Jackson Gray on fri 26 feb 10
Awhile back there was a thread about what to do about your sodium
silicate that was no longer liquid.
A couple of weeks ago I decided to make a batch of terra sigillata from
a simple recipe I found somewhere (maybe it was Clayart). It called for
sodium silicate OR soda ash. Since my sodium silicate had hardened, I
opted for the soda ash version.
I waited several days but could not see the expected layering to
happen. A thin layer of water appeared on the top, but no middle
layer. I figured I had nothing to lose, so I chipped out the prescribed
amount from my sodium silicate jar and put it in a pyrex jar and added a
bit of boiling water. I stirred for quite awhile and saw some progress
but eventually just set it aside and came back to it the next day -
finally dissolved. I added it to my terra sig batch, stirred it up,
covered it and left it alone for a few days. Today I see the layers.
So what I'm trying to say - that at least in my case, it still works
even if it has hardened. An interesting side note (IMHO) is the
container of sodium silicate shows no evidence of my chipping at it -
the mixture is a smooth, level surface again.
For what it is worth, here's the recipe:
5 cups dry clay
1 gal hot water
1.5 tsp sodium silicate or 2 tsp soda ash
My version has both, plus about a half cup more hot water.
Jackson Gray
www.jackpots-pottery.com
DANL. ROTBLATT on sat 27 feb 10
Jackson,
I'm also a sculptor, and sodiium sililcate is used as a binder for
sand in cores and molds. Cores made with sodium silicate should be
used fairly quickly as they will absorb water from the air and become
soft and fall apart. Molds will also dissolve in water (before being
subjected to heat). Your experience fits - it's nice to know that it
doesn't change it's chemical structure by crystalizing and
reconstituting with water. I am entertained by the fact that the
surface healed itself! Sodium silicate is strange stuff - also used
to preserve eggs and if you paint wood with it, the wood becomes
fireproof. You can actually hold a torch to the surface of the wood
and it won't burn! I've thought of using it to fireproof under the
eves of the house...
Daniel Rotblatt
www.RotblattSculpture.com
On Feb 26, 2010, at 5:00 PM, Jackson Gray wrote:
> Awhile back there was a thread about what to do about your sodium
> silicate that was no longer liquid.
>
> A couple of weeks ago I decided to make a batch of terra sigillata
> from
> a simple recipe I found somewhere (maybe it was Clayart). It
> called for
> sodium silicate OR soda ash. Since my sodium silicate had hardened, I
> opted for the soda ash version.
>
> I waited several days but could not see the expected layering to
> happen. A thin layer of water appeared on the top, but no middle
> layer. I figured I had nothing to lose, so I chipped out the
> prescribed
> amount from my sodium silicate jar and put it in a pyrex jar and
> added a
> bit of boiling water. I stirred for quite awhile and saw some
> progress
> but eventually just set it aside and came back to it the next day -
> finally dissolved. I added it to my terra sig batch, stirred it up,
> covered it and left it alone for a few days. Today I see the layers.
> So what I'm trying to say - that at least in my case, it still works
> even if it has hardened. An interesting side note (IMHO) is the
> container of sodium silicate shows no evidence of my chipping at it -
> the mixture is a smooth, level surface again.
>
> For what it is worth, here's the recipe:
>
> 5 cups dry clay
> 1 gal hot water
> 1.5 tsp sodium silicate or 2 tsp soda ash
>
> My version has both, plus about a half cup more hot water.
>
> Jackson Gray
> www.jackpots-pottery.com
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