Eva Funderburgh on wed 15 feb 06
Hi,
This is my first post to clay art, so if it accidentally ends up in the
wrong section, please forgive me.
My name is Eva Funderburgh. I am an amateur potter who is also working a
chemistry lab at the University of Washington. I've been helping them
research the spherical crystalline forms in macro crystalline glazes, which
are technically known as spherulites. Spherulites are a form that consists
of tiny needle like crystals radiating out from a disordered center,
creating a spherical growth. No one understands why they grow the way they
do, despite the fact that they form in a variety of different occasions.
They even form in the plaques in the brains of Alzheimer's patients.
I've been trying to examine molybdenum crystalline glazes, to see if
they'd be useful to us. I've been working from a collection of recipe's in
Herbert H. Sanders's "Glazes for special effects". However, I have yet to
have any luck. Does anyone have any experience with molybdenum, or
recommendations on trying the different recipes? Should I be giving the
molybdenum glazes a soak time similar to glazes with zinc silicate
crystalline glaze?
Thank you very much you for any help,
Eva Funderburgh
Jon Pacini on thu 16 feb 06
Greetings All, Hi Eva
I have worked with the Molybdenum glazes from the Sanders book since back in
the 70's. I've had the best luck with them in the ^4-5 range. What has
worked for me is to fire them in a tightly enclosed sagger.
What seems to happen with molybdenum when heated is that it goes from a
solid directly to a gas and then back to a solid on cooling. If you don't
keep it in an enclosed space when it turns to a gas it volitalizes and
dissipates.
The crystals form frost or snowflake like structures in his lead glazes and
they are very delicate and subtle. They can also take on a rainbow
iridescence. I've gotten them as big as a half dollar, but that's about it
and soaking doesn't seem to help. They are very elusive to say the least.
Otto Natzler worked with similar Glazes in the late 70's early 80's and
there was an article in CM at that time regarding them. You might try to
find it, though I don't remember the exact date of it.
E-mail me directly if you are interested -- jpacini@lagunaclay.com
Best regards,
Jon Pacini
Clay Manager
Laguna Clay Co
Des & Jan Howard on fri 17 feb 06
Eva
Check this site out
http://www.bulldogpottery.com/Mo%20description.htm
Des
Eva Funderburgh wrote:
> I've been trying to examine molybdenum crystalline glazes, to see if
>they'd be useful to us. I've been working from a collection of recipe's in
>Herbert H. Sanders's "Glazes for special effects". However, I have yet to
>have any luck. Does anyone have any experience with molybdenum, or
>recommendations on trying the different recipes? Should I be giving the
>molybdenum glazes a soak time similar to glazes with zinc silicate
>crystalline glaze?
>
>
--
Des & Jan Howard
Lue Pottery
LUE NSW 2850
Australia
Ph/Fax 02 6373 6419
http://www.luepottery.hwy.com.au
Ivor and Olive Lewis on fri 17 feb 06
To reinforce what Jon Pacini has told us, Molybdenum trioxide Sublimes, =
that is changes directly form the solid to a gas at 1155 deg C. (2111 =
deg F).
Best regards,
Ivor Lewis.
Redhill,
South Australia.
=20
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