Mudslide Pottery on thu 14 jun 12
Can anyone tell me the expansion for this glaze? It's a cone 10 Spodumen=
=3D
e.=3D20
Thanks!! Geno
Custer F-Spar 30
Spodumene 20
EPK 12.5
Calcined EPK 12.5
Dolomite 20
Whiting 5
Tin Ox. 6
Bentonite 2
Edouard Bastarache on thu 14 jun 12
The results of calculating expansion values
depend on the method used:
http://www.flickr.com/photos/potier/46606941/in/photostream
From Glazechem
Custer F-Spar 30
Spodumene 20
EPK 12.5
Calcined EPK 12.5
Dolomite 20
Whiting 5
Tin Ox. 6
Bentonite 2
Na2O 0.04 Al2O3 0.58 SiO2 2.13
K2O 0.09 P2O5 0.00
MgO 0.30 TiO2 0.00
CaO 0.44 Fe2O3 0.00
Li2O 0.13 SnO2 0.11
Alumina:Silica ratio is 1.00:3.69
Neutral:Acid ratio is 1.00:3.88
Alk:Neut:Acid ratio is 1.00:0.58:2.25
Expansion: 68.1 x 10e-7 per degree C
Oxides causing abnormal expansion:
Li2O
Plejkore,
Edouard Bastarache
Spertesperantisto
Sorel-Tracy
Quebec
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http://edouardbastarache.blogspot.com/
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ronroy@CA.INTER.NET on thu 14 jun 12
Hi Geno,
Hard question to answer - it's a clay matte so any calculated
expansion is unreliable - it only works for glossy glazes. I could
measure it in my dilatometer if you must know.
The calculated expansion indicates (if it were a glossy glaze) it
might be on the verge of crazing on the cone 10 porcelain I use.
So much depends on the clay body if it's stoneware - if you can tell
me what the problem is I may be able to make some suggestions.
Custer has changed - not as much potassium as in the older stuff -
have things changed - using a new bag of Custer?
RR
Quoting Mudslide Pottery :
> Can anyone tell me the expansion for this glaze? It's a cone 10 Spodumen=
e.
> Thanks!! Geno
>
> Custer F-Spar 30
> Spodumene 20
> EPK 12.5
> Calcined EPK 12.5
> Dolomite 20
> Whiting 5
> Tin Ox. 6
> Bentonite 2
>
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