boobyagga@juno.com on wed 25 jan 06
wow this is the first time the forum has ever disappointed me. about a w=
eek ago i asked for help on oxides and didnt get a single response. very=
odd. dont know so i am asking again.
recently i got some great metal oxides. copper carb, cobalt carb, red ir=
on oxide, black iron oxide, yellow iron oxide, and rutile. i understand =
most of these can be used in lowfire saggar and pit firing which is what=
ive been mainly interested in. ive used real iron fillings and real cop=
per chunks and wires and gotten great effects. however as i use these po=
wdered forms they do not color the pots or stick to them after the firin=
g. ive tried everything from washes to dry chemicals to mixing them into=
thick soaps to adhere better to the pot. ive used saggars of clay and f=
oil. ive burned them from 1100 degrees F to 1833 F and the results are g=
enerally the same. i get the pot out and the colors have changed slightl=
y but the atmosheric look isnt there and when i wash the pot almostall o=
f the oxides come off as if they were just sitting on the surface leavin=
g just a slight tint behind on the pot. why would these do that when the=
se are specially ground/formulated to be better for these pots. i know p=
eople use these. ive read plenty of books about them and thats what prom=
pted me to buy them. ive had great success with wires and chunks of meta=
l and thought that things would only improve as i got purer and powdered=
chemicals but have only been met with disappointment. =
so i would like any tips and tid bits from anyone. kinda stinks to buy 1=
00 dollars worth of powder and have very limited success. =
thanks everyone.
jason palmer
Marcia Selsor on wed 25 jan 06
try adding some salt into you saggars with the oxides. I'd go at
least to 1600 F.
If you are doing sawdust firings, half salt and half copper works
well. I put newspaper and sticks and sometimes charcoal brickets into
the barrel.
Hope you have some success.
Marcia Selsor in Montana
where people are wearing sandals and there is no charcoal available
in the stores. Heat wave!
On Jan 25, 2006, at 6:02 PM, boobyagga@juno.com wrote:
> wow this is the first time the forum has ever disappointed me.
> about a week ago i asked for help on oxides and didnt get a single
> response. very odd. dont know so i am asking again.
Steve Slatin on thu 26 jan 06
Jason --
I was hoping someone with some actual knowledge would jump
in here, but so far no luck ... I do NOT have any actual knowledge,
but I have some opinions you may find amusing.
First, you got some carbonates and oxides. They are, as you
know, fine powders. You applied them to semi-dry or bisqued
clay and fired them to low temperatures, and they do not adhere
to the surface of the vessel following the firing. No glaze,
right?
In fact, they do not adhere or show effects as well as the larger
amounts of 'rougher' supply of copper wire and iron filings and all
that.
This is predictable.
Raw clay doesn't readily vitrify, especially not at the lower temps
you're firing at. Most oxides also won't melt at these temps. The
particles of oxides and so on that you're applying to the surface of
the pots won't form a chemical bond with anything, and, even after
firing, will essentially just be sitting on the surface.
When you come along with a piece of steel wool of whatever,
you just scrape the top surface of the pot off, and the fine layer
of particles of oxide along with them.
Big honking chunks of iron filings, by comparison, get dug in
deeper, and leave more behind for surface effects. If you want to
get more utility out of your oxides, work them into your clay, or
mix them with a bit of slurry from your throwing or hand working
and 'paint' the mix onto the outside of your pots. Or, use them
as underglazes and dip or brush some clear glaze over them.
"boobyagga@juno.com" wrote:
wow this is the first time the forum has ever disappointed me. about a week ago i asked for help on oxides and didnt get a single response. very odd. dont know so i am asking again.
recently i got some great metal oxides. copper carb, cobalt carb, red iron oxide, black iron oxide, yellow iron oxide, and rutile. i understand most of these can be used in lowfire saggar and pit firing which is what ive been mainly interested in. ive used real iron fillings and real copper chunks and wires and gotten great effects. however as i use these powdered forms they do not color the pots or stick to them after the firing. ive tried everything from washes to dry chemicals to mixing them into thick soaps to adhere better to the pot. ive used saggars of clay and foil. ive burned them from 1100 degrees F to 1833 F and the results are generally the same. i get the pot out and the colors have changed slightly but the atmosheric look isnt there and when i wash the pot almostall of the oxides come off as if they were just sitting on the surface leaving just a slight tint behind on the pot. why would these do
Steve Slatin --
This space for rent
---------------------------------
Do you Yahoo!?
With a free 1 GB, there's more in store with Yahoo! Mail.
Ivor and Olive Lewis on fri 27 jan 06
Dear Jason,=20
I think you have just hit the knowledge gap, what marathon runners call =
"The Wall". I am uncertain as to the source of your knowledge but there =
appears to be a mismatch between what you believe you have read and what =
you were reading. Hitting "The Wall" is a major event in personal =
development.
Yes, all of the materials you have bought can be used to create colour =
in pottery. A good investment. But the caveat is this in the case of =
Oxides and Carbonates, they are used to colour clay bodies and glaze. =
They do not volatilise, then migrate across space to tint your clay. =
They cannot be used for vapour glazing, not without the help of some =
sort of Catalyst or Reactant. Sager Firing relies on the volatilisation =
of materials in an enclosed space for its effectiveness.
Now it is years since I did any low temperature saggar firings and I =
have never done anything with a pit though a student teacher who stood =
in for me when I was at the 1988 Sydney conference did that with a group =
of my high school students. Those students were not impressed. At the =
1983 Adelaide conference I watched a demo of raku and the operator used =
a pressure garden spray to project a mist of Copper Sulphate solution on =
his pots as they went into the reduction chamber. Result, vivid intense =
reds, very impressive
If you are going to do things in the 700 to 1000 =BA C range you have to =
choose materials that will melt or volatilise at those temperatures and =
react with you clay. Most oxides do not respond in this way. Very few =
liquefy below Cone 6. Copper wire melts at about 1060=BA C which is why =
you got good results. Silver wire would do similar things but you would =
get yellow browns instead of red browns, but you are looking at a dollar =
a gram for Silver nitrate. Your other option is to get water soluble =
salts and spray them onto the clay, or soak your organic materials in =
their solutions to get a reaction between the ash and the salt.
I suggest you buy just an ounce or so of the Chlorides of the metals you =
have chosen and test these. Then get back to the folk you are trying to =
emulate and request a demo and instructions.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
Snail Scott on fri 27 jan 06
At 06:02 PM 1/25/2006 GMT, you wrote:
>recently i got some great metal oxides. copper carb, cobalt carb, red iron
oxide, black iron oxide, yellow iron oxide, and rutile. i understand most
of these can be used in lowfire saggar and pit firing which is what ive
been mainly interested in. ive used real iron fillings and real copper
chunks and wires and gotten great effects. however as i use these powdered
forms they do not color the pots or stick to them after the firing.
You are seeing the effects of fumes from those
materials, not bits of the actual material.
The oxide forms of these metals will not necessarily
fume the same as the pure metallic form. They
are generally refractory, too, and will not stick
to clay even if applied directly to it, unless it
gets MUCH hotter than a standard pit/saggar fire.
They are more often used as colorants in recipes
which contain fluxes to help them melt and fuse to
the clay. They won't stick without some kind of
thing to melt them on. If you do get a flux to mix
with the oxides, though, it will go on like a paint
or stain, and not look like a fume effect at all
unless you paint it on to look that way. That
doesn't sound like what you had in mind. Sorry.
I don't have a good solution for you.
-Snail
earlk on fri 27 jan 06
On Fri, 2006-01-27 at 10:22 +1030, Ivor and Olive Lewis wrote:
> Your other option is to get water soluble salts and spray them onto
> the clay, or soak your organic materials in their solutions to get a
> reaction between the ash and the salt.
>
> I suggest you buy just an ounce or so of the Chlorides of the metals
> you have chosen and test these.
Many metal carbonates, and oxides too, will dissolve
in vinegar forming the metal acetate. This solution
could be sprayed, wiped, brushed or splattered on
your pots to develop some color.
earlk...
bothell, wa, usa
Ivor and Olive Lewis on sun 29 jan 06
Dear Earl,
A good point about the use of a good strong vinegar
Two score years ago when I was doing the course on Studio Practice we =
made our saggars out of slabs and those of us who were able threw them =
from a good well grogged refractory fire clay.
Then we moulded small pockets on the inner walls. These were made to =
contain a couple of grams or so of Soda or common salt as well as other =
metallic chlorides. The fumes from these chemicals gave good blushing on =
white slip surfaces.Major problems would happen if the saggars were =
overheated. Great way to generate frothy lava.
I still have one or two odd pieces kicking around the shard pile.
Best regards,
Ivor
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