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r & j ^ 6 glaze uk frit substitute tests - longish

updated wed 4 dec 02

 

Avril Farley on sun 1 dec 02


For all interested parties, especially UK based potters, I have been =
trialling Ron and John's glazes using straight frit substitution with =
mixed, but mostly excellent results.

I fired as near to the the suggested programme as possible with my kiln =
and on opening up cone six was exactly as the example, tip just =
touching the shelf and cone 7 just beginning to bend.

Glossy Base Glaze 1 and High Calcium Semi Matte base 1. Used Standard =
Borax Frit instead of FF 3134
Material Analysis

Silica 49.6
Alumina 7.5
Boron 18.1
Potassium 1.7
Sodium 8.9
Calcium 14.1
Despite the fact I think the batches I made were a little over watered =
the resulting fired glazes were perfect, notably Bright Sky Blue, =
Variegated Blue, Oatmeal and especially Variegated Slate Blue.

I also tried Raspberry on Limoge Porcelain with the same frit substitute =
- this would have been a perfect finish but I should have seived at =
least twice as there was some tin oxide reclumping which led to some =
(quite fetching really) white patches.=20

Excellent colour response to all my tests matching the illustrations =
perfectly.

Waterfall Brown does NOT sub well. I used Calcium Borate frit as a sub =
for FF3195. Inside a large bowl most of the glaze ran into the centre =
in a scummy mess. Half way up the pot the resemblence to J & R's book =
cover was quite similar, but the first 2 inches from the rim were very =
red brown, very shiny and blistered. Will have to try this one again =
after a reformulation.

It was a useful experiment and my thanks to Ron & John for their =
excellent book.

Avril in the Forest UK=20

Ron Roy on tue 3 dec 02


Hi Avril,

Thanks for this - just a few comments that may help with substitutions.

Your frit (below) has some alimina - frit 3134 does not - a way to get any
glazes closer to ours using it would be to decrease the the clay in the
recipe (best to do it using the molecular formula approach) - you would
also need to increas the silica.

Frit 3195 provides a lot more more boron and alumina than yours below - if
you would like me to do some substitutions for you let me know - include
the analysis for all the frits you can get them for.

RR

>For all interested parties, especially UK based potters, I have been
>trialling Ron and John's glazes using straight frit substitution with
>mixed, but mostly excellent results.
>
>I fired as near to the the suggested programme as possible with my kiln
>and on opening up cone six was exactly as the example, tip just touching
>the shelf and cone 7 just beginning to bend.
>
> Glossy Base Glaze 1 and High Calcium Semi Matte base 1. Used Standard
>Borax Frit instead of FF 3134
>Material Analysis
>
>Silica 49.6
>Alumina 7.5
>Boron 18.1
>Potassium 1.7
>Sodium 8.9
>Calcium 14.1
>Despite the fact I think the batches I made were a little over watered the
>resulting fired glazes were perfect, notably Bright Sky Blue, Variegated
>Blue, Oatmeal and especially Variegated Slate Blue.
>
>I also tried Raspberry on Limoge Porcelain with the same frit substitute -
>this would have been a perfect finish but I should have seived at least
>twice as there was some tin oxide reclumping which led to some (quite
>fetching really) white patches.
>
>Excellent colour response to all my tests matching the illustrations perfectly.
>
>Waterfall Brown does NOT sub well. I used Calcium Borate frit as a sub
>for FF3195. Inside a large bowl most of the glaze ran into the centre in
>a scummy mess. Half way up the pot the resemblence to J & R's book
>cover was quite similar, but the first 2 inches from the rim were very red
>brown, very shiny and blistered. Will have to try this one again after a
>reformulation.
>
>It was a useful experiment and my thanks to Ron & John for their excellent
>book.
>
>Avril in the Forest UK

Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513