McCoy, Jack Eugene on sun 27 dec 98
I noticed in a reply to another topic that calcined sea shells were used as
a glaze ingredient. Are they basically calcium? Or do they provide other
minerals as well?
Fay & Ralph Loewenthal on mon 28 dec 98
As far as I know calcined sea shells, was used as
soda ash, before we had the big manufacturers
making it artificially. I have used the calcined sea
shells in an ash glaze and it looked terrific. Hope
this helps Ralph in PE SA.
hal mc whinnie on mon 28 dec 98
the great japanese potter hamada collected shells on various beaches for
his glazes, this is probably how the traditioon came to the west. Bernard
Leach helped in the transportation.
hal
glazes history is a wonderfull new field, to trace the linneage of glazes
and glaze practices is a great challenge.
hal
garden of earthly delights
a public ceramic scultopure garden
kensington maryland
On Sun, 27 Dec 1998 23:54:49 EST "McCoy, Jack Eugene"
writes:
>----------------------------Original
>message----------------------------
>I noticed in a reply to another topic that calcined sea shells were
>used as
>a glaze ingredient. Are they basically calcium? Or do they provide
>other
>minerals as well?
>
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Jim Bozeman on tue 29 dec 98
I've been using calcined sea shells as a glaze ingredient for years. I
like it much better than whiting. I got the idea by talking with an
archeologist. Jim Bozeman
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david p george on wed 30 dec 98
I like the idea of using natural ingredients when possible. What kind of
shells are appropiate? How do you prepare them (eg clean? grind?
pulverize? etc)? What temp do you use to calcine?
dave with an endless supply of ugly clam shells, dreaming of beautiful
natural glazes.
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Veena Raghavan on wed 30 dec 98
Jim,
Could you please tell us to what temperature you calcine the
shells. You say that you use it instead of Whiting in your glazes. Would
the percentage be the same as Whiting and is the effect very different.
Thanks in advance for the information.
Happy New Year.
Veena Raghavan
75124.2520@compuserve.com
millie carpenter on wed 30 dec 98
Hi group,
is it safe to assume that sea shells can be calcined by simply putting
them in a piece of bisque and firing them with the next load of bisque
to ^ 04 and at that point the bowl will be full of sea shell ash, or
will it have melted into a blob at that point? and do I need to put a
lid on it to keep it from floating about? I have never calcined
anything before and don't want to create an avoidable mess. I create
enough mess as it is.
thanks
Millie in Md where 1 inch of snow paralyzes all but the 4 x 4 and sports
cars.
Eric Hansen on thu 31 dec 98
Millie:
Once I tried using seashells in place of wads? ok? I was firing low-temp wood, g
-Eric in Lawrence, Kansas
--
On Wed, 30 Dec 1998 09:36:45 millie carpenter wrote:
>----------------------------Original message----------------------------
>Hi group,
>
>is it safe to assume that sea shells can be calcined by simply putting
>them in a piece of bisque and firing them with the next load of bisque
>to ^ 04 and at that point the bowl will be full of sea shell ash, or
>will it have melted into a blob at that point? and do I need to put a
>lid on it to keep it from floating about? I have never calcined
>anything before and don't want to create an avoidable mess. I create
>enough mess as it is.
>
>thanks
>
>Millie in Md where 1 inch of snow paralyzes all but the 4 x 4 and sports
>cars.
>
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Fred Paget on sun 3 jan 99
millie,
As long as they are dry and free of mud inside you can calcine sea
shells in a cone 04 firing.
Sea shells are made of calcium carbonate and organic layers. If you fire
them what you get is a pile of quick lime - Calcium oxide. If quick lime is
left laying around exposed top the air for a few weeks it will air slake
and crumble into a powder of calcium hydroxide or common slaked lime.
There are a few interesting impurities that may be found such as
strontium, sodium, magnesium, etc.
You won't melt calcium oxide at cone 04. It takes a lot more heat to do
that, almost 4700 degrees F in fact.
A while ago I calcined an old conch shell to make some lime for making
hominy out of dry corn. A Clayart person who was knowledgeable warned me
that the lime was too impure to use in food, since it contains strontium.
Using lime instead of whiting (calcium carbonate) should need an
adjustment in the glaze formula to allow for the greater amount of calcium
in the lime. When you use whiting the carbonate burns to lime anyway but
you lose a molecule of CO2, so you need only 56 percent of the amount of
whiting to account for the loss (That is if you use newly fired quicklime.
Of course it will be picking up water from the air so that if it is old you
need more - fully slaked use 74 percent.)
Quicklime reacts with water releasing heat and can be nasty stuff.
Fred Paget
>----------------------------Original message----------------------------
>Hi group,
>
>is it safe to assume that sea shells can be calcined by simply putting
>them in a piece of bisque and firing them with the next load of bisque
>to ^ 04 and at that point the bowl will be full of sea shell ash, or
>will it have melted into a blob at that point? and do I need to put a
>lid on it to keep it from floating about? I have never calcined
>anything before and don't want to create an avoidable mess. I create
>enough mess as it is.
millie carpenter
-
From Fred Paget, in marvelous Marin County, California, USA
Bill Downs on tue 5 jan 99
Id like to put a little twist on this. I'm intrested in the chemical
composition of calcined coral. I expect its simular to the sea shells. I use
it for salt fuming so its been calcined in excess of 2300 f . It reacts to
moisture in the air just like the shells.I have lots but I haven't used it in
a glaze yet.
For the concerned inviromentalist I know the value of our reefs all the coral
burnt here is very dead and collected at the high water mark.
Until the trade winds return, Bill on the Big Island
where the volcanic haze (vog)is giving L.A. a serious run for its treasured
air quality reputation.
Louis Katz on wed 6 jan 99
Hi Bill,
The faster it reacts with water the less impurities it probably has. Quicklime
that has much magnesium in it slakes much slower than quicklime that is pure.
The level of heat also has an effect on this and higher temperatures slow the
reaction.
In any conversation about calcining shells, coral or limestone it is important
to mention that getting calcined limestone or other high calcium products in
your eyes is extremely dangerous. On contact with water quicklime releases heat
and is caustic a nasty combination.
Quicklime added to water can quickly raise the temperature of the water to
boiling, and I have seen wads dropped onto a wet floor pop and blow across the
room.
Bill Downs wrote:
> ----------------------------Original message----------------------------
> Id like to put a little twist on this. I'm intrested in the chemical
> composition of calcined coral. I expect its simular to the sea shells. I use
> it for salt fuming so its been calcined in excess of 2300 f . It reacts to
> moisture in the air just like the shells.I have lots but I haven't used it in
> a glaze yet.
> For the concerned inviromentalist I know the value of our reefs all the coral
> burnt here is very dead and collected at the high water mark.
>
> Until the trade winds return, Bill on the Big Island
> where the volcanic haze (vog)is giving L.A. a serious run for its treasured
> air quality reputation.
--
Louis Katz
lkatz@falcon.tamucc.edu
NCECA Director At Large
Texas A&M-CC Division of Visual and Performing Arts Webmaster (512) 994-5987
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