Alice DeLisle on thu 30 jun 11
I have some material labeled "wollastonite" but when I used it to make a =
=3D
glaze, the glaze did not turn out right. It is very old and does not =3D
look like the new wollastonite that I bought. It is gray, not white, =3D
and has large, very hard lumps. When I drop it in water, the lumps =3D
collapse quickly and almost fizz as they hydrate. Is it possible that =3D
it really is wollastonite that has absorbed water from the air and needs =
=3D
to be calcined? If not, any idea how I can figure out what this stuff =3D
is that doesn't cost an arm and a leg? I have quite a bit - more than =3D
25 lb. Even disposal would be a problem with an unknown.
Thanks,
Alice DeLisle
wanderland@att.net
http://www.etsy.com/shop/IslandTextures
David Finkelnburg on fri 1 jul 11
Alice,
Lumps in wollastonite can be problematic in industry, also.
If I understand you correctly, you write that the hard lumps absorb
water rapidly when placed in water. Do the lumps soften when this happens?
A way to test might be to weigh a sample, say 100 grams, on your most
accurate scale, then calcine it on a raw clay or bisque tile or small
bowl to a low temperature (low enough so it does not form hard particles
which will not soften in water), say not more than 1,470F (800C), then weig=
h
the cooled sample again and see if there is any loss in weight. The loss i=
n
weight would be an indication that you are driving off water and how much.
Then take the calcined sample and put it into water and see whether you
still have hard lumps. If the calcining process takes care of the lumps
your problem is solved.
I do not know what the result of this test will be so I would like to
hear from you. Because of lump formation in wollastonite some ceramic
scientists refuse to use wollastonite as a glaze ingredient.
Good glazing!
Dave Finkelnburg
http://www.mattanddavesclays.com
On Thu, 30 Jun 2011 09:33:54 -0400, Alice DeLisle
wrote:
I have some material labeled "wollastonite" but when I used it to make a =
=3D
glaze, the glaze did not turn out right. It is very old and does not =3D
look like the new wollastonite that I bought. It is gray, not white, =3D
and has large, very hard lumps. When I drop it in water, the lumps =3D
collapse quickly and almost fizz as they hydrate.
Alice DeLisle on fri 1 jul 11
The lumps do soften and "dissolve" in the water. I know that =3D
wollastonite should not actually dissolve in water, but the lumps =3D
disappear almost immediately when put in water.
Alice DeLisle
wanderland@att.net
http://www.etsy.com/shop/IslandTextures
On Jul 1, 2011, at 5:23 PM, David Finkelnburg wrote:
> Alice,
> Lumps in wollastonite can be problematic in industry, also.
> If I understand you correctly, you write that the hard lumps =3D
absorb water rapidly when placed in water. Do the lumps soften when this =
=3D
happens?
> A way to test might be to weigh a sample, say 100 grams, on your =3D
most accurate scale, then calcine it on a raw clay or bisque tile or =3D
small bowl to a low temperature (low enough so it does not form hard =3D
particles which will not soften in water), say not more than 1,470F =3D
(800C), then weigh the cooled sample again and see if there is any loss =3D
in weight. The loss in weight would be an indication that you are =3D
driving off water and how much.
> Then take the calcined sample and put it into water and see =3D
whether you still have hard lumps. If the calcining process takes care =3D
of the lumps your problem is solved.=3D20
> I do not know what the result of this test will be so I would like =
=3D
to hear from you. Because of lump formation in wollastonite some ceramic =
=3D
scientists refuse to use wollastonite as a glaze ingredient.
> Good glazing!
> Dave Finkelnburg
> http://www.mattanddavesclays.com
> =3D20
> On Thu, 30 Jun 2011 09:33:54 -0400, Alice DeLisle =3D
wrote:
> I have some material labeled "wollastonite" but when I used it to make =
=3D
a =3D3D
> glaze, the glaze did not turn out right. It is very old and does not =3D
=3D3D
> look like the new wollastonite that I bought. It is gray, not white, =3D
=3D3D
> and has large, very hard lumps. When I drop it in water, the lumps =3D3D
> collapse quickly and almost fizz as they hydrate.=3D20
Alice DeLisle on sat 2 jul 11
Thanks, David. I will do as you suggest and let you know what happens.
Happy Independence Day (USA) and belated to Canada!
Alice DeLisle
wanderland@att.net
http://www.etsy.com/shop/IslandTextures
On Jul 1, 2011, at 8:55 PM, David Finkelnburg wrote:
> Alice,
> Thanks for your note! I think I understand. You are saying the =3D
lumps cease to be discrete big lumps and go back to being the very fine =3D
powder they were supposed to be. In that case I would consider the test =3D
I mentioned simply to know what the analysis of your wollastonite is. It =
=3D
is supposed to be no more than about 2% loss in weight on calcining. If =3D
it's significantly more than that you may not be getting as much calcium =
=3D
and silica in your glaze as the recipe calls for. With the test =3D
information you can adjust the recipe and skip calcining the whole 25 =3D
pounds. If you need help with any of this just let me know.
> Happy Fourth of July!
> Dave
>=3D20
> On Fri, Jul 1, 2011 at 6:12 PM, Alice DeLisle =3D
wrote:
> The lumps do soften and "dissolve" in the water. I know that =3D
wollastonite should not actually dissolve in water, but the lumps =3D
disappear almost immediately when put in water.
>=3D20
> Alice DeLisle
>=3D20
> wanderland@att.net
> http://www.etsy.com/shop/IslandTextures
>=3D20
>=3D20
> On Jul 1, 2011, at 5:23 PM, David Finkelnburg wrote:
>=3D20
>> Alice,
>> Lumps in wollastonite can be problematic in industry, also.
>> If I understand you correctly, you write that the hard lumps =3D
absorb water rapidly when placed in water. Do the lumps soften when this =
=3D
happens?
>> A way to test might be to weigh a sample, say 100 grams, on your =3D
most accurate scale, then calcine it on a raw clay or bisque tile or =3D
small bowl to a low temperature (low enough so it does not form hard =3D
particles which will not soften in water), say not more than 1,470F =3D
(800C), then weigh the cooled sample again and see if there is any loss =3D
in weight. The loss in weight would be an indication that you are =3D
driving off water and how much.
>> Then take the calcined sample and put it into water and see =3D
whether you still have hard lumps. If the calcining process takes care =3D
of the lumps your problem is solved.=3D20
>> I do not know what the result of this test will be so I would =3D
like to hear from you. Because of lump formation in wollastonite some =3D
ceramic scientists refuse to use wollastonite as a glaze ingredient.
>> Good glazing!
>> Dave Finkelnburg
>> http://www.mattanddavesclays.com
>> =3D20
>> On Thu, 30 Jun 2011 09:33:54 -0400, Alice DeLisle =3D
wrote:
>> I have some material labeled "wollastonite" but when I used it to =3D
make a =3D3D
>> glaze, the glaze did not turn out right. It is very old and does not =
=3D
=3D3D
>> look like the new wollastonite that I bought. It is gray, not white, =
=3D
=3D3D
>> and has large, very hard lumps. When I drop it in water, the lumps =3D3=
D=3D
>> collapse quickly and almost fizz as they hydrate.=3D20
>=3D20
>=3D20
Eleanora Eden on mon 11 jul 11
Hi David and Alice,
Some years ago I had this discussion with Jonathan Kaplan and did the calci=
ning tests.
For me there was a measurable but very small difference between before and =
after
calcining weights. I can look it up in my notebooks, but I know it was way=
less than 2%.
But the stuff did have lumps and so now I always dissolve the wallastonite =
in some of the
water separately before adding to the mix.
Best,
Eleanora
>Thanks, David. I will do as you suggest and let you know what happens.
>
>Happy Independence Day (USA) and belated to Canada!
>
>Alice DeLisle
>
>wanderland@att.net
>http://www.etsy.com/shop/IslandTextures
>
>
>On Jul 1, 2011, at 8:55 PM, David Finkelnburg wrote:
>
>> Alice,
>> Thanks for your note! I think I understand. You are saying the lump=
s cease to be discrete big lumps and go back to being the very fine powder =
they were supposed to be. In that case I would consider the test I mentione=
d simply to know what the analysis of your wollastonite is. It is supposed =
to be no more than about 2% loss in weight on calcining. If it's significan=
tly more than that you may not be getting as much calcium and silica in you=
r glaze as the recipe calls for. With the test information you can adjust t=
he recipe and skip calcining the whole 25 pounds. If you need help with an=
y of this just let me know.
>> Happy Fourth of July!
>> Dave
>>
>> On Fri, Jul 1, 2011 at 6:12 PM, Alice DeLisle wrote=
:
>> The lumps do soften and "dissolve" in the water. I know that wollastonit=
e should not actually dissolve in water, but the lumps disappear almost imm=
ediately when put in water.
>>
>> Alice DeLisle
>>
>> wanderland@att.net
>> http://www.etsy.com/shop/IslandTextures
>>
>>
>> On Jul 1, 2011, at 5:23 PM, David Finkelnburg wrote:
>>
>>> Alice,
>>> Lumps in wollastonite can be problematic in industry, also.
>>> If I understand you correctly, you write that the hard lumps absorb=
water rapidly when placed in water. Do the lumps soften when this happens?
>>> A way to test might be to weigh a sample, say 100 grams, on your mo=
st accurate scale, then calcine it on a raw clay or bisque tile or small bo=
wl to a low temperature (low enough so it does not form hard particles whic=
h will not soften in water), say not more than 1,470F (800C), then weigh th=
e cooled sample again and see if there is any loss in weight. The loss in =
weight would be an indication that you are driving off water and how much.
>>> Then take the calcined sample and put it into water and see whether=
you still have hard lumps. If the calcining process takes care of the lum=
ps your problem is solved.
>>> I do not know what the result of this test will be so I would like =
to hear from you. Because of lump formation in wollastonite some ceramic sc=
ientists refuse to use wollastonite as a glaze ingredient.
>>> Good glazing!
>>> Dave Finkelnburg
>>> http://www.mattanddavesclays.com
>>>
>>> On Thu, 30 Jun 2011 09:33:54 -0400, Alice DeLisle =
wrote:
>>> I have some material labeled "wollastonite" but when I used it to make =
a =3D
>>> glaze, the glaze did not turn out right. It is very old and does not =
=3D
>>> look like the new wollastonite that I bought. It is gray, not white, =
=3D
>>> and has large, very hard lumps. When I drop it in water, the lumps =3D
>>> collapse quickly and almost fizz as they hydrate.
>>
>>
--
Bellows Falls Vermont
www.eleanoraeden.com
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