Wes Rolley on sun 27 feb 05
Diana Pancioli wrote:
> Are iron saturated glazes fired in oxidation called "Avventurine"?
> Or does that name apply to reduction fired iron saturates too??
Damn it, Diana, you got me started again. I don't really know what an=20
Aventurine glaze is, is supposed to look like or how you accomplish it.
A search left me with more questions:
First, there is a Rookwood reference:
http://www.p4a.com/itemsummary/27870.htm
Then, I found this on Lasse =D6stman's site:
http://www.stoneware.net/stoneware/ex1/exh1.htm (No. 7 in the list, and=20
click the image to enlarge).
Now these two "Aventurine" glazes do not look like each other.
So that does not tell me what makes a glaze into an "Aventurine".
I thought that I had it with a reference to the Matrix 2000 WWW site,=20
http://www.matrix2000.co.nz/Page14.htm, but was only more confused=20
because this characterized Aventureine's as "low Al2O3, High PbO and=20
KNaO2 in aventurine glazes." No mention of Iron at all but lots of lead.
I also found Jon Singer's WWW site where he details his journey "Along=20
the Red Tenmoku Trail"=20
(http://www.jonsinger.org/jossresearch/ceramics/glazes/redtenmoku.html)
as well as Aventuring Glazes.
I finally found a reference to iron at=20
http://www.frit.com.cn/glazeoxide.htm where they said "Most glazes will=20
dissolve more iron in the melt than they can incorporate in the cooled=20
glass. Thus extra iron precipitates out during cooling to form crystals.=20
This behavior is true both in oxidation and reduction. For example, a=20
typical mid-temperature fluid oxidation glaze of 8-10% iron will freeze=20
black with fine yellow crystals. Lower temperature glaze with their high=20
flux content can dissolve more iron (I.e. Aventurine)."
I would guess that it is only the micro-crystaline effect. The=20
characteristic of the semiprecious gem stone called Aventurine is that=20
it is (nearly) transparent quartz with shimmering effects from=20
inclusions of mica or hematite.
Now, I have uses of the right color with iron micro crystalline effect=20
that fire cone 8 electric. But, I would not call them aventurine in that=20
they are very opaque.
Wes
--=20
"I find I have a great lot to learn =96 or unlearn. I seem to know far to=
o=20
much and this knowledge obscures the really significant facts, but I am=20
getting on." -- Charles Rennie Mackintosh
Wesley C. Rolley
17211 Quail Court
Morgan Hill, CA 95037
(408)778-3024
http://www.refpub.com/
Wes Rolley on tue 1 mar 05
John Britt wrote:
> Wes,
>=20
> I have some samples of "Goldstone" on my website:
>=20
> http://www.johnbrittpottery.com/gallery.htm
>=20
> And I have recipes and firing instructions for Aventurine Glazes in my
> book in the "Crystalline" chapter (pg. 138 - 139)
>=20
> Hope it helps,
John, I am not sure if it would help or not. What I was trying to
communcate with my questioning of the usage of the terms tenmoku and now
aventurine is that there are a lot of commonly used words that mean
different things to different people and that we use them as if
everybody knew what they meant.
The range of effects and colors that can be achieved through the use of
one metal oxide as a "colorant" is quite remarkable, especially if that
oxide is iron.
As for aventurine, I could copy your glaze, fire it basically your way
in my kiln and I may or may not end up with what you would call an
aventurine glaze. Maybe I can take all of the aventurines, tea dusts,
etc. and just call them my flakey iron glaze.
--=20
"I find I have a great lot to learn =E2=80=93 or unlearn. I seem to know =
far too
much and this knowledge obscures the really significant facts, but I am
getting on." -- Charles Rennie Mackintosh
Wesley C. Rolley
17211 Quail Court
Morgan Hill, CA 95037
(408)778-3024
http://www.refpub.com/
John Britt on tue 1 mar 05
Wes,
I have some samples of "Goldstone" on my website:
http://www.johnbrittpottery.com/gallery.htm
And I have recipes and firing instructions for Aventurine Glazes in my
book in the "Crystalline" chapter (pg. 138 - 139)
Hope it helps,
John Britt
www.johnbrittpottery.com
John Britt on wed 2 mar 05
Wes,
I guess we agree on the fact that words have many different meanings, and
that not everyone understands them all. (including me). But I don't think
that this is at all unusual. This is very common.
I don't think that using the term Temmoku to mean an iron brown/black
glaze that breaks to rust on the egde is incorrect or a misnomer.
And I most certainly think that you could take the glazes I give you and
fire them and get very similar results. I will hold up Jennifer Boyer of
Thistle Hill Pottery as an excellent example.
In fact, if you fire the Aventurine glazes in the book I am sure you would
be amazed!
Best to you,
JOhn Britt
www.johnbrittpttery.com
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