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clayart - thread 'red iron oxide'

Sep. 23, 2024

clayart - thread 'red iron oxide'

Dr.Tom Roess on wed 2 aug 00

Hi everyone,
I have a quick question regarding Red iron oxide. We were recent=
ly
given a nice quantity of the stuff but it was just labeled "red iron
oxide". Does this mean it is 100% unless labeled 50%? Also, since most =
of
our recipes have been based on using 50%, can we just use half as much an=
d
get approximately the same results?
I hope as many of you as possible will answer. I have noticed
that when it is a matter of opinion, there will be many postings , but wh=
en
it''s a straightforward question, not too many people take the time to he=
lp
out. I wonder why this is. =

Regards, Lou in Snowmass. =

Dennis E. Tobin on thu 3 aug 00

Lou
Firswt say hi to Doug at the Ranch. He is an old friend from Mo. We
started in clay at the same time, and back in 94 I was fortunate enough to
have a 2 month residence at the Ranch.

Regarding the iron. I have never heard of a substance "50% iron". What was
the other 50%. My supplier sells a light iron oxide and a dark iron oxide,
maybe similar. Test the new stuff.
Good luck
Dennis Tobin

>Hi everyone,
> I have a quick question regarding Red iron oxide. We were recently
>given a nice quantity of the stuff but it was just labeled "red iron
>oxide". Does this mean it is 100% unless labeled 50%? Also, since most of
>our recipes have been based on using 50%, can we just use half as much and
>get approximately the same results?
> I hope as many of you as possible will answer. I have noticed
>that when it is a matter of opinion, there will be many postings , but when
>it''s a straightforward question, not too many people take the time to help
>out. I wonder why this is.
>Regards, Lou in Snowmass.
>______________________________________________________________________________
>Send postings to
>
>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
>.

Dennis Tobin
Associate Professor
Art Department
Miami University
Oxford, Ohio
(513) 529-

Craig Martell on thu 3 aug 00

Lou wanted to know:
>We were recently given a nice quantity of the stuff but it was just
>labeled "red iron oxide". Does this mean it is 100% unless labeled
>50%? Also, since most of our recipes have been based on using 50%, can we
>just use half as much and get approximately the same results?

Hi:

If the stuff is in the original bag from the processor, look for the
company name and possibly some numbers to identify the stuff. If this is
the case, you can contact the company that processed the iron and ask what
the strength is.

The only way to determine the percentage you'll be using is to do some
tests. The number of tests you do and how you set the incremental amounts
is a matter of choice and common sense and I'll leave that up to
you. Here's a quick opinion though. Start with your original percentages
and see how it looks.

> I have noticed that when it is a matter of opinion, there will be many
> postings , but when
>it''s a straightforward question, not too many people take the time to help
>out. I wonder why this is.

I have a feeling that you're going to find out! :>)

later, Craig Martell in Oregon

Shelley Corwin on thu 3 aug 00

lou-call anderson ranch, they must know. s

Ron Roy on thu 3 aug 00

Hi Lou,

Simple answer - you don't know whats in the bag so you do a line blend in a
glaze and find out how strong it is - Start at 100% and work down to 40% -
10% at a time.

As to your second question - I have noticed this as well. I'm sure it has
to do with the level technical awarness - it's not easy to wade through all
those opinions to get to the "straightforward" ones. Never mind - we will
work it out.

Perhaps - if you think it's a question I or some one else on the list can
answer - put our initals in the subject line - that will get our attention.

RR

>Hi everyone,
> I have a quick question regarding Red iron oxide. We were recently
>given a nice quantity of the stuff but it was just labeled "red iron
>oxide". Does this mean it is 100% unless labeled 50%? Also, since most of
>our recipes have been based on using 50%, can we just use half as much and
>get approximately the same results?
> I hope as many of you as possible will answer. I have noticed
>that when it is a matter of opinion, there will be many postings , but when
>it''s a straightforward question, not too many people take the time to help
>out. I wonder why this is.
>Regards, Lou in Snowmass.

Ron Roy
93 Pegasus Trail
Scarborough
Ontario, Canada
M1G 3N8
Evenings 416-439-
Fax 416-438-

on thu 3 aug 00

Can someone tell me the difference in the red iron oxide i use every day and
"Spanish Red Iron Oxide"... Is one redder than the other.....or what?
Thanks Jim in Dallas where it has cooled down to 103 degrees.....

Paul Lewing on thu 3 aug 00

Lou,
There's no way to tell what may be in that bag without testing it.
There is a huge variety of brands and strengths of iron oxide out there,
processed in several different ways, with varying amounts of many
different contaminants. The first thing to do is fire a test uzing the
same amount you're used to, and adust from there. You probably won't
have to adjust much one way or the other to get the same intensity of
color, but if there are significant amounts of stuff other than iron in
there, in either the old or the new stuff, the shade may vary. The most
common contaminant is probably manganese, which would make it duller and
browner. As a general rule, not hard and fast though, the purer the
iron is, the redder it will be in its raw state.
As to your other question, I think many people are reluctant to answer
factual questions because they are afraid of not being right, whereas
they know that opinions are neither wrong nor right, they are just what
they believe. I think, too, that most people on this list know a whole
lot more than they give themselves credit for. But they wait for those
people who have answered the factual qestions before to do it again.
Paul Lewing, Seattle,
who always sounds like he knows what he's talking about whether that's
the case or not.

iandol on fri 4 aug 00

Dear Dr Tom,

Opinions are easy to express. Hard facts take time to suss out, which =
means you have to make an effort to think about what you are searching. =
At least, that is my opinion.

Now for your iron oxide. Unless you are being conned by a flimflam man =
who is putting water in your beer it should be all red iron oxide, =
Fe2O3. But since things are seldom perfect there may be other iron =
minerals in the stuff but not in amounts which you would notice. Also, =
if it is raw mined and not manufactured, it may be contaminated with =
clay or other common things like fine sand.

Now when would you need fifty percent as a value in a glaze recipe? And =
if your label says fifty percent, what is the other fifty percent in the =
bag?

Hope that helps,

Ivor Lewis

Tom Buck on fri 4 aug 00

Jim:
The archives have data on the various red iron oxides, but during
the last go-around it was firmly stated that Spanish red iron oxide has a
Fe2O3 content of 87% (more or less), and tends to have smaller particles
than do the synthetic varieties. And it seems most syn RIO varieties have
a broader range in particle sizes, a purity of 90-95% Fe2O3.
Spain has a huge natural deposit of low-grade Fe2O3 that is
processed to high-grade; the upgrading doesn't remove all the clayey
materials that are included in the mineral ore.
The syn RIOs are usually made from scrap steel, so there would be
some small amounts of other metals (usually ignored) in the syn RIO
potters receive.
til later. Peace. Tom B.

Tom Buck ) : 905-389-
(westend Lake Ontario, province of Ontario, Canada).
mailing address: 373 East 43rd Street,
Hamilton ON L8T 3E1 Canada

Dr.Tom Roess on sat 5 aug 00

Thanks to Craig, Tom, Ivor, Ron, Paul and Dennis, who answered my inquiry=
=

about Red Iron Oxide. (Seems to be our core group ) And Dennis, I will s=
ee =

Doug next week and pass along your greetings.
I may have mislead some readers in talking about 50% RIO. I did=
n't =

mean a recipe called for 59% of the recipe to be Red Iron Oxide. When I =
first
started working at our studio, we had two containers of red iron oxide, o=
ne =

labeled 50%, the other labeled 100%. I was told to use the 50% unless the=
=

recipe specifically called for 100% or "pure" red iron oxide. It never =

occurred to me to ask what the other 50% was in the container. =

The consensus is to test the new product and see what it does.
Thanks again, guys,
Lou in Snowmass=

Dapogny.Gail on mon 11 aug 03

Earlier this summer, I was remixing a glaze (orange) and was stopped dead
in my tracks by the color of our (guild) iron oxide. It was sort of rosy,
muted. I felt sure that it was not what I remembered. With trepidation, I
went on mixing and then glazed --- had an art fair just ahead.

I wasn't surprised when the glaze came out different --- not orange as it
had always been, but more of a gold. Acceptable, not ugly, but not what I
wanted.

Later I went to our archives and read old posts on iron. Interesting but a
little confusing. Basically the old posts suggested that the better the
raw color of the iron, the purer and brighter the color will be. On the
subject of Spanish Fe, the posts were mixed.

So --question: did that pinkish iron indicate a less pure strain? Should
I buy myself something redder? If so, can you all suggest particular iron
oxides and reliable sources?

Appreciate any forthcoming help.

Thanks------Gail

Gail Dapogny
Ann Arbor, Michigan

http://www.silverhawk.com/ex99/dapogny (single historical photo - no longer
registered with Silverhawk)

Smith, Judy on thu 18 oct 07

I am having a problem with red iron oxide. I mix it with a little water
and paint it on my bisque ware. Then I rub off the excess. When is it
dry, I cover it with 3 coats of clear Coyote glaze and fire to cone 6.
The problem is that when I remove the pots from the kiln, the iron oxide
does not show under the clear glaze. What am I doing wrong? Should I
skip the rubbing off the excess step?

=20

Thanks,=20

Judy Smith

Maggie Jones on thu 18 oct 07

Red Iron Oxide is very strong in the raw state, meaning it stains hands
and clothes etc but can be weak in the firing.
Sounds like you are taking too much off or using too much water. There
needs to be a definite layering of particles to show up through any
glaze.

Cobalt...on the other hand, esp. oxide, is the opposite, very strong in
the firing , will show up where you never saw it on your piece.

Maggie

http://TurtleIslandPottery.com
Maggie and Freeman Jones

.........next OPEN Oct 27th Bring a friend!

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

On Thu, 18 Oct 10:10:25 - "Smith, Judy"
writes:
> I am having a problem with red iron oxide. I mix it with a little
> water
> and paint it on my bisque ware. Then I rub off the excess. When is
> it
> dry, I cover it with 3 coats of clear Coyote glaze and fire to cone
> 6.
> The problem is that when I remove the pots from the kiln, the iron
> oxide
> does not show under the clear glaze. What am I doing wrong? Should
> I
> skip the rubbing off the excess step?
>
>
>
> Thanks,
>
> Judy Smith
>
>
_________________________________________________________________________
_____
> Clayart members may send postings to:
>
> You may look at the archives for the list, post messages, or change
> your
> subscription settings here: http://www.acers.org/cic/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
>
>
>

Fredrick Paget on thu 18 oct 07

>I am having a problem with red iron oxide. I mix it with a little water
>and paint it on my bisque ware. Then I rub off the excess. When is it
>dry, I cover it with 3 coats of clear Coyote glaze and fire to cone 6.
>The problem is that when I remove the pots from the kiln, the iron oxide
>does not show under the clear glaze. What am I doing wrong? Should I
>skip the rubbing off the excess step?
>
>Judy Smith

This sounds like the same problem we ran into with iron toner laser
decals. The glaze is bleaching out the red iron oxide to an almost
colorless yellow.
I never found a clear glaze that would not do that.
Maybe you could use a mason stain instead of iron oxide and find it
would not bleach.
Fred Paget
--
Twin Dragon Studio
Mill Valley, CA, USA

Back from China with lots of new ideas. Saw parts of China I had
never been to before.

Gayle Bair on thu 18 oct 07

My solution is to use a very thin application of clear glaze.
I make a oxide rich slip with red and black oxide, burnt umber and
a bit of black mason stain.
It only fades slightly when under a thick application of glaze.
Note I do not customarily wipe it off but sgraffito through the slip so it
is not
thinned by wiping. However I have made pieces with just RIO wiped off and it
doesn't
fade with a thinned clear glaze. By thin I mean skim milk .... very watery!

Gayle Bair
Bainbridge Island, WA
Tucson, AZ
http://claybair.com

-----Original Message-----
From: Fredrick Paget

>I am having a problem with red iron oxide. I mix it with a little water
>and paint it on my bisque ware. Then I rub off the excess. When is it
>dry, I cover it with 3 coats of clear Coyote glaze and fire to cone 6.
>The problem is that when I remove the pots from the kiln, the iron oxide
>does not show under the clear glaze. What am I doing wrong? Should I
>skip the rubbing off the excess step?
>
>Judy Smith

This sounds like the same problem we ran into with iron toner laser
decals. The glaze is bleaching out the red iron oxide to an almost
colorless yellow.
I never found a clear glaze that would not do that.
Maybe you could use a mason stain instead of iron oxide and find it
would not bleach.
Fred Paget
--
Twin Dragon Studio
Mill Valley, CA, USA

Back from China with lots of new ideas. Saw parts of China I had
never been to before.

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John Sankey on fri 19 oct 07

"I am having a problem with red iron oxide. I mix it with a little water
and paint it on my bisque ware. Then I rub off the excess. When is it
dry, I cover it with 3 coats of clear Coyote glaze and fire to cone 6.
The problem is that when I remove the pots from the kiln, the iron oxide
does not show under the clear glaze. What am I doing wrong? Should I
skip the rubbing off the excess step?"

This is just a guess, but I suspect that your red iron oxide
Fe2O3 is being converted to FeO during firing and is a light
transparent yellow when it then combines with the silica in your
clear glaze. My results with iron glazes suggest that to get a
red from iron, it has to be on the outside surface.
http://sankey.ws/glazeiron.html

--
Include 'Byrd' in the subject line of your reply
to get through my spam filter.

May Luk on sat 20 oct 07

Hello Judy;

Why don't you try painting the iron oxide as 'on glaze' as per Maiolica. Glaze first, then paint your design with iron oxided water. It might drag a bit but try different type of brush. I have done Chinese calligraphy - running script - like that. No fading problem.

I am sure you are aware that if there's too much coloring oxide, it's not 'food safe'

Regards
May
Kings County
My new kiln is working. Wahay!!

Snail Scott on mon 22 oct 07

Date: Thu, 18 Oct 10:10:25 -
From: "Smith, Judy"
Subject: red iron oxide

>...red iron oxide. I mix it with a little water
and paint it on my bisque ware. Then I rub off the excess. When is it
dry, I cover it with 3 coats of clear Coyote glaze and fire to cone 6.
The problem is that when I remove the pots from the kiln, the iron oxide
does not show under the clear glaze....

Most clear glazes will 'fade' the color of an iron
oxide wash. Consider using an engobe (or commercial
'underglaze') of similar color if you want the
'just-rubbed' look to endure unchanged. Also, a
combo of several similar-colored engobes can give a
slightly varied effect which is less 'flat' and
somewhat richer than just one color alone.

Why are you glazing it anyway? Do you need to for
some functional reason?

Personally, I prefer bare clay with any oxide wash;
the combination of shininess and 'antiqued' effect
just don't go well together. Even if 'antique' is
not the reason for the choice of an oxide wash, it
still seldom looks as good when shiny.

-Snail
(Not a fan of shininess anyhow.)