Edouard Bastarache Inc. on sat 1 may 04
Hello all,
contrary to an opinion emitted here last week (if I recall correctly),=20
saying you need a computer to calculate dilatation coefficients of=20
glazes, Smart explains how to do so by hand at :
http://perso.wanadoo.fr/smart2000/dilatation.htm
Naturally he also says it is much less diificult if you use a computer
programme such as Excel or MSWorks.
It would certainly be a good idea to do this by hand a few times to =
better
understand the procedure.
Later,
"Ils sont fous ces quebecois"
Edouard Bastarache
Irreductible Quebecois
Indomitable Quebeker
Sorel-Tracy
Quebec
edouardb@sorel-tracy.qc.ca
http://sorel-tracy.qc.ca/~edouardb/
http://perso.wanadoo.fr/smart2000/index.htm
http://www.digitalfire.com/education/toxicity/
Ron Roy on tue 4 may 04
Calculating glaze expansion/contraction is done from the % analysis of a
glaze - there is a wonderful article that was published by Mike Bailey and
David Hewitt in Ceramic Review (#113 & 114) in 1988.
There may be a copy of it on Davids web site - David? Mike?
There are instructions and sets of expansion factors
No you do not need a computer to do it but if you do it that way it takes
seconds - not hours.
Doing it by hand did not enhance my understanding of it - except to
understand that this kind of thing is best done by computers.
Find the % of each oxide in a glaze and multiply each by a factor from a
set of coefficients - pretty easy to understand.
I can't emphasize enough the usefulness of changing a recipe and getting an
instant read out of what happens to the calculated expansion of a glaze.
Adding silica in increments of one - seeing what happens to the expansion -
stopping where you need to be to stop crazing - would take hours by hand -
seconds using computer software. Better to spend those hours learning a
computer program.
Needless to say - one of the criteria for choosing a glaze calculation
program - it must calculate expansion as well as a molecular formula -
specifically the Seger molecular formula.
RR
>contrary to an opinion emitted here last week (if I recall correctly),
>saying you need a computer to calculate dilatation coefficients of
>glazes, Smart explains how to do so by hand at :
>
>http://perso.wanadoo.fr/smart2000/dilatation.htm
>
>
>Naturally he also says it is much less diificult if you use a computer
>programme such as Excel or MSWorks.
>
>It would certainly be a good idea to do this by hand a few times to better
>understand the procedure.
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Edouard Bastarache Inc. on tue 4 may 04
Ron,
Smart uses % molar, not % weight.
Also, if you remember a little bit of French you will see
there is a more complicated approach for boron, silica,=20
titanium dioxide and lead oxide than for the other oxides
in computing the "alpha coefficient"
Later,
"Ils sont fous ces quebecois"
Edouard Bastarache
Irreductible Quebecois
Indomitable Quebeker
Sorel-Tracy
Quebec
edouardb@sorel-tracy.qc.ca
http://sorel-tracy.qc.ca/~edouardb/
http://perso.wanadoo.fr/smart2000/index.htm
http://www.digitalfire.com/education/toxicity/
David Hewitt on wed 5 may 04
In message , Ron Roy writes
>Calculating glaze expansion/contraction is done from the % analysis of a
>glaze - there is a wonderful article that was published by Mike Bailey and
>David Hewitt in Ceramic Review (#113 & 114) in 1988.
>
>There may be a copy of it on Davids web site - David? Mike?
>
Yes. It is reproduced on my web site.
http://www.dhpot.demon.co.uk
Look under Pottery Techniques / Calculating Crazing
>There are instructions and sets of expansion factors
>
--
David Hewitt
David Hewitt Pottery
South Wales UK
Web:- http://www.dhpot.demon.co.uk
Ron Roy on fri 7 may 04
Hi Edouard,
The software I use uses % analysis to do it.
In chapter 5 of Mastering Cone 6 Glazes you will see 5 glazes that are used
to find the expansion/contraction of clay bodies. All were designed using
calculation software to get an even spread of coefficient of expansion
between the glazes. When I measured the glazes samples for expansion - the
space between each is remarkably even - as you can see from the published
dilatometer charts.
I was aware that solving glaze fit problems with calculation software was
viable - I've been doing it for potters for many years now. The surprise
was just how viable and accurate it is.
RR
>Ron,
>
>Smart uses % molar, not % weight.
>
>Also, if you remember a little bit of French you will see
>there is a more complicated approach for boron, silica,
>titanium dioxide and lead oxide than for the other oxides
>in computing the "alpha coefficient"
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
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