Stephani Stephenson on tue 8 mar 05
hello Lili and Kate
ah so you want a clear !My apologies, I first thought you were after a
buttery opaque type of glaze.
following are some of the Material definitions of some the frits
which, by themselves, had a fairly clear melt, on red terracotta at
cone 04 , in my tests . 3134 and 3269 had some milkiness.
Looking at the % helps me visualize the differences among the frits
and think about color response.
also I found that using straight RIO under or over or in these always
fell short of what I wanted... I started using stains, even combos of
rutile, chrome browns, & some stains with iron to get more consistent
, warmer tones. I still have not carried through on these tests to my
satisfaction.
also you might want to experiment with the following , from Pete
Pinnell:
this use to be a nice glaze, when we had the old gray spod,
Now , with the white sugary Aussie spod , it does give an initially
less interesting, but decent clear base which may prove helpful..gives
a bit of a satin sheen...of course gerstley is still in there..and one
occasion , on one claybody , I saw shivering with this glaze...
as usual, results depend so much on what kind of clay, and also what
kinds of slips the glaze interacts with. In fact more and more, with
my own experiments, I think tinkering with the underlying slip may be a
key factor in arriving at the right look and feel.
Pinnell 04-6 base
Spodumene 50
Gerstley 30
flint 20
also the base I initially started with was the simple
F. Carleton Ball base
Frit 3134 70
EPK 15
Silica 15
following are FRITS: From Insight Materials Database( %)
FRIT 3110 with all that sodium, high co- efficient of expansion
CaO .3%
K2O 2.3%
Na2O 15. %
Al3.7%
B2O3 2,6%
SiO2 69.8%
FRIT 3195
CaO 11.2%
Na2O 6 %
Al2O3 12.4%
B2O3 23%
SiO2 47.4%
FRIT 3134
CaO 21.1 %
Na2O.317%
B2O3 23.1%
SiO2 46.5%
FRIT 3269
CaO .1%
K2O 8.1%
Na2O 11.1%
ZnO 1 %
Al2O3 13.2%
B2O3 15.2%
SiO2 49.7%
I was also starting to use Frit 3270 in a glaze to try to shift the
color response. I don't have the breakdown handy , but 3270 was
higher either in potassium or magnesium or both, and had a lower %
calcium.
but, alas, Ihear 3270 has been discontinued
hope your quest is fruitful!!!!
Stephani Stephenson
steph@revivaltileworks.com
http://www.revivaltileworks.com
Kate Johnson on wed 9 mar 05
Hi Stephani and list...
> hello Lili and Kate
> ah so you want a clear !My apologies, I first thought you were after a
> buttery opaque type of glaze.
Well, I can certainly foresee a time when I'd LOVE that, but I think both
Lili and I, along with Rudy, Kate Tiler, and a few others are dealing with
tinting properties in a transparent glaze.
> also I found that using straight RIO under or over or in these always
> fell short of what I wanted...
I've gotten some decent color in a clear glaze base with just RIO, but still
need to find a much finer seive than I'm using. Getting peppergrains
suspended in the light honey color glaze. I don't believe I'll be able
to get a rich _amber_ with RIO, but light honey is nice. (Oddly, sometimes
the color was closer to tan--same glaze, same mix, different firing.
Pottery IS alchemy, isn't it?!)
I started using stains, even combos of
> rutile, chrome browns, & some stains with iron to get more consistent
> , warmer tones. I still have not carried through on these tests to my
> satisfaction.
That's the problem I had with stains, or one of them...most of them are
opaque and so cloud the resultant tint over the decorative slips.
>
> as usual, results depend so much on what kind of clay, and also what
> kinds of slips the glaze interacts with. In fact more and more, with
> my own experiments, I think tinkering with the underlying slip may be a
> key factor in arriving at the right look and feel.
I'm sure that does affect it! So far I'm using the same claybody (Flint
Hills Red Earthenware) and the same slip (white earthenware, I believe also
Flint Hills) that I started out with, on the theory that I need to get THOSE
down before I wander off too much into other things. So far the fit between
the body and the slip has been fine (if my timing is right.)
>
> following are FRITS: From Insight Materials Database( %)
>
> FRIT 3110 with all that sodium, high co- efficient of expansion
Blast. I'm afraid you're over my head already. This being the frit I have
on hand, naturally I'm curious...is a high co-efficient of expansion a bad
thing? Cause crazing? Que?
> hope your quest is fruitful!!!!
Many thanks, and for your generous sharing of recipes! I just keep pushing
that boulder uphill...or will as soon as I have time to get back to it.
More test tiles in my future...and I'll report back...
Best Regards,
Kate Johnson
http://www.cathyjohnson.info/
Art, History, Nature and More-- http://www.cafepress.com/cathy_johnson/
Graphics/Fine Arts Press-- http://www.epsi.net/graphic/
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