Maurice Weitman on tue 18 sep 07
Hello, Holly, and welcome to clayart.
You wrote:
>I am new to clayart and was hoping someone could help me with this glaze I
>have been testing. It is a smooth satin eggshell glaze that has a
>wonderful feeling surface and when colored it breaks nicely over textures.
>However, it is not durable (scratches easily). I would like to use it at
>least on the exterior surfaces of functional ware. Here is the recipe:
>
>Smooth Satin Eggshell base
>Custer Spar 46
>FF 3124 6
>EPK 80
>Dolomite 15.5
>Whiting 9
>Zinc Ox. 0.5
>Silica 7
>
>I'd like to try to make this glaze more durable. I don't mind if the
>surface texture changes some as long as it still breaks on textures.
That looks like an awful lot of EPK.
Also, (and this might not be a problem, but...) the ingredients add up to 164.
Putting these observations together, I'd like to suggest the following:
If the EPK were reduced to 16, the recipe would add up to 100 AND it
would fall more closely into the range of a better-melting cone 6
firing.
Let us know if there might be a typo in the recipe or what the source
is so that it can be checked.
Regards,
Maurice
Holly Holladay on tue 18 sep 07
Hey all,
I am new to clayart and was hoping someone could help me with this glaze I
have been testing. It is a smooth satin eggshell glaze that has a
wonderful feeling surface and when colored it breaks nicely over textures.
However, it is not durable (scratches easily). I would like to use it at
least on the exterior surfaces of functional ware. Here is the recipe:
Smooth Satin Eggshell base
Custer Spar 46
FF 3124 6
EPK 80
Dolomite 15.5
Whiting 9
Zinc Ox. 0.5
Silica 7
I'd like to try to make this glaze more durable. I don't mind if the
surface texture changes some as long as it still breaks on textures.
Any ideas?
Thank You,
Holly Holladay
Ivor and Olive Lewis on wed 19 sep 07
Dear Holly Holladay,
How high are you firing this glaze ?
Is there any reason why the sum of the weights of your ingredients is =
over 160 rather than 100 ?
I think that your mixture is not being fired to maturity. There is, in =
my opinion, insufficient flux to adsorb that quantity of Kaolin and the =
other two refractory materials derived from Dolomite and Whiting.
My experience tells me that good Satin eggshell surfaces can be had by =
using Wollastonite and Talc.
I suggest experimentation and would propose two stages. One is to line =
blend your Spar and your Boron frit to get the best melt at your regular =
firing temperature. Then use this blend as one of the ingredients in a =
6x6 test tile with Wollastonite and Talc bringing in your EPK as the =
fourth ingredient.
Lime Magnesia satin mat glazes of this type seem to break well over =
texture on a dark clay.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
Ron Roy on thu 20 sep 07
Hi Holly,
I am assuming the EPK is supposed to be 16 instead of 80.
Even so the glaze is probably eggshell because it's not melted enough at
cone 6. Adding more flux ( zinc or frit) will help out.
If all that makes sense let me know and I'll whip up a few line blends for
you to try.
Just keep in mind - eggshell is probably going to "scratch" because it's
rough to spoons.
RR
>Hey all,
>
>I am new to clayart and was hoping someone could help me with this glaze I
>have been testing. It is a smooth satin eggshell glaze that has a
>wonderful feeling surface and when colored it breaks nicely over textures.
>However, it is not durable (scratches easily). I would like to use it at
>least on the exterior surfaces of functional ware. Here is the recipe:
>
>Smooth Satin Eggshell base
>Custer Spar 46
>FF 3124 6
>EPK 80
>Dolomite 15.5
>Whiting 9
>Zinc Ox. 0.5
>Silica 7
>
>
>I'd like to try to make this glaze more durable. I don't mind if the
>surface texture changes some as long as it still breaks on textures.
>
>Any ideas?
>
>Thank You,
>Holly Holladay
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Holly Holladay on mon 26 nov 07
Sorry guys, I messed up typing out the glaze formula in my message.
The formula is:
Custer feldspar 46
FF 3124 6
EPK 16
Dolomite 15.5
Whiting 9
Zinc Ox. .5
Quartz 7
This is my adaptation of GA 18 in Mike Bailey's book Glazes Cone 6.
Those of you who own that book can view the original recipe. Maybe, I
didn't select the right substitutions when converting from English
ingredients.
I checked my glaze notes, and I didn't make up my test batches with my
typo from my original message (with 80 EPK). So that is good. However,
that means the glaze as stated above is still not durable and scratches
easily, as Ron thought it might with the formula corrected.
I don't have any of the glaze software programs, nor do i know much about
line blends, but if you send them to me with some explanation, I would
love to test them. After more testing, I will post my results to let you
all know if it can ever be more than a glaze for decorative ware.
Thank you, Thank you! for all the responses. Sorry again for my typo.
Happy potting,
Holly Holladay
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