Ed Bull on wed 8 nov 06
After a recent article in one of the mags, and a local demo,
we have had requests by our pottery community to use sodium silicate
while throwing to get a textured exterior to pots. Looks cool, but...
I always have concern when introducing new chemicals into our kilns.
We have a large open industrial bay with a roll-up garage door which is
opened for ventilation while firing kilns (have fans blowing also).
We also have under kiln vents, but lots of nasty vapors
(from wax, glaze stuff, LOI from clay bodies) gets into the room.
This bay is also where our glazing area is, so potters need to be there.
We try to have the kilns firing when it's unlikely anyone needs to glaze.
Downtime on kilns while we replace elements is also a concern.
The expense and time spent is also an issue, so I worry about
introducing anything which may impact element life.
Anyone have thoughts about the implications of sodium silicate
fired on pots in oxidation to cone 6?
Cheers, and thanks in advance
Ed Bull
creativeclaypottery.com
Eric Serritella on thu 9 nov 06
Hi Ed,
I wrote the recent article in Pottery Making Illustrated which included
using sodium silicate to texture pots. I do fire it cone 6 oxidation and
have not noticed any change in element life as a result. (I haven't formally
tracked it relative to this material, but I do track my firings and I
haven't noticed any change in lifespan since using this material.)
I do not know specifically about vapors related to this material. I've
handled it as you are already doing by treating all firings for potential
vapors and venting both with a kiln vent and also overall room ventilation.
Not a scientific answer, but hopefully somewhat helpful.
Eric
Muddy Paws Pottery
528 Sebring Road
Newfield, NY 14867
607.564.7810
www.muddypawspottery.com
----- Original Message -----
From: "Ed Bull"
To:
Sent: Wednesday, November 08, 2006 6:39 PM
Subject: Sodium Silicate in Cone 6 oxidation
> After a recent article in one of the mags, and a local demo,
> we have had requests by our pottery community to use sodium silicate
> while throwing to get a textured exterior to pots. Looks cool, but...
>
> I always have concern when introducing new chemicals into our kilns.
> We have a large open industrial bay with a roll-up garage door which is
> opened for ventilation while firing kilns (have fans blowing also).
> We also have under kiln vents, but lots of nasty vapors
> (from wax, glaze stuff, LOI from clay bodies) gets into the room.
> This bay is also where our glazing area is, so potters need to be there.
> We try to have the kilns firing when it's unlikely anyone needs to glaze.
>
> Downtime on kilns while we replace elements is also a concern.
> The expense and time spent is also an issue, so I worry about
> introducing anything which may impact element life.
>
> Anyone have thoughts about the implications of sodium silicate
> fired on pots in oxidation to cone 6?
>
> Cheers, and thanks in advance
> Ed Bull
> creativeclaypottery.com
>
>
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Ivor and Olive Lewis on fri 10 nov 06
Dear Ed Bull
The Sodium Silicate brushed onto pots will dry out as kiln temperature =
rises. It will eventually melt at around 1060 deg Celsius and begin to =
dissolve clay. I cannot find the temperature at which it would fume but =
I imagine in its free state it is relatively stable well above the =
regular ceramic firing range, unlike Sodium Chloride. Nor will it be =
wafting around your kiln as happens when people use Sodium Carbonate to =
achieve a glazed surface.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
Timothy Joko-Veltman on fri 10 nov 06
On 11/8/06, Ed Bull wrote:
> Anyone have thoughts about the implications of sodium silicate
> fired on pots in oxidation to cone 6?
Sodium silicate is Na2SiO3 ... that is to say, 2 parts flux, 1 part
silica, and 3 parts oxygen. Nothing nasty. Oxygen may leave, but
the sodium and silica are not likely to go very far.
Cheers,
Tim
Ivor and Olive Lewis on sat 11 nov 06
Dear Timothy Joko-Veltman,
If you dig a little deeper you may find that there are three differing =
sodium silicate compounds, each with its own defining melting point. It =
is possible that the commercial product is a mixture of all three.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
Timothy Joko-Veltman on sat 11 nov 06
On 11/11/06, Ivor and Olive Lewis wrote:
> Dear Timothy Joko-Veltman,
> If you dig a little deeper you may find that there are three differing sodium silicate compounds, each with its own defining melting point. It is possible that the commercial product is a mixture of all three.
Actually, there are more than three varieties. However, the only
difference is the ratio of Na:Si:O, and there is only one melting
temperature (that I have been able to find): 1088C (ie., cone 04-03).
Yes, my original answer was somewhat simplistic, but even should they
all have a different melting point, that doesn't mean they are
therefore going to go flying around the kiln. Sodium remains a flux,
and silica a glass-former; as you of course know, both are essential,
and commonly used for forming a glaze.
Cheers,
Tim
Btw, please call me Tim.
Ed Bull on sat 11 nov 06
Thanks Eric, Ivor and Tim...
It seems relatively benign and, unless I get some bad feedback,
I'll turn people loose to begin experimenting with it.
I did find a useful warning on the archives from Fredrick Paget
about the potential danger of letting it set up with
the clay in the pan if you don't take care of it immediately.
Ivor and others responded about adhesive properties of Sodium Silicate
and Dolita reiterated the need to clean up quickly.
I don't think I'd want it going down the drains so we'll make
sure people clean up well and use the big clay and water buckets
we use instead of the sinks here at our studio.
Thank you all for your info and quick responses.
Just trying to be cautious for all of us here,
Ed Bull
www.creativeclaypottery.com
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