Lili Krakowski on sun 9 sep 07
Someone wrote, a few days back, about a problem with white slip peeling off
a bisque pot. And added that slip cannot be put on bisque....Not so. There
ARE recipes for slip to go on bisque--I know there are some in Rhodes's
"Clay and Glazes for the Potter".
As to Seafoam!
I have no idea what "Seafoam" is as a color. And am sure a lot of other
people don't either. My guess would be light greenish-blue and that I
would look to copper, titanium, a pinch of cobalt....
As to ZINC in the glaze name. Glazes change names all the time, and change
content as well. "Mitzi's Barium Blue" --an IMAGINARY glaze here--was
created by Mitzi 60 years ago. It contained a lead frit, Colemanite,
Buckingham Spar, Barium, antimony--rutile and tin. Xavier took the lead
out of the glaze a few years later, and replaced the Colemanite with a frit.
Also took out antimony.
To his admiring students it became "Xavier's Barium Blue." A few more
years and Kim wisely replaced Barium with Strontium,and as Buckingham was
gone, Custer was used. Kim's adoring students speak of "Kim's Strontium
Blue." So now the glaze contains a currently available potash spar, a boron
containing frit, Strontium, titanium and tin.. Unless of course, Kim
decided to trade the tin for zirconium.
As you see, glazes change names and ingredients. Yes, this Seafoam may once
had had zinc in it...but not in the present incarnation it appears.
Starting in the other corner-- how would I get to a seafoam, assuming my
guess of what the color is is correct?
What do I know? That I want stuff in my glaze that benefits blue greens
(THAT was a stroke of genius!) So I think boron, I think zinc.
Here is a tiny starting point: Conrad's colemanite 5-6
Epk 44
Colemanite 28
Wollastonite 20
Custer 8
It is as you noticed a high calcium glaze. And according to RonJohn's
parameters COE is a bit low. Besides which where do I get Colemanite? But
it gives an idea.
Mott White is interesting:
Custer 49.4
Whiting 17.9
OM4 Ball Clay 14.4
Zinc 8.2
Titanium 4.7
Oddly enough this glaze crazes, although it has .336 Al203 and 2.149
SiO2--but we cannot go into that here.
"Nifty Pooh!" I cry, this being the battle cry of my people!
I take the whiting out of Mott and replace it with Strontium. Strontium
like Barium benefits turquoisy blues. Wollastonite is an anti-crazer in high
calcium glazes, so it stays. I use Frit 3124 or 3134 for my boron.I use
frit 3124 and or 3134 instead of Colemanite in the Conrad.
I do a straight line blend of the two. Just plain, just to see if I get
what I basically want: a fairly shiny, semi opaque, non crazing glaze.
When I have found one or two combos that please, I will experiment with
blends (both ends are the good results) with a little cobalt and one end,
and a little copper at the other....Or I could go with stains....NB: Read
the instructions on your stains! there is this little bitty number, leading
to a footnote which tells which ingredients benefit and which hurt color
results.In a week or so you will ahve what you want.
"And so, into the fog, into the night, goes Bulldog Drummond...."
What this whole megilah is about is that not only do glazes change names
over the year, but, as materials disappear or are removed from the pantry,
they change composition. Strontium replaces barium. Other fluxes replace
lead. To remedy crazing, wollastonite replaces whiting, dolomite magnesium
carbonate...and on and on. X works with a white body and find rutile give a
warmer look than titanium, but Y who works with an iron rich body sticks
with titanium.
Now please tell us: WHAT DOES SEAFOAM LOOK LIKE!
Lili Krakowski
Be of good courage
Tom at Hutchtel.net on sun 9 sep 07
That is a great run thought the sequence of how to think about developing a
glaze, Lili.
I'll try to find a piece of the seafoam that we had and post it. When it
worked right, you got swirls of the green-blue-green that you described.
Lay a bit of red into it, luscious. Unfortunately the best example we had
was a small plate (12") and it sold last weekend. I would guess the glaze
was what I've heard called immiscible glasses that the glaze forms because
the ingredients form 2 different glasses that won't mix. I intend to do
more work on this one day, and your discussion will be most helpful.
Tom Wirt
Hutchinson, MN
twirt@hutchtel.net
www.claycoyote.com
From: "Lili Krakowski"
>>Subject: About white slips; about glazes names
> As to Seafoam!
> I have no idea what "Seafoam" is as a color. And am sure a lot of other
> people don't either. My guess would be light greenish-blue and that I
> would look to copper, titanium, a pinch of cobalt....
>
> As to ZINC in the glaze name. Glazes change names all the time, and
> change
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