Fay & Ralph Loewenthal on mon 3 jun 02
Peter Ilsley in his books states that one can use vanadium=20
pentoxide to promote crystal growth in the glaze. It can=20
create lustrous metallic surfaces, and strangely formed=20
crystals, like star shaped. triangular and rectangular. The
problem is there is no indication of what quantity or=20
percentage of vanadium pentoxide needs to go into the glaze.
Do I use the percentages of copper or cobalt carbonates /=20
oxides that he uses in his recipies, or test a whole range from
.5% to 5%?=20
I want to use the vanadium pentoxide as I have about 500=20
grams and do not want to have it just lying around on the=20
shelf. It should give some stunning effects.
Kind regards from Ralph Loewenthal in CT SA.
Avril Farley on mon 3 jun 02
Hi Ralph
In my experience Vanadium works well with copper and iron. I have
experimented with all sorts of permutations of oxides, and find that if you
follow Peter Ilsely and Diane Creber's rule of a total of not more than 8%
of single or mixed oxides to 100% base glaze, you can get millions of
different colours. Let me also recommend Fara Shimbo's e book. She has
done an enormous amount of work with oxides in crystal glazes, and
generously offers the results of her research in a well thought out, well
planned e book.
It sounds to me as if you are becoming as fixated as I with this fascinating
glaze.
Regards
Avril in the Forest, UK
----- Original Message -----
From: "Fay & Ralph Loewenthal"
To:
Sent: Monday, June 03, 2002 8:48 PM
Subject: Macro Crystaline glazes
Peter Ilsley in his books states that one can use vanadium
pentoxide to promote crystal growth in the glaze. It can
create lustrous metallic surfaces, and strangely formed
crystals, like star shaped. triangular and rectangular. The
problem is there is no indication of what quantity or
percentage of vanadium pentoxide needs to go into the glaze.
Do I use the percentages of copper or cobalt carbonates /
oxides that he uses in his recipies, or test a whole range from
.5% to 5%?
I want to use the vanadium pentoxide as I have about 500
grams and do not want to have it just lying around on the
shelf. It should give some stunning effects.
Kind regards from Ralph Loewenthal in CT SA.
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Jocelyn McAuley on mon 3 jun 02
Hi Ralph,
Sounds like you are in full gear in regards to your crystal testing!
I have a Dan Turnidge source that I graciously received from someone on
clayart that has a mention on vanadium pentoxide:
"Vandium Pentoxide also helps enhance crystals. I first tried this
chemical in the amount of five parts. As a result the glaze was textured
with little mountains, raising 1/4 inch off the pot. Later tests showed
me that using 0.1 to 0.5 parts gave much better results. Crystals
produced with the use of vanadium pentoxide are blue to brown in
color. This is a good chemical to use as a color enhancer with cobalt or
other colorants."
Ralph, rereading your email describing lustrous effects and
triangular crystals seems to suggest that you are describing the
effects of molybdic oxide, *not* vandium pentoxide.
Herbert Sanders comments on molybdenum crystals in his text Glazes for
Special Effects. His comments are a bit numerous to quote here, but here
is a summery:
- the crystals are subtle, and a bit elusive.
- glazes containing molybdenum are opalescent when reheated.
- molybdenum fumes.
- 4% is a good amount to work with, however consider straight line blends
or even trianxial blends to find the amount that appeals to you.
- given the fuming, place similarly glazed pieces close together when
firing.
- try refiring a piece.
In general regards to testing, your idea of testing a range from 0.5%-5%
is defintely a good place to start. And don't forget to test in
combination with other colorants! It's easy to see how these test tiles
multiple and take over...
Have fun
Jocelyn
--
Jocelyn McAuley ><<'> jocie@worlddomination.net
Eugene, Oregon http://www.ceramicism.com
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