Paul Lewing on wed 12 jan 05
on 1/12/05 11:28 AM, Marilu at cobblestonecottage@EMAIL.COM wrote:
> Can someone tell me if I add 5 %
> silica and use 20% G200 instead
> of spodumene if the recipe
> will be okay? It makes the percentage
> 105% instead of 100.
Marilu, there's nothing magic about a recipe adding up to 100. It makes no
difference if you're mixing up 105 g. batches, you just have a little more
glaze.
If you want your new 105 g batch to add up to 100, just divide the amount
for each ingredient by 105, and multiply that number by 100. However, in
this particular recipe, the amounts then won't be those nice round numbers.
Paul Lewing, Seattle
Marilu on wed 12 jan 05
Hello
I have a recipe from the archives-
which is listed below with RR response,
that I am trying to figure out.
Can someone tell me if I add 5 %
silica and use 20% G200 instead
of spodumene if the recipe
will be okay? It makes the percentage
105% instead of 100. So I am not sure
if I am understanding what is being said. I
want to use it on goblet rims. Thank you-Marilu
Base Glaze ^6... a semi-glass white
Frit 3134 20 %
dolomite 20 %
spodume 20 %
kentucky (!?) ball clay *20 %
flint/silica 20 %
Ron Roy's response:
Ron Roy on wed 18 mar 98 (ronroy@astral.magic.ca)
This first glaze (Base glaze ^6) is a little short of silica to be
considered durable at cone 6 - not too fare off - adding 5% silica fixes it
up just fine - Using ball or kaolin will not affect the glaze either way
very much from a durability or expansion standpoint. I doubt if the
Spodumene is necessary - it's expensive and the only reason to use Lithium
in a glaze would be to try and lower the expansion - that won't work in
this glazes because of the amount other alkalies - so try it with Custer or
G200 instead of the spod - I think you will not see much, if any
difference.
Ron Roy on thu 13 jan 05
Hi Marilu,
The addition of 5% silica was to improve durabilty - if it's not going to
be used as a liner you may not wish to do that - I suggest you try it to
see if the glaze is still looking good anyway.
Using spar instead of spodumene raises the expansion to a level which would
not worry me - no harm in doing a line blend - with spodumene in one and
spar in the other.
Low expansion glazes can result in flakes of razor sharp glaze coming off
fired pots - you said you wanted to use this glaze on rims - I say watch
out!
The main thing is to test the glaze with the spodumene for fit - if you
want to know how to do that let me know.
RR
>I have a recipe from the archives-
>which is listed below with RR response,
>that I am trying to figure out.
>Can someone tell me if I add 5 %
>silica and use 20% G200 instead
>of spodumene if the recipe
>will be okay? It makes the percentage
>105% instead of 100. So I am not sure
>if I am understanding what is being said. I
>want to use it on goblet rims. Thank you-Marilu
>
>Base Glaze ^6... a semi-glass white
>Frit 3134 20 %
>dolomite 20 %
>spodume 20 %
>kentucky (!?) ball clay *20 %
>flint/silica 20 %
>Ron Roy's response:
>Ron Roy on wed 18 mar 98 (ronroy@astral.magic.ca)
>This first glaze (Base glaze ^6) is a little short of silica to be
>considered durable at cone 6 - not too fare off - adding 5% silica fixes it
>up just fine - Using ball or kaolin will not affect the glaze either way
>very much from a durability or expansion standpoint. I doubt if the
>Spodumene is necessary - it's expensive and the only reason to use Lithium
>in a glaze would be to try and lower the expansion - that won't work in
>this glazes because of the amount other alkalies - so try it with Custer or
>G200 instead of the spod - I think you will not see much, if any
>difference.
>
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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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