Joyce Lee, Jim Lee on mon 6 jan 97
In recipes for an albany-type slip, can red iron oxide be
substituted for black iron oxide? I ask because my supply house sent
red iron oxide when I had ordered black. I'm not sure whether they just
made a mistake or what? I will call them tomorrow but would like to
know asap because if it is simply a substitution, I can mix my slip
right away. I'm sure some (maybe all) clayarters will know and be
willing to share once again. Thank you.
Joyce
Bright, sunny with a soft blue sky full of billowing white clouds in the
Mojave.
Michael Banks on mon 14 feb 00
Does anyone out there actually know what the black iron oxide sold to
potters as a glaze really is? FeO (ferrous oxide) or Fe3O4 (magnetite)?
Hamer says FeO, but my chemistry book says this that this stuff is a
processed compound (produced by reduction of hematite (Fe2O3) by hydrogen
and turns back into Fe2O3 on gentle heating. So why would we bother paying
a high price for a processed oxide that turns into RIO at the drop of a hat.
I think it is likely that the inexpensive black iron oxide normally sold is
really Fe3O4, which is mined all over the world, does not require further
processing and can be heated to white heat, without turning into anything
else. Oh, BTW magnetite is also the black oxide produced when steel or iron
filings are burned in air or oxygen.
But I don't know that magnetite is the common black iron oxide sold to
potters for sure. And would be grateful if only people who really do know,
could enlighten me (and everyone).
TIA
from
Michael Banks,
New Zealand
mary simmons on tue 15 feb 00
Magnetite is magnetic.......Very low-tech test: throw a magnet into the bag
and see what sticks
Mary
Michael Banks on wed 16 feb 00
Mary Simmons wrote:
> ----------------------------Original message----------------------------
> Magnetite is magnetic.......Very low-tech test: throw a magnet into the
bag
> and see what sticks
>
> Mary
>
Yes, this a definitive test. But I'm not asking for mineralogy lessons.
I'm asking in context of a discussion with a glaze clac software programmer.
He was considering whether the program needed to make adjustments to
reporting FeO instead of Fe2O3 and where to put it in the unity formula box.
It would make a difference to the total mols of iron, if the user started
with FeO or Fe3O4 (which have different percentages of Fe).
I'm requesting if anyone actually knows (without recourse to rushing around
the world with a magnet) -which black oxide is in general use.
I actually never use "black iron oxide" (like most people here, I only use
red iron oxide -Fe2O3, (knowing that FeO is a waste of time). I wish to
know if Frank Hamer was right or not?
Michael Banks,
New Zealand
(Holder of the "Americas" Cup)
David Hewitt on thu 17 feb 00
Mike,
Thought that you might like to see the earlier emails on this subject.
David
I have spoken with Danny Hawkins of Potterycrafts at Stoke-on-Trent. He
assures me that if I order black iron oxide from them it is FeO which is
produced synthetically. He also talked of black iron oxide containing a
lot of Fe3O4, magnetite, and is dark brown. This I presume would a non
synthetic material.
I am also trying to contact Potclays and will post their answer when I
get it.
In message , Michael Banks writes
>----------------------------Original message----------------------------
>Does anyone out there actually know what the black iron oxide sold to
>potters as a glaze really is? FeO (ferrous oxide) or Fe3O4 (magnetite)?
>
>Hamer says FeO, but my chemistry book says this that this stuff is a
>processed compound (produced by reduction of hematite (Fe2O3) by hydrogen
>and turns back into Fe2O3 on gentle heating. So why would we bother paying
>a high price for a processed oxide that turns into RIO at the drop of a hat.
>
>I think it is likely that the inexpensive black iron oxide normally sold is
>really Fe3O4, which is mined all over the world, does not require further
>processing and can be heated to white heat, without turning into anything
>else. Oh, BTW magnetite is also the black oxide produced when steel or iron
>filings are burned in air or oxygen.
>
>But I don't know that magnetite is the common black iron oxide sold to
>potters for sure. And would be grateful if only people who really do know,
>could enlighten me (and everyone).
>
>TIA
>from
>Michael Banks,
>New Zealand
>
--
David Hewitt
David Hewitt Pottery ,
7 Fairfield Road, Caerleon, Newport,
South Wales, NP18 3DQ, UK. Tel:- +44 (0) 1633 420647
FAX:- +44 (0) 870 1617274
Own Web site http://www.dhpot.demon.co.uk
IMC Web site http://digitalfire.com/education/people/hewitt.htm
David Hewitt on thu 17 feb 00
I have now had a chance of talking to John Beeston of Potclays.
His answer is that their black iron oxide is mainly FeO - 75% to 80% and
the rest Fe3O4 magnetite. They obtain it from a German supplier and
described it as a pre-processed material rather than synthetic.
Red iron oxide for pottery suppliers, he said, was all synthetically
produced these days in this country.
--
David Hewitt
David Hewitt Pottery ,
7 Fairfield Road, Caerleon, Newport,
South Wales, NP18 3DQ, UK. Tel:- +44 (0) 1633 420647
FAX:- +44 (0) 870 1617274
Own Web site http://www.dhpot.demon.co.uk
IMC Web site http://digitalfire.com/education/people/hewitt.htm
David Hewitt on thu 17 feb 00
Mike,
Thought you might like to see the earlier emails
Daivd
I have spoken with Danny Hawkins of Potterycrafts at Stoke-on-Trent. He
assures me that if I order black iron oxide from them it is FeO which is
produced synthetically. He also talked of black iron oxide containing a
lot of Fe3O4, magnetite, and is dark brown. This I presume would a non
synthetic material.
I am also trying to contact Potclays and will post their answer when I
get it.
In message , Michael Banks writes
>----------------------------Original message----------------------------
>Does anyone out there actually know what the black iron oxide sold to
>potters as a glaze really is? FeO (ferrous oxide) or Fe3O4 (magnetite)?
>
>Hamer says FeO, but my chemistry book says this that this stuff is a
>processed compound (produced by reduction of hematite (Fe2O3) by hydrogen
>and turns back into Fe2O3 on gentle heating. So why would we bother paying
>a high price for a processed oxide that turns into RIO at the drop of a hat.
>
>I think it is likely that the inexpensive black iron oxide normally sold is
>really Fe3O4, which is mined all over the world, does not require further
>processing and can be heated to white heat, without turning into anything
>else. Oh, BTW magnetite is also the black oxide produced when steel or iron
>filings are burned in air or oxygen.
>
>But I don't know that magnetite is the common black iron oxide sold to
>potters for sure. And would be grateful if only people who really do know,
>could enlighten me (and everyone).
>
>TIA
>from
>Michael Banks,
>New Zealand
>
--
David Hewitt
David Hewitt Pottery ,
7 Fairfield Road, Caerleon, Newport,
South Wales, NP18 3DQ, UK. Tel:- +44 (0) 1633 420647
FAX:- +44 (0) 870 1617274
Own Web site http://www.dhpot.demon.co.uk
IMC Web site http://digitalfire.com/education/people/hewitt.htm
iandol on fri 18 feb 00
------------------
Mary Simmons wrote:
=3E ----------------------------Original message----------------------------
=3E Magnetite is magnetic.......Very low-tech test: throw a magnet into the
bag and see what sticks
=3E Mary
Is this correct? Magnetite is a natural ore of iron which is of itself =
magnetic,
that is, it behaves as a magnet and has magnetic polarity. When suspended to
rotate freely it will align a specimen will align itself with the Earth=92s
magnetic field. So a piece of it which is put into a bag of iron fillings =
will
collect the iron filings.
Surely a better test is to put an unmagnetised soft iron nail into the =
powder
and see if the powder strongly adheres to that.
Ivor. Not intending to pontificate.
mary simmons on sat 19 feb 00
Me neither Ivor (unwilling to pontificate)
BUT, magnetite is weakly magnetic, so it will stick to a magnet, but may
not have enough magnetism to stick to an un-magnetized, yet iron-bearing
mineral. Perhaps the small grain size of a powder would enable the
particles to stick to any iron mineral, though.
Also, whether or not one is willing, it is wise to understand the
mineralogy of magnetite. Not only does it have two valence states of Fe:
(Fe2+, Fe3+)2 O4
, it VERY commonly contains a fair amount of titanium, so the larger ore
bodies of magnetite are likely to be contaminated with considerable Ti.
Magnetite also routinely takes in large amounts of Mn, Mg, Cr, and Al. It
would seem logical that what we buy as black Fe oxide it is NOT magnetite,
for the simple reason that pure magnetite, unadulterated by other oxides,
is relatively rare. Assuming that we can count on any semblance of purity
in the oxides we buy......
Pure black FeO is also rare, so it must be synthesized, if you want a lot
of it.
But if you don't believe your supplier who tells you that it is all FeO,
then the magnet provides a simple and quick way to determine the presence
of magnetite.
Thank you for you always gentlemanly posts, Ivor.
cheers-
Mary
At 11:04 AM 2/18/00 EST, you wrote:
>----------------------------Original message----------------------------
>------------------
>Mary Simmons wrote:
>
>> ----------------------------Original message----------------------------
>
>> Magnetite is magnetic.......Very low-tech test: throw a magnet into the
>
>bag and see what sticks
>
>> Mary
>
>Is this correct? Magnetite is a natural ore of iron which is of itself
magnetic,
>that is, it behaves as a magnet and has magnetic polarity. When suspended to
>rotate freely it will align a specimen will align itself with the Earth s
>magnetic field. So a piece of it which is put into a bag of iron fillings
will
>collect the iron filings.
>
>Surely a better test is to put an unmagnetised soft iron nail into the powder
>and see if the powder strongly adheres to that.
>
>Ivor. Not intending to pontificate.
>
Ron Roy on sat 19 feb 00
Not exactly - there is some difference in colour - and it's better in clays
because it does not stain potters and studios as the red does.
RR
>----------------------------Original message----------------------------
>I actually never use "black iron oxide" (like most people here, I only use
>red iron oxide -Fe2O3, (knowing that FeO is a waste of time). I wish to
>know if Frank Hamer was right or not?
Ron Roy
93 Pegasus Trail
Scarborough
Ontario, Canada
M1G 3N8
Evenings 416-439-2621
Fax 416-438-7849
Michael Banks on sun 20 feb 00
Well, I don't really agree with this (apart from keeping your hands cleaner
Ron). If Potclays black iron oxide is actually 20-25% magnetite (and if
this contains some TiO2), it could add a lot of titanium to a glaze.
Mary Simmons is quite correct about titanium being a common contaminant of
magnetite (though it depends a lot on the source deposit). It can contain
over 10% TiO2 (as exsolved ulvospinel inclusions). This could cause merry
hell in a blue celadon glaze if one were to add a commercial product that
had a few percent of titaniferous magnetite. The red iron oxide in
circulation here down-under, is mercifully free of TiO2 and therefore
potentially safer.
And FeO does turn into red iron oxide anyway at low red heat.
Michael Banks,
Nelson,
New Zealand
> ----------------------------Original message----------------------------
> Not exactly - there is some difference in colour - and it's better in
clays
> because it does not stain potters and studios as the red does.
>
> RR
>
> >----------------------------Original message----------------------------
> >I actually never use "black iron oxide" (like most people here, I only
use
> >red iron oxide -Fe2O3, (knowing that FeO is a waste of time). I wish to
> >know if Frank Hamer was right or not?
David Hewitt on sun 2 jul 00
Because my glaze program, the 'Glaze Workbook', is a spread sheet file
and hence one can see the formula under each cell and hence how any
calculation is being made, a sharp eyed chemist from Holland, Ruud
Ruijgrok pointed out to me that in using black iron oxide in oxidation
my % weight analysis did not take into account the fact that FeO would
in fact take in oxygen and change to 0.5Fe2O3.
Because I made contact with Lawrence Ewing, regarding Matrix and this
question, and his reference of the question to Michael Banks who
suggested that black iron oxide was more likely to be Fe3O4 rather than
FeO, I started making enquiries with suppliers. Some of you may remember
a thread earlier this year on this very point.
With some difficulty I have at last managed to get written
specifications from three UK suppliers. Two supply in the range of 85% -
92% Fe3o4 (Pooterycrafts and Potclays) and the third (W G Ball) 58%
Fe2O3 + 16% Mn2O3. The two which supply Fe3O4 are not quite identical as
can be seen from their physical appearance, one being a finer powder
than the other and the finer one gave a very slightly darker colour in a
glaze test. The third one gave a very different result in the glaze
test.
Prompted by Ruud, each supply was heated to 1000 C and weighed before
and after. The two which were largely Fe3O4 showed a weight increase
reasonably in line with theory. The third showed no increase.
My conclusion from this is that one is most likely to get Fe3O4 when
ordering black iron oxide and so have altered the 'Glaze Workbook' to
include this. My calculations in the 'Glaze Workbook' are now based on
the following:-
FeO in oxidation gives 0.5Fe2O3
Fe3O4 in oxidation gives 1.5Fe2O3
Fe2O3 in oxidation gives Fe2O3
FeO in reduction gives FeO
Fe3O4 in reduction gives 3FeO
Fe2O3 in reduction gives 2FeO
I will shortly be adding an article on this to my web site under Pottery
Techniques and this will include full details of the tests carried out
and photographs of the glaze tests and the before and after heating to
1000 C, the results all being physically quite different. For those that
might be interested I will post Clayart when this is available.
I would appreciate any comments on the above and hearing from others who
may have had experience with changes in their glaze performance
resulting from a change in supply of black iron oxide.
My thanks particularly to Ruud for starting me on this road, also to
Lawrence and Michael for questioning what exactly black iron oxide might
be. My thanks to the three suppliers who went to some trouble to get the
analyses from their suppliers. Lastly to Mike Bailey of Bath Potters'
Supplies for carrying out the heating and weighing tests and hence the
use of his very accurate weighing equipment.
--
David Hewitt
David Hewitt Pottery ,
7 Fairfield Road, Caerleon, Newport,
South Wales, NP18 3DQ, UK. Tel:- +44 (0) 1633 420647
FAX:- +44 (0) 870 1617274
Web site http://www.dhpot.demon.co.uk
Paul Taylor on mon 3 jul 00
Dear David
I also use a spread sheet for my glaze calculations.
Did the analysis of your iron mention any other impurities like titanium.
Regards Paul Taylor
> From: David Hewitt
> Reply-To: Ceramic Arts Discussion List
> Date: Sun, 2 Jul 2000 07:09:06 +0100
> To: CLAYART@LSV.CERAMICS.ORG
> Subject: Black Iron Oxide
>
> Because my glaze program, the 'Glaze Workbook', is a spread sheet file
> and hence one can see the formula under each cell and hence how any
> calculation is being made, a sharp eyed chemist from Holland, Ruud
> Ruijgrok pointed out to me that in using black iron oxide in oxidation
> my % weight analysis did not take into account the fact that FeO would
> in fact take in oxygen and change to 0.5Fe2O3.
> Because I made contact with Lawrence Ewing, regarding Matrix and this
> question, and his reference of the question to Michael Banks who
> suggested that black iron oxide was more likely to be Fe3O4 rather than
> FeO, I started making enquiries with suppliers. Some of you may remember
> a thread earlier this year on this very point.
> With some difficulty I have at last managed to get written
> specifications from three UK suppliers. Two supply in the range of 85% -
> 92% Fe3o4 (Pooterycrafts and Potclays) and the third (W G Ball) 58%
> Fe2O3 + 16% Mn2O3. The two which supply Fe3O4 are not quite identical as
> can be seen from their physical appearance, one being a finer powder
> than the other and the finer one gave a very slightly darker colour in a
> glaze test. The third one gave a very different result in the glaze
> test.
> Prompted by Ruud, each supply was heated to 1000 C and weighed before
> and after. The two which were largely Fe3O4 showed a weight increase
> reasonably in line with theory. The third showed no increase.
> My conclusion from this is that one is most likely to get Fe3O4 when
> ordering black iron oxide and so have altered the 'Glaze Workbook' to
> include this. My calculations in the 'Glaze Workbook' are now based on
> the following:-
> FeO in oxidation gives 0.5Fe2O3
> Fe3O4 in oxidation gives 1.5Fe2O3
> Fe2O3 in oxidation gives Fe2O3
> FeO in reduction gives FeO
> Fe3O4 in reduction gives 3FeO
> Fe2O3 in reduction gives 2FeO
> I will shortly be adding an article on this to my web site under Pottery
> Techniques and this will include full details of the tests carried out
> and photographs of the glaze tests and the before and after heating to
> 1000 C, the results all being physically quite different. For those that
> might be interested I will post Clayart when this is available.
> I would appreciate any comments on the above and hearing from others who
> may have had experience with changes in their glaze performance
> resulting from a change in supply of black iron oxide.
> My thanks particularly to Ruud for starting me on this road, also to
> Lawrence and Michael for questioning what exactly black iron oxide might
> be. My thanks to the three suppliers who went to some trouble to get the
> analyses from their suppliers. Lastly to Mike Bailey of Bath Potters'
> Supplies for carrying out the heating and weighing tests and hence the
> use of his very accurate weighing equipment.
> --
> David Hewitt
> David Hewitt Pottery ,
> 7 Fairfield Road, Caerleon, Newport,
> South Wales, NP18 3DQ, UK. Tel:- +44 (0) 1633 420647
> FAX:- +44 (0) 870 1617274
> Web site http://www.dhpot.demon.co.uk
>
> ______________________________________________________________________________
> 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.
David Hewitt on tue 4 jul 00
In message , Paul Taylor writes
>Dear David
>
> I also use a spread sheet for my glaze calculations.
>Did the analysis of your iron mention any other impurities like titanium.
>
> Regards Paul Taylor
Hello Paul,
Titanium wasn't mentioned, but the W G Ball analysis did include 3-5%
SiO2 + Al2O3 and the Potterycrafts 0.2% Fe(Metallic), 0.1% C, 0.5% SO3
Also, as is normal, all three left a few % unspecified, i.e. they did
not add up to 100%.
David
>
>> From: David Hewitt
>> Reply-To: Ceramic Arts Discussion List
>> Date: Sun, 2 Jul 2000 07:09:06 +0100
>> To: CLAYART@LSV.CERAMICS.ORG
>> Subject: Black Iron Oxide
>>
>> Because my glaze program, the 'Glaze Workbook', is a spread sheet file
>> and hence one can see the formula under each cell and hence how any
>> calculation is being made, a sharp eyed chemist from Holland, Ruud
>> Ruijgrok pointed out to me that in using black iron oxide in oxidation
>> my % weight analysis did not take into account the fact that FeO would
>> in fact take in oxygen and change to 0.5Fe2O3.
>> Because I made contact with Lawrence Ewing, regarding Matrix and this
>> question, and his reference of the question to Michael Banks who
>> suggested that black iron oxide was more likely to be Fe3O4 rather than
>> FeO, I started making enquiries with suppliers. Some of you may remembe=
>r
>> a thread earlier this year on this very point.
>> With some difficulty I have at last managed to get written
>> specifications from three UK suppliers. Two supply in the range of 85% =
>-
>> 92% Fe3o4 (Pooterycrafts and Potclays) and the third (W G Ball) 58%
>> Fe2O3 + 16% Mn2O3. The two which supply Fe3O4 are not quite identical a=
>s
>> can be seen from their physical appearance, one being a finer powder
>> than the other and the finer one gave a very slightly darker colour in =
>a
>> glaze test. The third one gave a very different result in the glaze
>> test.
>> Prompted by Ruud, each supply was heated to 1000 C and weighed before
>> and after. The two which were largely Fe3O4 showed a weight increase
>> reasonably in line with theory. The third showed no increase.
>> My conclusion from this is that one is most likely to get Fe3O4 when
>> ordering black iron oxide and so have altered the 'Glaze Workbook' to
>> include this. My calculations in the 'Glaze Workbook' are now based on
>> the following:-
>> FeO in oxidation gives 0.5Fe2O3
>> Fe3O4 in oxidation gives 1.5Fe2O3
>> Fe2O3 in oxidation gives Fe2O3
>> FeO in reduction gives FeO
>> Fe3O4 in reduction gives 3FeO
>> Fe2O3 in reduction gives 2FeO
>> I will shortly be adding an article on this to my web site under Potter=
>y
>> Techniques and this will include full details of the tests carried out
>> and photographs of the glaze tests and the before and after heating to
>> 1000 C, the results all being physically quite different. For those tha=
>t
>> might be interested I will post Clayart when this is available.
>> I would appreciate any comments on the above and hearing from others wh=
>o
>> may have had experience with changes in their glaze performance
>> resulting from a change in supply of black iron oxide.
>> My thanks particularly to Ruud for starting me on this road, also to
>> Lawrence and Michael for questioning what exactly black iron oxide migh=
>t
>> be. My thanks to the three suppliers who went to some trouble to get th=
>e
>> analyses from their suppliers. Lastly to Mike Bailey of Bath Potters'
>> Supplies for carrying out the heating and weighing tests and hence the
>> use of his very accurate weighing equipment.
>> --
>> David Hewitt
>> David Hewitt Pottery ,
>> 7 Fairfield Road, Caerleon, Newport,
>> South Wales, NP18 3DQ, UK. Tel:- +44 (0) 1633 420647
>> FAX:- +44 (0) 870 1617274
>> Web site http://www.dhpot.demon.co.uk
>>
>> _______________________________________________________________________=
>_______
>> 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.
>
--
David Hewitt
David Hewitt Pottery ,
7 Fairfield Road, Caerleon, Newport,
South Wales, NP18 3DQ, UK. Tel:- +44 (0) 1633 420647
FAX:- +44 (0) 870 1617274
Web site http://www.dhpot.demon.co.uk
John Baymore on tue 4 jul 00
Two supply in the range of 85% - 92% Fe3o4 (Pooterycrafts and Potclays)
and the third (W G Ball) 58% Fe2O3 + 16% Mn2O3. =
David,
Interesting thing here that you point up. Shows that you can't make ANY
assumptions about what you are handling. If I bought a bag of black iron=
oxide I certainly would not expect it to contain 16 percent of
Manganese!!!!!! Whenever I order a new material I always ask for a typic=
al
analysis and an MSDS ......... but I bet there are many people who don't =
do
that.
I am reminded of the time I was trying to find a "lead free" overglaze
enamel. After being told a particular choice were "lead free" by about 3=
heirarchal (sp?) levels of the companies "technical people" I finally
reached one of the ceramic engineering staff ....... and got promptly tol=
d
they DID have lead in them .
Thanks.
Best,
...........................john
John Baymore
River Bend Pottery
22 Riverbend Way
Wilton, NH 03086 USA
603-654-2752 (s)
800-900-1110 (s)
JBaymore@compuserve.com
John.Baymore@GSD-CO.com
"Earth, Water, and Fire Noborigama Woodfiring Workshop August 18-27,
2000"
Sarah House on thu 6 jul 00
Another question about Black Iron Oxide. I have lots, 20+ lbs and no
recipes that call for it. i was told that if i fire it to bisque temp. (04)
it it will reoxidize into red iron oxide, Is this true?
Sarah House
Pat/Kent on fri 7 jul 00
Hi Sarah
Funny you should ask this at this time! Just last night when I was at
class, one of the members raku fired a piece that had two heavy layers of
white crackle with an overlay of a black copper oxide wash brushed on very
thinly. The result was amazing. the result was a semi-gloss copper with no
crackle marks and no problems with the proverbial copper bubbling/ I can.t
wait to try it myself! I was a normal raku process using the white crackle
as a key to temperature. No waiting for the glaze to crackle, just plop
into the post reduction can with shredded paper and sawdust. Can't wait.
Can't wait
Pat Porter
pporter@4dv.net
http://www.geocities.com/iwndy_pines_2000/index.html
Aurora CO 'SA
----- Original Message -----
From: "Sarah House"
To:
Sent: Thursday, July 06, 2000 5:53 AM
Subject: Re: Black Iron Oxide
> Another question about Black Iron Oxide. I have lots, 20+ lbs and no
> recipes that call for it. i was told that if i fire it to bisque temp.
(04)
> it it will reoxidize into red iron oxide, Is this true?
> Sarah House
>
>
____________________________________________________________________________
__
> 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.
Jeff Seefeldt on sun 9 jul 00
can black iron oxide be substituted for RIO in a similar fashion to cobalt carb for
cobalt oxide/?
if so at what rate?
jeff
I've got a class reunion to get finialized before the end of the month, I really
hate it when things that I committed to 5 years ago get in the way of my pottery.
Which do you think I've spent more time on?? Pottery of course!!
David Hewitt on sun 9 jul 00
Sarah,
In theory, yes.
In oxidation FeO gives 0.5Fe2O3
The chances are, however that what you have as black iron oxide is not
FeO but largely, some 85% - 90% Fe3O4 plus a few other oxides. This, in
theory, changes to give 1.5Fe2O3 in oxidation. From my experience,
however, it doesn't look anything like red iron oxide when heated to
1000 C, usually staying black or mauve.
Perhaps you have to hold it at 1000 C for a much longer time than I have
done in order for the full oxidation to take effect.
David
In message , Sarah House writes
>Another question about Black Iron Oxide. I have lots, 20+ lbs and no
>recipes that call for it. i was told that if i fire it to bisque temp. (0=
>4)
>it it will reoxidize into red iron oxide, Is this true?
>Sarah House
>
--
David Hewitt
David Hewitt Pottery ,
7 Fairfield Road, Caerleon, Newport,
South Wales, NP18 3DQ, UK. Tel:- +44 (0) 1633 420647
FAX:- +44 (0) 870 1617274
Web site http://www.dhpot.demon.co.uk
Martin Howard on sun 9 jul 00
I've just done some tests using my base glaze and then adding percentages of
Red Iron Oxide and some of Black Iron Oxide.
They turned out very similar.
However the Black Iron Oxide sample tiles were a little spotty, but
interestingly so.
So, from what I have read on this thread, it would appear that my Black Iron
Oxide has a percentage of Manganese, or something else.
Martin Howard
Webb's Cottage Pottery
Woolpits Road, Great Saling
BRAINTREE, Essex CM7 5DZ
England
martin@webbscottage.co.uk
David Hewitt on thu 13 jul 00
Jeff,
Yes. Assuming you are working in oxidation. Assuming the black iron
oxide is Fe3O4 and the red Fe2O3 then
Fe3O4 in oxidation gives 3/2 Fe2O3
David
In message , Jeff Seefeldt writes
>can black iron oxide be substituted for RIO in a similar fashion to cobal=
>t carb for
>cobalt oxide/?
>
>if so at what rate?
>
>
>jeff
>
>I've got a class reunion to get finialized before the end of the month, I=
> really
>hate it when things that I committed to 5 years ago get in the way of my=
> pottery.
>Which do you think I've spent more time on?? Pottery of course!!
>
--
David Hewitt
David Hewitt Pottery ,
7 Fairfield Road, Caerleon, Newport,
South Wales, NP18 3DQ, UK. Tel:- +44 (0) 1633 420647
FAX:- +44 (0) 870 1617274
Web site http://www.dhpot.demon.co.uk
David Hewitt on sun 23 jul 00
A few weeks ago I sent in a piece about my findings on the different
forms of Black Iron Oxide that I had come across and how this had caused
me to change my glaze calculation program, the Glaze Workbook.
I said at that time that I would be amplifying on this by adding a page
to my web site and would let Clayart know when this was available. This
is now available under 'Pottery Techniques'/ 'What is Black Iron Oxide?'
it includes the suppliers analysis data, results of heating the
different materials to 1000 C in oxidation, weights before and after
together with photographs. Also results of a glaze test using each of
the materials in question.
--
David Hewitt
David Hewitt Pottery ,
7 Fairfield Road, Caerleon, Newport,
South Wales, NP18 3DQ, UK. Tel:- +44 (0) 1633 420647
FAX:- +44 (0) 870 1617274
Web site http://www.dhpot.demon.co.uk
Mitsuru Cope on tue 2 apr 02
Hello Clayarters,
A student asked me what is the difference between red iron oxide and black
iron oxide.
He is going to do sawdust firing and planing to apply red iron oxide in slip
to get a real black. Someone mentioned about black iron oxide. I never used
black iron and I don't know anything about it, so I told him that I would
ask Clayarters. I hope someone can help me.
Mitsuru Cope
Snail Scott on tue 2 apr 02
At 12:34 PM 4/2/02 -0500, you wrote:
>A student asked me what is the difference between red iron oxide and black
>iron oxide.
Basically, it's two different combinations of iron with oxygen.
When you fire, you mess with the oxygen atoms in the molecule,
and they end up turning into the same type of iron oxide no matter
which sort you started with. With a very low firing, there might
be some visible difference remaining afterward, but at most
firing temperatures, you won't notice much difference at all.
-Snail
Ababi on wed 3 apr 02
Hello Mitsuru Cope.
There is a chemical different, I do not want to go into the
explanation, I leave it to these that can explain better.
It is black but becomes brown.
more brown then red.
I suggest you to add it to a glaze that has in the recipe red iron
oxide to see the different.
Here from Marty Anderson, was sent some years ago
MARTY SANDY BROWN
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Cone 6 1222 deg.C. -
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
G-200 Potash Feldspar 31.00
SILICA 24.00
Calcium Carbonate 24.00
EPK Kaolin 12.00
ZINC OXIDE 8.00
Bentonite 2.00
Rutile 3.20
Red Iron Oxide 3.20
Black Iron Oxide 3.00
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Seger Weight%
KNO 0.134 4.86%
CaO 0.612 14.75%
MgO 0.003 0.06%
ZnO 0.250 8.75%
Al2O3 0.265 11.60%
SiO2 2.186 56.44%
TiO2 0.103 3.54%
K2O 0.093 3.76%
Na2O 0.041 1.09%
Al:Si 8.25
Expan. 7.87
ST 382.36
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Clay Body white or buff
Colour light brown
Glaze Type semmy matte,
Opacity almost
Texture sandy
Stability yes
Fit yes
Last changed: today back to to American materials
Status static
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Comment: Lately I like it less, I think I would like it with 2 black
iron and 4 red iron.
Yet a lovely glaze.
Ababi Sharon
Kibbutz Shoval- Israel
Glaze addict
ababisha@shoval.org.il
http://members4.clubphoto.com/ababi306910/
http://www.milkywayceramics.com/cgallery/asharon.htm
http://www.israelceramics.org/
---------- Original Message ----------
>Hello Clayarters,
>A student asked me what is the difference between red iron oxide and
>black
>iron oxide.
>He is going to do sawdust firing and planing to apply red iron oxide in
>slip
>to get a real black. Someone mentioned about black iron oxide. I never
>used
>black iron and I don't know anything about it, so I told him that I
>would
>ask Clayarters. I hope someone can help me.
>Mitsuru Cope
>________________________________________________________________________
>______
>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.
David Hewitt on wed 3 apr 02
It is a good question. I would ask for an analysis from your supplier as
it can vary a lot.
I did some work on this a little while back and you see the results on
my web site under Pottery Techniques / Raw Materials - Do you know what
you are Buying? You will see that the glaze results varied quite a bit
according which type of black iron oxide you get.
Hope this helps you.
http://www.dhpot.demon.co.uk
David
In message , Mitsuru Cope writes
>Hello Clayarters,
>
>A student asked me what is the difference between red iron oxide and blac=
>k
>iron oxide.
>He is going to do sawdust firing and planing to apply red iron oxide in s=
>lip
>to get a real black. Someone mentioned about black iron oxide. I never us=
>ed
>black iron and I don't know anything about it, so I told him that I would
>ask Clayarters. I hope someone can help me.
>
>Mitsuru Cope
--
David Hewitt
David Hewitt Pottery ,
7 Fairfield Road, Caerleon, Newport,
South Wales, NP18 3DQ, UK. Tel:- +44 (0) 1633 420647
FAX:- +44 (0) 870 1617274
Web site http://www.dhpot.demon.co.uk
Ababi on thu 4 apr 02
I remember David you have written once that in some tests you found
Manganese dioxide in the black iron oxide. I don't talk safety now but
variation.
I want to add here a result of test, I have made; I added to white
stoneware 5 or ten, more likely 5% black iron oxide and got kind of
purple brown claybody.
To this base, was going in my school, for raku, I added in some tests
2-5% black iron oxide and got kind of eggplant,
Here is the base, I cannot convert the materials.
SAPIR RAKU BASE
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Cone 0 945 deg.C. -
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Seger Weight%
KNO 0.649 22.69%
CaO 0.341 8.66%
MgO 0.010 0.19%
Al2O3 0.124 5.71%
B2O3 0.680 21.43%
SiO2 1.514 41.24%
TiO2 0.002 0.08%
K2O 0.305 13.03%
Na2O 0.344 9.67%
Al:Si 12.25
Expan. 11.98
ST 249.06
Ababi Sharon
Kibbutz Shoval- Israel
Glaze addict
ababisha@shoval.org.il
http://members4.clubphoto.com/ababi306910/
http://www.milkywayceramics.com/cgallery/asharon.htm
http://www.israelceramics.org/
---------- Original Message ----------
>It is a good question. I would ask for an analysis from your supplier as
>it can vary a lot.
>I did some work on this a little while back and you see the results on
>my web site under Pottery Techniques / Raw Materials - Do you know what
>you are Buying? You will see that the glaze results varied quite a bit
>according which type of black iron oxide you get.
>Hope this helps you.
>http://www.dhpot.demon.co.uk
>David
>In message , Mitsuru Cope writes
>>Hello Clayarters,
>>
>>A student asked me what is the difference between red iron oxide and
>blac=
>>k
>>iron oxide.
>>He is going to do sawdust firing and planing to apply red iron oxide
>in s=
>>lip
>>to get a real black. Someone mentioned about black iron oxide. I never
>us=
>>ed
>>black iron and I don't know anything about it, so I told him that I
>would
>>ask Clayarters. I hope someone can help me.
>>
>>Mitsuru Cope
>--
>David Hewitt
>David Hewitt Pottery ,
>7 Fairfield Road, Caerleon, Newport,
>South Wales, NP18 3DQ, UK. Tel:- +44 (0) 1633 420647
>FAX:- +44 (0) 870 1617274
>Web site http://www.dhpot.demon.co.uk
>________________________________________________________________________
>______
>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.
Paul on mon 12 aug 02
Does anyone know if black iron oxide can be used in place of red iron oxide?
Or is there some ratio that can be applied when substituting? A friend of
mine got a whole bucket of it for free somehow and we are trying to figure
out how to use it. thanks.
Paul Borian
David Hewitt on tue 13 aug 02
Paul
If you know the composition of your black iron oxide, then I am sure you
can substitute it for red iron oxide.
From my own experience black iron oxide can be very variable and may in
fact be largely Fe3O4.
If you care to visit my web site and go to Pottery Techniques / Raw
Materials - Do you know what you are buying? You will see what I came
across with different composition black iron oxides.
http://www.dhpot.demon.co.uk
David
In message , Paul writes
>Does anyone know if black iron oxide can be used in place of red iron oxide?
>Or is there some ratio that can be applied when substituting? A friend of
>mine got a whole bucket of it for free somehow and we are trying to figure
>out how to use it. thanks.
>Paul Borian
--
David Hewitt
David Hewitt Pottery ,
7 Fairfield Road, Caerleon, Newport,
South Wales, NP18 3DQ, UK. Tel:- +44 (0) 1633 420647
FAX:- +44 (0) 870 1617274
Web site http://www.dhpot.demon.co.uk
Mark Potter on tue 13 aug 02
I'd really appreciate some additional input on this topic. An excellent
question.
From what I can tell the many hues of iron glazes are due in part to the
many different oxides that Iron can form, FeO2, Fe2O3, Fe3O4, Fe4O5 and
so forth.
Depending on the amount of reduction in the atmosphere, all, none, or
part of the oxide composition in the glaze looses oxygen and changes
first to another oxide before changing to metallic iron (extreme
reduction).
I'd love to be corrected on this and to learn more about what oxide
formula red and black iron oxide are (supposed to be).
-----Original Message-----
From: Ceramic Arts Discussion List [mailto:CLAYART@LSV.CERAMICS.ORG] On
Behalf Of David Hewitt
Sent: Tuesday, August 13, 2002 3:00 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: BLACK IRON OXIDE
Paul
If you know the composition of your black iron oxide, then I am sure you
can substitute it for red iron oxide.
From my own experience black iron oxide can be very variable and may in
fact be largely Fe3O4.
If you care to visit my web site and go to Pottery Techniques / Raw
Materials - Do you know what you are buying? You will see what I came
across with different composition black iron oxides.
http://www.dhpot.demon.co.uk
David
In message , Paul writes
>Does anyone know if black iron oxide can be used in place of red iron
oxide?
>Or is there some ratio that can be applied when substituting? A friend
of
>mine got a whole bucket of it for free somehow and we are trying to
figure
>out how to use it. thanks.
>Paul Borian
--
David Hewitt
David Hewitt Pottery ,
7 Fairfield Road, Caerleon, Newport,
South Wales, NP18 3DQ, UK. Tel:- +44 (0) 1633 420647
FAX:- +44 (0) 870 1617274
Web site http://www.dhpot.demon.co.uk
________________________________________________________________________
______
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.
Ababi on fri 16 aug 02
Hello David.
Thank you for the article about the black iron oxide.
If i understood you correctly, by weighing the material the way you describe in you
site i can learn if I have pure black iron oxide or black iron oxide with manganese?
I use black iron oxide in claybodies, up to 5%. How much manganese might be in the
mix. Is it a mix or is it kind of truck element?
Ababi
---------- Original Message ----------
>Paul
>If you know the composition of your black iron oxide, then I am sure you
>can substitute it for red iron oxide.
>From my own experience black iron oxide can be very variable and may in
>fact be largely Fe3O4.
>If you care to visit my web site and go to Pottery Techniques / Raw
>Materials - Do you know what you are buying? You will see what I came
>across with different composition black iron oxides.
>http://www.dhpot.demon.co.uk
>David
>In message , Paul writes
>>Does anyone know if black iron oxide can be used in place of red iron oxide?
>>Or is there some ratio that can be applied when substituting? A friend of
>>mine got a whole bucket of it for free somehow and we are trying to figure
>>out how to use it. thanks.
>>Paul Borian
>--
>David Hewitt
>David Hewitt Pottery ,
>7 Fairfield Road, Caerleon, Newport,
>South Wales, NP18 3DQ, UK. Tel:- +44 (0) 1633 420647
>FAX:- +44 (0) 870 1617274
>Web site http://www.dhpot.demon.co.uk
>______________________________________________________________________________
>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.
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