Geoffrey Gaskell on mon 28 apr 03
What is the purpose of flint in glaze mixtures? Is it known by any other =
name? What different substances would make a good substitute, if no =
flint happened to be lying around handy?
Geoffrey Gaskell
Marcia Selsor on mon 28 apr 03
Flint a.k.a. silica or quartz is a prime ingredient in glaze. It is the
"glass" maker. The ration between the alumina and silica determine the
texture of the glaze and the ratio between the fluxes and silica
determine the melting point. That is an extemely reduced definition of
what it does in the glaze.
Hope this helps.
Marcia
Geoffrey Gaskell wrote:
> What is the purpose of flint in glaze mixtures? Is it known by any other name? What different substances would make a good substitute, if no flint happened to be lying around handy?
>
> Geoffrey Gaskell
>
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--
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Lily Krakowski on mon 28 apr 03
Be a darling. Put on your shoes, your coat, your hat. Go to the Public
Library. Get a book on basic pottery. There is Kenny, Birks, Rhodes,
Cardew, Casson. Or you can go to your local bookstore and BUY a book. Or
you can go on the internet. Either to a web site or ALIBRIS.
Geoffrey Gaskell writes:
> What is the purpose of flint in glaze mixtures? Is it known by any other name? What different substances would make a good substitute, if no flint happened to be lying around handy?
>
> Geoffrey Gaskell
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.
Lili Krakowski
P.O. Box #1
Constableville, N.Y.
(315) 942-5916/ 397-2389
Be of good courage....
Dave Finkelnburg on mon 28 apr 03
Geoffrey,
Flint is a source of silica. Use silica when a recipe calls for flint.
The word flint is used, unfortunately, as a synonym for silica when true
flint is usually less pure. For example, Tony Hansen uses an analysis of
93% silica, 3.5% calcium oxide, 3.5% LOI (loss of weight on heating in a
glaze), in his Insight glaze calculation software. He uses an analysis of
100% silica, zero LOI, for silica.
Flint is a silica source found in sedimentary rock. It is usually
contaminated with limestone and organic matter. Many recipes of
British/European origin call for flint. If you are fussy about duplicating
such a recipe, you may want to resort to some calculation when substituting
silica for it.
Good potting!
Dave Finkelnburg
----- Original Message -----
From: "Geoffrey Gaskell"
What is the purpose of flint in glaze mixtures? Is it known by any other
name? What different substances would make a good substitute, if no flint
happened to be lying around handy?
Roly Beevor on mon 28 apr 03
Geoffrey Gaskell writes:
>
> > What is the purpose of flint in glaze mixtures? Is it known by any other
name?
Lily Krakowski replies:
> Be a darling. Put on your shoes, your coat, your hat. Go to the Public
> Library. Get a book on basic pottery. There is Kenny, Birks, Rhodes,
> Cardew, Casson. Or you can go to your local bookstore and BUY a book. Or
> you can go on the internet. Either to a web site or ALIBRIS.
Geoffrey,
Don't be put off by Lily's reply, yours is a perfectly reasonable question,
I didn't know that flint was cryptocrystalline native silica until I looked
it up. Hamer and Hamer say: ' Flint is almost interchangeable with
quartz...flint should melt more readily because of its calcium oxide
content.. however it does not always appear to do so...two types of silica,
flint and quartz are sometimes used to deliberately introduce two types of
silica nuclei for jun and other crystalline effects...'. They may well have
Hamer and Hamer in your local library but a basic book won't always give you
the information you need.
Roland
Earl Brunner on mon 28 apr 03
What Lily is saying though is that if someone doesn't even have enough basic knowledge about glazes to know what some of the basic parts of a glaze are they do need a good book or two. The basics of glaze formulation and the understanding of the chemistry involved can be daunting to a beginner, I know it was for me. That was so long ago for some of us that I think we forget. I didn't know much chemistry when I started to learn about glazes back in the late 60's early 70's. Glen Nelson's CERAMICS and Daniel Rhodes, CLAY and GLAZES for the POTTER were my Bibles. Did my first glaze calculations using a slide rule. I remember being totally amazed that BASES, NEUTRALS, and ACIDS were so obliging and arranged themselves into those nice neat columns that happened to basically relate to their relationships in a glaze............
Roly Beevor wrote:Geoffrey Gaskell writes:
>
> > What is the purpose of flint in glaze mixtures? Is it known by any other
name?
Lily Krakowski replies:
> Be a darling. Put on your shoes, your coat, your hat. Go to the Public
> Library. Get a book on basic pottery. There is Kenny, Birks, Rhodes,
> Cardew, Casson. Or you can go to your local bookstore and BUY a book. Or
> you can go on the internet. Either to a web site or ALIBRIS.
Geoffrey,
Don't be put off by Lily's reply, yours is a perfectly reasonable question,
I didn't know that flint was cryptocrystalline native silica until I looked
it up. Hamer and Hamer say: ' Flint is almost interchangeable with
quartz...flint should melt more readily because of its calcium oxide
content.. however it does not always appear to do so...two types of silica,
flint and quartz are sometimes used to deliberately introduce two types of
silica nuclei for jun and other crystalline effects...'. They may well have
Hamer and Hamer in your local library but a basic book won't always give you
the information you need.
Roland
Earl Brunner
e-mail: brunv53@yahoo.com
Geoffrey Gaskell on tue 29 apr 03
Thanks to all who responded including those who advised me to do some basic
research for myself. At the time I fired off my questions, clearly labelled
for beginners, I had immediate access to email, but not to the internet or
to any useful books. Sometimes when I get bursts of enthusiasm I want the
answers almost then and there. Not only has the list answered my questions
more than adequately, but I have now also borrowed as soon as the local
library opened "The Potter's Dictionary of Materials and Techniques" (Frank
Hamer). These sources told me everything I specifically wanted to know
including the chemical formula (which is the only unambiguous way to
describe minerals, elements, gases etc).
Being the sort of person I am (one who ultimately wishes to be thorough in
his enquiries, investigations & understanding of things), I will now absorb
myself in the careful study of the book by Hamer and other books such as
Deer, Howie & Zussman "Introduction to the Rock Forming Minerals" and
general introductory chemistry books in order to teach myself the things I
believe I will need to know regarding the structure, chemistry, optical &
physical properties, distinguishing features & paragenesis of minerals
(which is what I would normally do, when I consider that I have everything
needful readily to hand).
Geoffrey Gaskell
Carol Tripp on tue 29 apr 03
This source hasn't been mentioned on Clayart recently but when I was brand
new to glaze chemistry, I found it to be perfect. Go to
http://art.sdsu.edu.ceramicsweb/ and click Education, then scroll down to
Class Materials and Education and click Class Materials and Technical
Handouts. This will give you the Robert Fromm Glaze and Clay Turtorial.
Print it out and read it over and over until you understand it. You don't
even have to get dressed to do it. ;-)
Have fun.
Best regards,
Carol
Dubai, UAE
>Geoffrey Gaskell writes:
> >
> > > What is the purpose of flint in glaze mixtures? Is it known by any
>other
>name?
>
>
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Fredrick Paget on tue 29 apr 03
Corrected URL - See below
>This source hasn't been mentioned on Clayart recently but when I was brand
>new to glaze chemistry, I found it to be perfect. Go to
>http://art.sdsu.edu/ceramicsweb/ and click Education, then scroll down to
>Class Materials and Education and click Class Materials and Technical
>Handouts. This will give you the Robert Fromm Glaze and Clay Turtorial.
>Print it out and read it over and over until you understand it. You don't
>even have to get dressed to do it. ;-)
>Have fun.
>Best regards,
>Carol
From Fred Paget, Marin County, California, USA
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