
> black iron oxide but less concentrated, FeO3,Fe2O3,then I found a comment
> that all iron oxide is converted to Fe2O3 when fired anyway.
> What's going on?
> Has anyone ever used this stuff?
> Know what it really is?
> Made a purple terra sig?
> Like purple?
> Read Harold and the Purple Crayon?
>
> Much Aloha,
Ababi on wed 7 mar 01
In my site http://members4.clubphoto.com/ababi306910/RAKU_WARE/
Slide 11 there is concentrated Iron sulfate liquid, poured over a raku
plate. not typical. I would say, at list about raku, that if you spray it
over a piece you may get a similar color to your T pot at your site.
Richard Zakin writes too that this is the crocus martis And I tell you that
it is a poisonous material.
Ababi Sharon
ababisha@shoval.ardom.co.il
http://members4.clubphoto.com/ababi306910/
----- Original Message -----
From: "Charlie Cummings"
To:
Sent: Wednesday, March 07, 2001 5:22 AM
Subject: Re: purple iron oxide/crocus martis
> Bill,
>
> Last year I was looking for a source of soluble iron for an anemic
> shino. I did some investigation into the nature of crocus martis. From
> the Internet I found that the name in the alchemical sense referred to a
> purple soluble iron compound. Other sources refer to it as an archaic
term
> for Fe2O3.
>
> Friends who have used crocus martis said that it sometimes does unexpected
> things in glazes.
>
> Ceramic reference books, like Hopper, Hamer, and Fournier, give differing
> accounts for this material. Interesting reading though.
>
> The material I received from my supplier looks for all the world like
> regular red iron oxide. I have to assume that I got the calcined or
partly
> calcined version (see Hamer.) When brushed on clay or a glaze and fired
to
> cone 10 the results were the same as Fe2O3.
>
> Crocus Martis did great things for my shino, but I don't think it is
> soluble. If you find a source for the purple crocus martis (might be
> anhydrous iron sulfate?) please let me know.
>
> Charlie Cummings
> www.claylink.com
>
>
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