Paulette Carr on sat 26 mar 05
Wayne wrote:
I learned more about RIO from listening to him and examining the pot
he pulled from his pocket (and what a red that was, Jon!) in 20
minutes than I had learned in all the reading I've done for the past
four years. I had NO CLUE that there were differing grades and
percentages of RIO, all sold generically as "RIO" by different
suppliers. =20
Ok, Wayne and Jon, I will bite! Can you elaborate on the differing
grades, and qualities of ROI. What should I be looking for? Which
suppliers have different grades? I assumed that since these materials
were mined, rather than synthesized and purified, that there would be
variations... I would love to hear Jon weigh in on this. I have a
feeling that the more I know, the better my glazes will be.
Best regards,
Paulette Carr
Paulette Carr Studio
Member/Potters Council
St. Louis, MO
John Britt on sat 26 mar 05
Paulette,
This is one reason I love Insight software. Owning it allows you to look
at the Ceramic Materials database. You can just search for red iron oxide.
But you can also search on Google.
Try searching for =93red iron producers 4686=94
You will see this link:
http://www.elementispigments.com/PDF/NR%20Reds.PDF
These are two synthetic red irons, 4686 and 4284, that are sold by Laguna
(where Joe Koon=92s works) and Georgies Clay. I am sure other companies sell=
them too. (You will have to search in your area.) US Pigments sells them
as synthetic iron oxide.
They have a very small particle size (I think around 325 mesh).
Try them and you will be amazed!
One thing about the iron is that they list the percent iron as 84 or 86
(above) while others say it is 96%..etc. I don=92t know the specifics on how=
that is reported but there are conflicting amounts listed by different
sources.
I also know that synthetic yellow iron is very strong. (Sold by Standard
Ceramics) Neither of the ones list so far will cause speckling.
These new irons are used as pigments for cements and grouts .
You can also get natural red iron, Spanish red iron (produced by bacterial
digestion) black iron, yellow ochre, magnetite, Burnt sienna, Burnt umber,
Crocus Martus, etc.
I would try to Google them and see what you find. You can also look on
Laguna=92s site as they have all the MSDS sheets for the products they sell.=
I am sure someone who knows more than I will fill in the details. You can
also call your ceramics supplies and find out that they say.
Best of luck in the world of iron,
John Britt
www.johnbrittpottery.com
Kate Johnson on sat 26 mar 05
John Britt wrote:
http://www.elementispigments.com/PDF/NR%20Reds.PDF
These are two synthetic red irons, 4686 and 4284, that are sold by Laguna
(where Joe Koon's works) and Georgies Clay. I am sure other companies sell
them too. (You will have to search in your area.) US Pigments sells them
as synthetic iron oxide.
They have a very small particle size (I think around 325 mesh).
Try them and you will be amazed!
----
So, John, I might get better honey/amber glaze results with these than what
I'd been using? What I have now is NOT 325 mesh, I still get iron chunks
when I seive my glaze to 100. Just got some silkscreen fabric and made my
one seives, thanks to Miss Lili's suggestions, and we'll see how the glaze
does now. Our incomparible Snail sent me some new iron to try, but haven't
had the opportunity yet...(unfortunately, I have three different batches of
RIO now and not sure which is the one she sent me, go ahead, say
it--BONEHEAD..)
---
>I also know that synthetic yellow iron is very strong. (Sold by Standard
Ceramics) Neither of the ones list so far will cause speckling.
---
Yellow, yellow?? Hmmmm...so I might get closer to that gorgeous 18th C.
honey/amber with this??
---
>You can also get natural red iron, Spanish red iron (produced by bacterial
digestion) black iron, yellow ochre, magnetite, Burnt sienna, Burnt umber,
Crocus Martus, etc.
---
What I've gotten so far from most of these is still a redbrown color, not
the amber I'm aiming for. At least for the most part...
God I love this stuff...
Best--
Kate Johnson
http://www.cathyjohnson.info/
Art, History, Nature and More at Cathy Johnson's Cafepress--
http://www.cafepress.com/cathy_johnson/
Graphics/Fine Arts Press--
http://www.epsi.net/graphic/
John Britt on sun 27 mar 05
Kate,
I would ceratinly try many types of iron. Another way to learn about iron
is to take several base glazes and then add iron up to 20%.
You can do this by mixing up 500 grams of a base glaze (Glaze with
colorants removed) and running a line blend with iron. [Add 1% iron and
dip a tile, add another 1% and dip a tile (that is 2% total) then add
another 1% and dip, until you get to 20%]
As you saw in Joe's article he used many glaze bases and just added iron.
There is a copper red base, a kaki base, celadon/temmoku base and oil spot
base, a magnesium matte base, etc.
Also, Yellow ochre and yellow iron will not produce better yellows. As
soon as they are heated over 1000F (approximately) they will change to red
iron. (water of hydration in the yellow iron will burn off) Try calcining
different forms of iron yourself and see the results. Melt tests are a
great way to start to understand a material.
What you want, for an amber iron glaze is a low alumina, high alkaline
base. On page 138 of my book I have several recipes and iron line blends
to show this. Give it a try. (Careful they are runny)
Hope it helps,
John Britt
www.johnbrittpottery.com
Kate Johnson on sun 27 mar 05
Hi John...
>
> I would ceratinly try many types of iron.
I suspect I need to find out specifically what I'm buying, too...I've just
bought "RIO" from a couple of sources. No way from that to tell whether
some might be Spanish or manmade or what...
Another way to learn about iron
> is to take several base glazes and then add iron up to 20%.
>
> You can do this by mixing up 500 grams of a base glaze (Glaze with
> colorants removed) and running a line blend with iron. [Add 1% iron and
> dip a tile, add another 1% and dip a tile (that is 2% total) then add
> another 1% and dip, until you get to 20%]
I've sort of done that...I was having problems with speckling (early on,
like coarse ground pepper!) The last batch I mixed like crazy (in my
blender, even) and sieved repeatedly, then brushed it on--still got wee dark
streaks where the iron bits were. (At least they were more like hairs or
filaments, last time I tested.)
>
> As you saw in Joe's article he used many glaze bases and just added iron.
> There is a copper red base, a kaki base, celadon/temmoku base and oil spot
> base, a magnesium matte base, etc.
No, I missed the article...here, or in one of the magazines?
>
> Also, Yellow ochre and yellow iron will not produce better yellows. As
> soon as they are heated over 1000F (approximately) they will change to red
> iron. (water of hydration in the yellow iron will burn off)
Yep, I'd found that to be true, just wondered if there was something I
didn't know about.
Try calcining
> different forms of iron yourself and see the results. Melt tests are a
> great way to start to understand a material.
>
> What you want, for an amber iron glaze is a low alumina, high alkaline
> base. On page 138 of my book I have several recipes and iron line blends
> to show this. Give it a try. (Careful they are runny)
Thank you, I've been meaning to get hold of your book! And I'll ask my
usual question--are any of these low-fire glazes? I'm working with
earthenware, so need lower temperatures.
Many thanks!
Best--
Kate Johnson
http://www.cathyjohnson.info/
Art, History, Nature and More at Cathy Johnson's Cafepress--
http://www.cafepress.com/cathy_johnson/
Graphics/Fine Arts Press--
http://www.epsi.net/graphic/
katetiler on sun 27 mar 05
Right - budge up there, I just decoded that RIO means Red Iron Oxide!
(we put the clocks forward an hour here last night and I've only just
caught up...)
I'm still at the stage of buying commercial clear glaze and adding RIO
to it for my honey glazes, and I use a percentage of between 2.5% and
4% to give what I call 'mid-range' honey colour - something that gives
a mid yellow colour to the white slip and a terracotta brown to the
red clay, rather than the deep brown and almost toffee crackle colour
that I get when I push the RIO up to 5% strength.
BUT this is a progression for me, because I used to buy wholly
commercial honey glaze and 'water it down' by adding it about 40/60%
to a clear glaze, until the potters supplier I used change the Iron
Oxide to a yellow iron oxide - it was foul!
I had only ever seen pink powder glaze and all of sudden here was this
suspicious looking pale yellow stuff! I queried whether it was honey
glaze, mixed it and fired a kiln full or tiles and YEUCH! Horrid,
cloudy opaque butterscotch colour!
I can't say what the effect is using it when mixing your own glazes
from raw materials but as far as I'm concerned - RIO good, YIO NO!
I'm sticking to the ferrous stuff!
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