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heloisa's questions/or, thoughts while watching a kiln

updated thu 11 may 06


Lili Krakowski on mon 8 may 06

FIRST: Thanks to ALL who on list/off list offered help with my kiln. I
followed through on everything, and learned a lot. A lot and a half. A
great deal. The two experts I thank most wrote off list, so I am
maintaining their privacy, but thanks, guys.

Then. What goes round comes round...or should.

So I spent the time watching my kiln fire (oh bliss! What a joyous sound
that hum is!) "dealing with" Heloisa's problems.

Please allow me a favorite joke. About 100 miles from NYC are the Catskill
Mountains famous for the Jewish hotels that "bred" a great many famous
comedians in the 1920s-1940s. That area also had a lot of chicken farms
that sold to the Kosher market. `One day a chicken farmer goes to see the
Rebbe. "Rebbe," he says, "my chicken are dying...." "Mmm," says the rabbi,
"Tell me. What do you feed them?" "Corn." "WRONG WRONG WRONG," says the
Rebbe. "Feed them millet." I will make this story short. For weeks the
man goes to see the Rebbe to report more deaths. For weeks the Rebbe offers
new suggestions. Finally the man comes in weeping. All the chicken have
died. Upon which the Rebbe explodes: "How DARE you run out of chicken, when
I have not run out of ideas?" Sounds familiar?

1. I always have believed in the Brazilian proverb: who does not own a dog
hunts with a cat. Or, in US lingo: dance with the one that brung you. I
spent some time calculating three -- glazes-- all calcium-borates--that
approximate very closely three published US glazes using 3134. Yes, I used
my GlazeMaster (TM) and it took no time at all. In Heloisa's situation, I
strongly feel the best way is to examine the composition of existing glazes,
then approximate with a new one with the same parameters.

One of the things I learned is that "often" about half Brazilian 093 and
half Brazilian 096 works wonders. In other words were I to start from total
scratch that is what I would start with.

1. Cream:

Br.Frit 096 26.2
Br.Frit 093 29
Whiting 11.1
ZnO 7.5
Kaolin 15.7
Flint 10.5

4% Ilmenite

If the Ilmenite is omitted this might work as a clear. Or you can try
opacifying with straight opacifiers--tin, zirconium, titanium.


Br. Frit 093 15.7
Br.Frit 096 62.9
Whiting 5.9
Kaolin 15.4

Either Or:

Br. Frit 093 25.6
Br. Frit 096 24.4
Whiting 18.2
Kaolin 27.7
Flint 9.1

Again: should work as clear, or, work opacified. Should do well with
colorants. Zinc in the "Cream" might affect chrome color.

Now then: I would test these, and do blends of them. Heloisa's clay has
fairly high shrinkage. That suggests ` crazing might not be a problem. If
it is, the usual cure is adding silica.

Please, Heloisa, don't talk about "books for dummies." NO one is a dummy
because she has not yet learned something! Dummies are people who don't
want to learn....

As to books...I am strong on Fraser's "Glazes for the Craft Potter". Very
good, very clear. But there are many excellent books.

As to your yellow pumpkin. Another glaze that contains some lithium, and
some boron, and some magnesium ought to work with that rutile/titanium
combo. Will look around...

Good luck.

Lili Krakowski

Ron Roy on wed 10 may 06

When subbing one frit for another - or a frit for GB -

Best to remember - if you increase the amount of frit in a glaze - you
increase the melting - if you increase it a lot you increase the melting a
lot so you have to expect running for instance.

If you decrease the frit your decrease the melting - so your glaze will not
be melting as much.

The key in this case is to find a frit with the boron as close as possible
to the original frit. If you can't do that you need to start adjusting the
alumina and silica (keeping the ratio the same) to compensate for more or
less melting.


>One of the things I learned is that "often" about half Brazilian 093 and
>half Brazilian 096 works wonders. In other words were I to start from total
>scratch that is what I would start with.
>1. Cream:
>Br.Frit 096 26.2
>Br.Frit 093 29
>Whiting 11.1
>ZnO 7.5
>Kaolin 15.7
>Flint 10.5
>4% Ilmenite
>If the Ilmenite is omitted this might work as a clear. Or you can try
>opacifying with straight opacifiers--tin, zirconium, titanium.
>Br. Frit 093 15.7
>Br.Frit 096 62.9
>Whiting 5.9
>Kaolin 15.4
>Either Or:
>Br. Frit 093 25.6
>Br. Frit 096 24.4
>Whiting 18.2
>Kaolin 27.7
>Flint 9.1

Ron Roy
15084 Little Lake Road
Brighton, Ontario
K0K 1H0

Heloisa Nunes on wed 10 may 06

I am taking the opportunity to thank all the generous people of clayart.
Without this forum and people sharing information, ceramics would be sooo
I am trying to pass along the information I get here to other people, and I
will try put post my results back.
Thank you Lilly, I will be of good corage. If I can't find neither dog nor a
cat, I will hunt with mice if I have to. You are an inspiration for that. I
love your web site and how wonderfully organized and graphic you are giving
the information on your tests.
Thank you for the recipes, and I look forward to trying them. I will stop my
posts for a week only because I am doing some small remodeling in my studio
(floors, sink and some paiting), and I will have to tend to that.
Next week I will be back with one more chapter of making glazes in Brazil. I
will get the information on materials(quartz, feldspars, talc, dolomite,
etc) tomorrow from a friend.
I do have Frit 3134 available, as well as lots of other american and
canadian goods, but they are imported and very expensive for use in large
quantities (e.g Frit 3134).

Cheers to you all from "wintery" São Paulo (15 oC, around 59oF)
Heloisa Nunes