Susan Wagener on fri 14 nov 97
Thanks to all with your advice on changing a ^10 to a ^6 recipe. I've
started looking for other ^5-^6 recipes...such as a good clear base and matt
base to start with and have seen several posted recently. Before I posted
the previous message about lowering a firing temp of a recipe (which should
have acutally read lowering to ^5 not ^6) I had already purchased the book
The Potter's Palette. It has numerous pictures and was easy for me to
understand...since I don't have a degree in chemistry. Here is the base
recipe they have in the book and to this base I can add the colorants to
make the colors they show throughout the book. It says this base can be
fired in both oxidation and reduction, gives the best overall oxide response
together with good craze resistance. I thought it would be good for me as a
beginner...it sounds easy and I could basically follow the charts and
instructions with the colors of the tiles they have printed. So...can this
base recipe be easily adjusted to a ^5 range or should I try some of the
others that have been posted and add some of the colorants as pictured in
the book. I'm looking at several other books...but as of tonight...this is
the one glaze book I have. More are on order but I'd like to get started.
Here is the recipe... (From The Potters Palette)
Feldspar/Dolomite Glazes Temp 2372 F/Cone 10
Parts
Dry weight
Potash feldspar 50
Dolomite 20
China Clay 20
Bone Ash 10
----
100
This glaze is used for dilution, opacifiers, and crossblending. Alone, it
has a smoooth, semiopaque surface according to the book.
Then for instance I can add 5% Tin to the base glaze for a light blue glaze.
My clay is from Amaco - Porcelain Clay - No. 65. I low fire bisque to ^05
and then glaze fire to ^5.
So what's a new glaze maker to do? Throw the book out (or hand it off to
someone who fires to ^10)? I was so certain it would be as easy as it
sounded in class to adjust the base recipe. I'd like to get started making
glazes this week-end...I just hope I haven't jumped in over my
head...especially since I have all these chemicals now in their storage
containers sitting in my studio area of the basement. I still have the
pre-made glazes as fall back...I was just hoping to be able to be more
creative in the finishing of my pieces.
I thank you ahead of time for your input. Your patience with beginners
questions is most appreciated!! I hope this time next year I won't consider
myself a beginner...but be enthusiastic over my accomplishments with my
glaze making - thanks to all of you!
Susan Wagener
Puffin Pottery
Bloomington, IN
swagener@redridge.com
Kathi LeSueur on sun 16 nov 97
Changing a glaze recipe to lower its firing temperature while keeping its
surface properties is very difficult....... even when one has been working
with glazes for years. I wouldn't advise that you attempt it until you've
gained more understanding of how glazes are formulated. There are lots of
really good cone 6 glazes available that you can try to adjust to get the
surface you want. Colorants ususually behave the same at both temperatures.
If you really are set on developing glaze formulas of your own I'd suggest a
good calculation program. I use INSIGHT for the Mac. I'm no chemist and math
is not my strong suit..... but this program has been very helpful in
adjusting glazes to reduce problems.
If you can wait till late-Dec I'd be willing to run that glaze through the
program to give you a cone 6 starting point for experimentation.
Kathi LeSueur
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