Russel Fouts on sun 18 jan 04
At 20:20 18/01/2004, you wrote:
Both of the frits in the glaze, 3124 and 3195 have lots of boron in them
but it doesn't explain why only these four have the problem (and the Red
Brown has it less). The 10 other colors are fine. I mix all the colors with
3124 and glycerin to brush them. Even if I don't add the 3124, they still
do it.
I had a look on the Mason site for these stains and couldn't find anything
that could cause a problem. No boron in the stains. They all contain some
zinc but so do most of the other colors that don't have this problem.
It's weird, I thought it might be because these colors were more refractory
but even adding twice as much frit to the color didn't help.
Thanks for your help.
>Russel,
> Regarding the white spots, is it possible there is boron in the frits
>that spotted? Boron will boil, I think. I agree, the water thing is a red
>herring. You might see if boron is a common ingredient in the troublesome
>stains. I'd be interested to know.
> Good potting!
> Dave, wondering how you and Vince would look side by side throwing
>slabs.... :-)
Russel Fouts
Mes Potes & Mes Pots
Brussels, Belgium
Tel: +32 2 223 02 75
Mobile: +32 476 55 38 75
Http://www.mypots.com
Home of "The Potters Portal"
Over 2300 Pottery Related Links!
Updated frequently
My work can also be seen on:
The World Crafts Council International Site: http://www.wccwis.gr
The World Crafts Council Belgium Site: http://wcc-bf.org (English Pages)
EasyCraft: http://www.easycraft.org
"To announce that there must be no criticism of the president, or that
we are to stand by the president, right or wrong, is not only
unpatriotic and servile, but is morally treasonable to the American
public." --U.S. President (and Nobel Peace Prize winner) Theodore
Roosevelt.
Earl Krueger on sun 18 jan 04
Russel,
Just because I haven't seen anybody mention it yet,
could it be that you just have bad batches of color.
Perhaps they were not fully fused in the manufacture
and the snowflakes are really refractory substances
that won't melt unless you reach ^99.
Have you contacted the manufacturer about this yet?
Earl...
Bothell, WA, USA
Diana Pancioli on tue 20 jan 04
Perhaps someone has already said this:
We find that white spotting in maiolica
is caused by the base glaze being applied
too THICKLY and is bubbling up through
the colorant as white spots.
Diana
Wynne Wilbur on tue 20 jan 04
Hi Russell,
Just wanted to let you know that I get this white spotting with certain
stains too. I suppose it's careless of me and that I ought to seek the
reason, but I don't actually mind the spots. If I want an area that is flat,
solid color, I either use the commercial colors that Amaco makes (which
don't seem to do this), or one of the Mason stains that doesn't spot (I've
tested a large number of them). For me, it does seem to be a bit related to
the thickness of the stain application (not the glaze) - thicker sometimes
makes fewer spots - I often have the red/purple Mason stains break up like
that by the way. I'm curious about the whys so I'd be interested to see what
you find. Have you contacted the Mason stain people?
Wynne
--
Wynne Wilbur
Assistant Professor of Art
Truman State University
Kirksville, MO 63501
660 785-4435
Russel Fouts on wed 21 jan 04
Earl
>> Just because I haven't seen anybody mention it yet, could it be that
you just have bad batches of color. Perhaps they were not fully fused in
the manufacture and the snowflakes are really refractory substances that
won't melt unless you reach ^99. Have you contacted the manufacturer about
this yet? <<
Careful what you suggest, I got them from Carla!
It's an idea to consider but 3 of the 4 are from Mason and the Black is
from Engelhart. It's not likely or a pretty big coincidence.
Russel
Russel Fouts
Mes Potes & Mes Pots
Brussels, Belgium
Tel: +32 2 223 02 75
Mobile: +32 476 55 38 75
Http://www.mypots.com
Home of "The Potters Portal"
Over 2300 Pottery Related Links!
Updated frequently
My work can also be seen on:
The World Crafts Council International Site: http://www.wccwis.gr
The World Crafts Council Belgium Site: http://wcc-bf.org (English Pages)
EasyCraft: http://www.easycraft.org
"To announce that there must be no criticism of the president, or that
we are to stand by the president, right or wrong, is not only
unpatriotic and servile, but is morally treasonable to the American
public." --U.S. President (and Nobel Peace Prize winner) Theodore
Roosevelt.
Wynne Wilbur on thu 22 jan 04
> Date: Tue, 20 Jan 2004 22:04:11 -0500
> From: Diana Pancioli
> Subject: white spotting
>
> Perhaps someone has already said this:
>
> We find that white spotting in maiolica
> is caused by the base glaze being applied
> too THICKLY and is bubbling up through
> the colorant as white spots.
>
> Diana
From looking at Russel's samples, and hearing his description of when it
happens, I'm pretty sure this spotting is not caused by thick glaze. It is
specific to a few Mason stains. I would describe it more like the color is
breaking up, but it does look like a blizzard of white spots too (if it's
the same effect that I get with Mason stain colors like blackberry wine).
The spotting from thick glaze is a lot more distinct.
Wynne
--
Wynne Wilbur
Assistant Professor of Art
Truman State University
Kirksville, MO 63501
660 785-4435
Marcia Selsor on fri 23 jan 04
To add to the several opinions going on, I think there are several reasons:
1. the white spotting is charateristic of traditional majolica that I
have seen in Spain and elsewhere.
2. It can be caused by some gases still being emitted from the clay
body...try bisque firing a little hotter to rid the clay of impurities.
3. When mixing mason stains or any other stains to Gerstley borate OR a
frit, this may also occur..try adding the stains to a mix of the base
glaze without the tin. 3/4 to 1/4 as a starter/
Hope this helps,
Marcia
>
| |
|
