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bad overglaze advice!!!!

updated mon 8 mar 04

 

S.E.W. on fri 5 mar 04


I am surprised at the posting that was written in regards to signing the =
bottom of your pots with overglaze. First, overglazes are NEVER applied =
to unfired glaze. If I am wrong, someone tell me. Maybe there is a =
technique that is used which requires overglazes to be applied to an =
unfired glaze in order to produce a specific result, but I am unaware of =
it. Overglazes are only applied to fired glazes. Also, my experience =
with overglazes has shown that they are somewhat costly and also require =
a completely seperate firing. As far as gold overglaze to be used to =
sign the bottom of your pots, GIVE ME A BREAK! I use gold, platinum, =
etc. on a majority of my work and I would never "waste" it on signing =
the bottom of my pieces. Once again this brings me back to the issue of =
money and funding. I don't have endless money to be able to justify =
using gold on the bottom of my pots because it makes my signature look =
pretty. I have come to learn that there are (just a few) people who =
don't understand this concept. I learned this when the "seconds" issue =
was discussed and there were those who couldn't possibly understand why =
we would sell our pieces that weren't "pretty" enough and that they =
should be thrown in the trash. Others understand the aspect of keeping =
themselves funded so they can keep doing what they love. Which brings me =
back to overglazes. If it isn't a matter of money and you are able to =
sign the bottom of your pots with gold, than go ahead. It probably is a =
beautiful way to show your signature. But please do it the right way. =
Don't apply them over unfired glaze, not to mention they are fired at =
nearly 15 cones cooler than underglazes. It seems that the differences =
between overglazes and underglazes need to clarified to those who don't =
know.
Rachel

Megan Ratchford on sat 6 mar 04


"It seems that the differences between overglazes and underglazes need to
clarified to those who don't know."

Hi Rachel!
I think this is a difference of terminology. I have students who call
gold and platinum overglazes and some who call iron ox solution overglazes.
I think you're right, there needs to be some sort of definition.
I would define overglazes as something applied over unfired glaze. I
would describe the gold and platinum as metallic lusters. Anyone else have
a take on this??

Happy Potting!!!
Megan Ratchford
Littleton, Colorado

Lori Leary on sat 6 mar 04


Whoa, Rachel!

If you read David's post carefully, you will see he is not talking=20
about real* gold*. Not all overglazes come in a bottle....
If you concoct a mixture of rutile, red iron oxide and glossy glaze,=20
brush it over a temmoku glaze (unfired ), the result will be vivid =20
gold in the brushed area. We're not talking transmutation here,=20
although it would be nice to turn rutile and iron into gold.

Lori L.

S.E.W. wrote

>I am surprised at the posting that was written in regards to signing the=
bottom of your pots with overglaze. First, overglazes are NEVER applied =
to unfired glaze. If I am wrong, someone tell me. Maybe there is a techni=
que that is used which requires overglazes to be applied to an unfired gl=
aze in order to produce a specific result, but I am unaware of it. Overgl=
azes are only applied to fired glazes. Also, my experience with overglaze=
s has shown that they are somewhat costly and also require a completely s=
eperate firing. As far as gold overglaze to be used to sign the bottom of=
your pots, GIVE ME A BREAK! I use gold, platinum, etc. on a majority o=
f my work and I would never "waste" it on signing the bottom of my pieces=
=2E Once again this brings me back to the issue of money and funding. I d=
on't have endless money to be able to justify using gold on the bottom of=
my pots because it makes my signature look pretty. I have come to learn =
that there are (just a few) people who don't understand this concept. I l=
earned this when the "seconds" issue was discussed and there were those w=
ho couldn't possibly understand why we would sell our pieces that weren't=
"pretty" enough and that they should be thrown in the trash. Others unde=
rstand the aspect of keeping themselves funded so they can keep doing wha=
t they love. Which brings me back to overglazes. If it isn't a matter of =
money and you are able to sign the bottom of your pots with gold, than go=
ahead. It probably is a beautiful way to show your signature. But please=
do it the right way. Don't apply them over unfired glaze, not to mention=
they are fired at nearly 15 cones cooler than underglazes. It seems that=
the differences between overglazes and underglazes need to clarified to =
those who don't know.
>
> =20
>

Tony Olsen on sun 7 mar 04


Rachel, Megan,
Here's a take on it,
I always (until this post anyway) considered any thing you put over the =
glaze after firing, that has an oil base, to be "China paint". Anything =
you put on the unfired glaze that matures at the same temp is know to me =
as overglaze. Mom did a bunch of China painting when I was a kid.
China paints are fired typically at 018 to 021. =20
Over glazes are fired to the same cone and at the same time as the glaze =
firing.
I don't know when China paints became known as over glaze, but searches =
of the net indicate that this terminology is in current use. So what is =
Majolica? colorants over glaze?

Here's one web definition:
----------------8<-----------------
What is majolica?=20
Majolica in the historic sense is earthenware with a white, =
tin-opacified,=20
viscous glaze, decorated by applying colorants (often with a brush, =
using=20
calligraphic brush work) on the raw glazed surface. The viscosity of the =

glaze restricts flow as the glaze melts, giving a glossy surface that=20
maintains the line quality of the surface decoration.=20
----------------->8---------------

Don't know if this helps, or confuses, but lusters, gold, and other oil =
based, low fired decorations will, by me, be referred to as China paint.

Stay muddy y'all!
Tony



neslot@houston.rr.com
http://tonyolsen.com/up/

Snail Scott on sun 7 mar 04


At 10:05 AM 3/6/04 -0500, you wrote:
>...Overglazes are only applied to fired glazes. Also, my experience with
overglazes has shown that they are somewhat costly and also require a
completely seperate firing. As far as gold overglaze to be used to sign the
bottom of your pots, GIVE ME A BREAK!...


Relax! There are more types of overglaze than ^018
gold luster in bottles. 'Overglaze' is a very general
term for a wide range of substances, applied with a
wide range of techniques. It most commonly describes
materials applied after the glaze is fired, such
as metallic lusters, enamels, china paints and the
like, but in theory could include any material
applied on top of a glaze and fired, which is not
also a glaze itself. The term (like 'underglaze',)
really says nothing about the nature of the material
used, but only its position in the glazing sequence:
underglazes underneath; overglazes on top. They
could even be identical recipes, too.

That's just one reason I prefer terms like 'engobe'
to 'underglaze': it describes the material instead of
the process. If I apply it to clay that will never
be glazed, calling it an underglaze is just silly,
even if it came out of a commercially-labelled jar
marked 'underglaze'. That's just another attempt by
manufacturers to save their hobby customers from
the need to think. Good for them, I guess, but if
you choose to use their (rather handy) products,
that doesn't mean you have to be bound by their
crutch-like nomenclature. Same for those metallic
lusters. You can use them an overglazes, but they
can also go on any adequately vitrified surface,
not just glaze, so why get in the habit of calling
them 'overglazes'?

Let your materials roam free! Don't let them get
stuck doing just one thing, just because you started
thinking of them by the name of a process instead
of by their identity. Hooray for Free-Range Dirt
Products!

-Snail