Carole Fox on thu 28 mar 02
Well, I confess - I didn't make Vince's terra sigillata recipe and what =
I did this time didn't work! I tried a recipe from the archives =
attributed to Pete Pinnell called Real Lip Smacking Smooth Easy Terra =
Sig. I used OM4 ball clay. The recipe calls for 2-3 tbsp. of sodium =
silicate to 14 lbs of clay. I used two and a half tbsp. =20
What I have 20 hours later is just a bucket of thick slip. Do I need to =
start from scratch or should I add more of something and try again. =
Could the sodium silicate have been too concentrated? - it was old, =
thick, but not gelled.=20
many thanks in advance,
Carole Fox
Elkton, MD
cfox@dca.net
vince pitelka on thu 28 mar 02
Carole Fox wrote:
"What I have 20 hours later is just a bucket of thick slip. Do I need to
start from scratch or should I add more of something and try again. Could
the sodium silicate have been too concentrated? - it was old, thick, but not
gelled."
Carole -
Pete knows his stuff, but I don't believe in "easy" terra sig recipes.
Actually, mine is easy once you do it. Nothing complex in there at all.
You don't say how much water you were suppose to add. That is critical.
The sig must be the right consistency in order to separate, and if there is
not enough water, nothing happens. Also, the particle size in OM-4 is
already so fine, so there are no clear separation lines. When I make sig
from OM-4 I mix it to 1.2 specific gravity, let it settle for the 20 hours,
and then decant off the top two thirds as the sig. It works great.
If you can thin your batch to 1.2 specific gravity, you can settle it for
another 20 hours and then decant off the top two thirds, and you will
probably have a decent sig.
Good luck -
- Vince
Vince Pitelka
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Home - vpitelka@dtccom.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
http://www.craftcenter.tntech.edu/
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