Jamie Yocono on wed 1 aug 07
I have two glaze questions that I hope someone might answer, both about
glazing.
The first question is how one would go about making a speckled glaze. I used
to buy a Glazewerks glaze from ART in Wisconsin called Speckled Bone. It was
a lovely cream color, with specks in it, reminded me of vanilla ice cream
with a vanilla bean fleck. I'd love to be able to produce an effect like
that, but from the research and tests I've done, I'm obviously headed in the
wrong direction. Most of my experiments have been with manganese, and were
horribly muddy looking. I'm looking for something in the ^6 range.
Next question is about the glazes I am mixing, using recipes from M^6G. I've
developed some pretty nice color variations on the Waterfall Brown glaze,
and have even managed to eliminate most of the running. But even when I
apply the proper amount of glaze and it doesn't run, I am getting a very
thin amount of glaze on the rims of my pieces. It's so thin, it almost looks
clear on the rims. So I'm wondering if there's a way to correct this? I am
using a clear liner glaze inside, and 2 coats dipped on the outside. When
it's fired, the pieces (cups and small bowls) are very nice, with no drips
or thin spots.... but the rims are nearly bare. Any suggestions?
Thanks for your help!
Jamie in Vegas
Mert & Holly Kilpatrick on wed 1 aug 07
Jamie,
Try powdered ilmenite in a white or cream glaze, it will make specks. In a
white glaze the specks will be on the goldish tan side.
Here is a glaze using powdered ilmenite, which Ron Roy posted on Clayart
years ago, cone 6 oxidation:
Frit 3134 20
Custer feldspar 14
Wollastonite 14
Strontium carbonate 5
Talc 8
EPK 23
Flint 16
----------------
Zircopax 22
Ilmenite, Powdered 2
Holly
East Bangor, PA
Jamie wrote:
...I used
>to buy a Glazewerks glaze from ART in Wisconsin called Speckled Bone. It
>was
>a lovely cream color, with specks in it, reminded me of vanilla ice cream
>with a vanilla bean fleck. I'd love to be able to produce an effect like
>that...
Paul Lewing on wed 1 aug 07
On Jul 31, 2007, at 11:05 PM, Jamie Yocono wrote:
The first question is how one would go about making a speckled glaze.
Most of my experiments have been with manganese, and were
horribly muddy looking.
That's because you're using powdered manganese. If you use granular
manganese, it will remain as black/brown spots. There are also other
granular materials you can use that will make spots of various sizes
and colors. The most commonly used is illmenite, but granular rutile
is also available. Illmenite makes very dark spots, while the rutile
makes medium brown spots. There are also more esoteric things you
can use. I like Mt. St. Helens ash because the spots are not all the
same size and color, but that may be hard for you to get. Depending
on the glaze you're using and its composition, very fine beach sand
may work.
Good luck,
Paul Lewing
www.paullewingtile.com
Ben Shelton on wed 1 aug 07
as mentioned, granular materials will produce spotted effects while powdered
materials will disperse throughout the glaze and give a more even color.
I assume you will need particles in the 30~60 mesh size with the finer
particles removed.
Does anyone else have input on the particle size needed for speckling?
Ben
claystevslat on wed 1 aug 07
Jamie --
There may be some health issues with manganese (for the
potter), as well as the problem of muddying. I generally
try to avoid it. To get brown specks in a white or cream
glaze, I use RIO. 1 to 3 percent will do it for my needs
if I'm working with a buff or tan stoneware at ^6. (I start
to get different 'base' color effects at higher concentra-
tions.) At ^6 and in oxidation, the iron oxide particles
get suspended in the solidified glaze, giving the speckled
look. Note -- If you use a white clay body (stoneware or
porcelain) you will probably need to increase the RIO
concentration to 4 or 5 percent to get an interesting result.
If you're happy with your existing base glaze, this might
be worth a try. If you want a different base, you might
use this as a jumping-off point --
Recipe Name: Jill's Glossy Matte Mandy
Cone: 8 Color: White, brown specks
Firing: Oxidation Surface: Semimatte
Amount Ingredient
500 Nepheline Syenite
200 Silica
100 Whiting
300 Gerstley Borate--1999
100 Kaolin--EPK
100 Tin Oxide
11 Iron Oxide--Red
1311 Total
Unity Oxide
.286 Na2O
.076 K2O
.007 MgO
.631 CaO
1.000 Total
.528 Al2O3
.34 B2O3
.024 Fe2O3
3.136 SiO2
.001 TiO2
0 P2O5
5.9 Ratio
70.8 Exp
Comments: White with brown specks over most stoneware. More white
at lower temps, plain white over white stoneware or porcelain.
Crazes over more clays with a Gillespie Borate for Gerstley
substitution.
------------------------------------
Now as for the thinness at the lip question, remember how a
glaze firing works. The heat converts the glaze to an actual
glass, which is subject (as are we all) to gravity. It's
thick, but a thick fluid, it's not a solid. Think of honey
suspended on the edge of a knife -- with a long firing at
top range, naturally it'll get thin on the edge (in this case,
the lip).
I don't know how sensitive your glaze is to changes, but a little
increase in alumina goes a long ways towards thickening a glaze.
Try an increase of 1% of the glaze in molar equivalents AT MOST.
For alumina, that's quite a lot.
Another approach that might work would be to examine your firing
cycle and see if you can attain ^6 more rapidly, and hold at that
temperature for a shorter time (aim for less time with the honey at
room temperature on the knife blade, and more with it frozen on the
blade). You can still give the glaze time to develop colors and
depth with a slow fire-down, and it may be OK -- it will, however,
probably be different. Why? Because lots of the 'movement' in the
glaze comes from an extended period of glaze liquidity.
If it's not one thing, it's another.
I'd be interested to know your results and what you find that does
work.
Best wishes -- Steve Slatin
--- In clayart@yahoogroups.com, Jamie Yocono wrote:
>
> I have two glaze questions that I hope someone might answer, both
about
> glazing.
>
> The first question is how one would go about making a speckled
glaze. I used
> to buy a Glazewerks glaze from ART in Wisconsin called Speckled
Bone. It was
> a lovely cream color, with specks in it, reminded me of vanilla
ice cream
> with a vanilla bean fleck. I'd love to be able to produce an
effect like
> that, but from the research and tests I've done, I'm obviously
headed in the
> wrong direction. Most of my experiments have been with manganese,
and were
> horribly muddy looking. I'm looking for something in the ^6 range.
>
> Next question is about the glazes I am mixing, using recipes from
M^6G. I've
> developed some pretty nice color variations on the Waterfall Brown
glaze,
> and have even managed to eliminate most of the running. But even
when I
> apply the proper amount of glaze and it doesn't run, I am getting
a very
> thin amount of glaze on the rims of my pieces. It's so thin, it
almost looks
> clear on the rims. So I'm wondering if there's a way to correct
this? I am
> using a clear liner glaze inside, and 2 coats dipped on the
outside. When
> it's fired, the pieces (cups and small bowls) are very nice, with
no drips
> or thin spots.... but the rims are nearly bare. Any suggestions?
>
> Thanks for your help!
>
> Jamie in Vegas
Michael Wendt on wed 1 aug 07
We sell Mt St Helens Ash for $0.50/lb and can
ship it in the USPS flat rate boxes anywhere in
the USA for $8.95/box.
We also offer a scoria rock which is high
in iron and produces beautiful speckles at
cone 10 (may work lower too).
Regards,
Michael Wendt
Wendt Pottery
2729 Clearwater Ave
Lewiston, ID 83501
USA
208-746-3724
http://www.wendtpottery.com
wendtpot@lewiston.com
Taylor Hendrix on thu 2 aug 07
Oo Oo! My Eddy post just got me thinking. Has anybody tried taking the
dust from sharpening mower blades and placing it in a plain opaque
glaze for speckles? Worth a try.
Taylor, in Rockport TX
On 8/1/07, Jamie Yocono wrote:
...
> The first question is how one would go about making a speckled glaze. ...
Ron Roy on thu 2 aug 07
Hi Jamie,
I found that I had to model my rims to do what I wanted with each type of
glaze I used, A thin rim for Tenmoku to get it to break just right. If I
used that kind of rim for my celadon the glaze would wind up being too
thin.
Rims can be formed to hold glaze, to cast a shadow, - all kinds of reasons.
There can be as much thought in a rim as there is in a foot or a handle.
All you have to do is think about it.
RR
>Next question is about the glazes I am mixing, using recipes from M^6G. I've
>developed some pretty nice color variations on the Waterfall Brown glaze,
>and have even managed to eliminate most of the running. But even when I
>apply the proper amount of glaze and it doesn't run, I am getting a very
>thin amount of glaze on the rims of my pieces. It's so thin, it almost looks
>clear on the rims. So I'm wondering if there's a way to correct this? I am
>using a clear liner glaze inside, and 2 coats dipped on the outside. When
>it's fired, the pieces (cups and small bowls) are very nice, with no drips
>or thin spots.... but the rims are nearly bare. Any suggestions?
>
>Thanks for your help!
>
>Jamie in Vegas
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Ron Roy on thu 2 aug 07
Hi Holly,
Did you mean granular ilmanite? Do you use this glaze - does it melt ilmanite?
This looks like a stable glaze by the way - with a low enough expansion to
not craze on many cone 6 clays.
RR
>Jamie,
>Try powdered ilmenite in a white or cream glaze, it will make specks. In a
>white glaze the specks will be on the goldish tan side.
>
>Here is a glaze using powdered ilmenite, which Ron Roy posted on Clayart
>years ago, cone 6 oxidation:
>
>Frit 3134 20
>Custer feldspar 14
>Wollastonite 14
>Strontium carbonate 5
>Talc 8
>EPK 23
>Flint 16
>----------------
>Zircopax 22
>Ilmenite, Powdered 2
>
>Holly
>East Bangor, PA
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
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