Shirley Samuelson on mon 14 aug 00
Hi, hoping for some info...
I'm trying to make terra sigillata the right way (this time) using
Vince Pitelka's method (thanks, Vince, for sharing so very much). A
dose of sodium silicate based on the weight of the dry clay is part
of the recommended deflocculant. The sodium silicate I am familiar
with and able to get is liquid. But I am really suspicious that
sodium silicate might also come in a dry form and that the dry form
is what is intended? I've checked catalogs but haven't found a dry
form. Is there such a thing, or is liquid the right ingredient and I
should expect it is meant to be weighed just as the water is?
I'd truly appreciate any comment before I throw all my good stuff in
a bucket and coddle it for most of a weekend. Thanks in advance for
any help.
Shirley Samuelson
tgschs10 on tue 15 aug 00
I have been making up LOTS of terra sig by ball milling goldart clay with
added mason stains. I ball mill for 20-24 hours; this may be an excessive
time to ball mill and I just picked the time out of the air. Works great and
shines very easily. I wanted to try the terra sig at cone 10 for body color
and don't shine the terra sig because the shine disappears at these
temperatures. I have about 20 different stains that I've tried; the colors
tend to be muted and very matt and in general I haven't been too satisfied.
I've started to use some terra sig test tiles under different glazes and do
have some interesting results; many do look nice under a clear glaze. My gas
kiln has been down for about 6 weeks and I've done about 200 test at cone 10
oxidation. I'm now thinking that I would like to add a little gerstley
borate directly to the sig for testing; I did dip some of the terra sig
tiles into soda ash with some interesting results. Again I find that I am
uncertain how much to add to my mixtures and am thinking in terms of mixing
up some gerstley, spodumene, soda ash at the same s.g. as the terra sig and
adding 30-40% volume equivalents.
Tom Sawyer
tgschs10@msn.com
Tom Sawyer
tgschs10@msn.com
Tom Buck on tue 15 aug 00
SS:
Chief maker of sodium silicate (is it still National Silicate
Corp?) makes a broad range of product, from anhydrous crystal through to
liquids, each with a different composition.
The formulas generally quoted vary from 1 mole Na2O to 3.75 moles
SiO2 and a Na2O content as high as 2 moles Na2O to 1 moles SiO2. and these
proportions will be dissolved in water (certain amounts).
The industry using a particular sodium silicate usually dictates
what it wants and NatSil obliges.
The liquid sold to potters is likely to be 1 mole Na2O to 1 mole
SiO2 in water. So you can safely use that to guide you in how much
waterglass liquid to use.
In making a terra sigillata, the level of sodium ion is not
critical; be in the ballpark and you should get the fine particle range
you seek.
good tests. bfn. peace. Tom B.
Tom Buck ) tel: 905-389-2339 (westend Lake Ontario,
province of Ontario, Canada). mailing address: 373 East 43rd Street,
Hamilton ON L8T 3E1 Canada
Smart on tue 15 aug 00
The sodium silicate used with ceramics (i=2Ee=2E to make casting slips) is
always liquid, but you can buy two different sorts of sodium silicate=2E The
difference is the density=2E
Currently you can find :
Sodium silicate with density 1=2E55=2E It contains 14% Na2O and 33% SiO2=2E
Sodium silicate with density 1=2E33=2E It contains 8% Na2O and 26% SiO2=2ETh=
is
quality is most current for pottery=2E Its low density gives a better diluti=
on
with clay and water and the making duration is more rapid=2E
If you use Sodium silicate d =3D 1=2E55, you must decrease the rate=2E
Others types of sodium silicate more concentrated and costly are not
recommended to make casting slips or other deflocculating action=2E
Cordialement, Smart
Smart=2EConseil
Le site Fran=E7ais d=E9di=E9 aux passionn=E9s de c=E9ramique
The French site dedicated to ceramics lovers
smart2000@wanadoo=2Efr
http://perso=2Ewanadoo=2Efr/smart2000/
----- Original Message -----
From: Shirley Samuelson
To:
Sent: Tuesday, August 15, 2000 4:26 AM
Subject: sodium silicate for terra sig: always liquid?
> Hi, hoping for some info=2E=2E=2E
>
> I'm trying to make terra sigillata the right way (this time) using
> Vince Pitelka's method (thanks, Vince, for sharing so very much)=2E A
> dose of sodium silicate based on the weight of the dry clay is part
> of the recommended deflocculant=2E The sodium silicate I am familiar
> with and able to get is liquid=2E But I am really suspicious that
> sodium silicate might also come in a dry form and that the dry form
> is what is intended? I've checked catalogs but haven't found a dry
> form=2E Is there such a thing, or is liquid the right ingredient and I
> should expect it is meant to be weighed just as the water is?
>
> I'd truly appreciate any comment before I throw all my good stuff in
> a bucket and coddle it for most of a weekend=2E Thanks in advance for
> any help=2E
>
> Shirley Samuelson
>
>
>
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Lori Leary on tue 15 aug 00
Hi Shirley,
The liquid Sodium Silicate is just fine. Weigh it as you would any
other ingredient. You will love Vince's recipe, it works beautifully.
Good Luck,
Lori L.
lleary@sccoast.net
Pawleys Island, SC
Shirley Samuelson wrote:
>
> Hi, hoping for some info...
>
> I'm trying to make terra sigillata the right way (this time) using
> Vince Pitelka's method (thanks, Vince, for sharing so very much). A
> dose of sodium silicate based on the weight of the dry clay is part
> of the recommended deflocculant. The sodium silicate I am familiar
> with and able to get is liquid. But I am really suspicious that
> sodium silicate might also come in a dry form and that the dry form
> is what is intended? I've checked catalogs but haven't found a dry
> form. Is there such a thing, or is liquid the right ingredient and I
> should expect it is meant to be weighed just as the water is?
>
> I'd truly appreciate any comment before I throw all my good stuff in
> a bucket and coddle it for most of a weekend. Thanks in advance for
> any help.
>
> Shirley Samuelson
>
>
>
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