Vince Pitelka on mon 9 jan 06
> I made three 6kg batches of terra sig this weekend: OM4, goldart, and
> redart. I followed Vince's proceedures using a homemade racking cane and
> hydrometer, so we can't expect too much.
Taylor -
I'm having a little trouble figuring out what you are asking. But first,
why did you use a homemade racking cane and hydrometer? A good racking cane
and hydrometer will cost you less than $20 for both. It only takes a very
small investment to get properly set up to make terra sig.
Second, have you tried the sig that you got? Have you concentrated it to
1.15 specific gravity to see how it works? It seems that you are assuming
that there is something wrong before you have a reason to.
But perhaps it would be best to try again. Raw clay is cheap. Get some
soda ash, and use the 0.25% (1/4 of 1%) of each this time. Don't let it
settle for "at least 20 hours." Let it settle for exactly 20 hours.
All I can say is that my method
(http://iweb.tntech.edu/wpitelka/professional/terra_sig.htm) works great if
you follow the instructions exactly. Use the deflocculants specified, in
the amount specified. Get a proper racking cane and hydrometer. When it
turns out well, terra sigillata is the ceramic elixir of the gods. Why not
just take the time and spend the small expense to do it right?
I certainly am not saying that my way is the only way, but I've tried a lot
of terra sig methods over the last two decades, and I spent a lot of time
trying to come up with the best method. It works great when you follow the
directions.
- Vince
Vince Pitelka
Appalachian Center for Craft, Tennessee Technological University
Smithville TN 37166, 615/597-6801 x111
vpitelka@dtccom.net, wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka/
http://www.tntech.edu/craftcenter/
Taylor, in Rockport TX on mon 9 jan 06
Howdy everyone:
I made three 6kg batches of terra sig this weekend: OM4, goldart, and
redart. I followed Vince's proceedures using a homemade racking cane and
hydrometer, so we can't expect too much.
Here is what I observed. Let me know where I went wrong.
I only had sodium silicate for a deflocc so I measured out .25% for each
batch. I didn't double it. I let the containers sit for over 20 hours.
When I went to siphon, I noticed that the OM4 container was the only one
with a noticable clear layer and that only about an inch deep (5 gal
buckets, opaque). The redart seemed the least settled, but no telling. I
stopped siphoning at the 2/3 level for the ball clay and as soon as the
sucking noise got lower in pitch with the two arts clays. I siphoned off
about twice as much volume of OM4 sig as I did the other two clays. I'm
guessing a little over a gallon for both gold and redart and about 2 and a
half galons for the OM4. I added aprox 3 and a half gallons to the initial
mixture.
Any thoughts. I can just as easily remix everything and have another go if
I need better deflocculation. Experts?
Taylor, in Rockport TX
Richard White on wed 11 jan 06
Taylor, you said you used only the sodium silicate to defloc, I presume
because you didn't have any soda ash? If your clay supplier is inconvenient
or out of stock, you can get the stuff at any swimming pool supply shop. We
use it to adjust the pH of our pool water, and it comes in small 1-2 lb.
tubs as well as huge barrels.
cheers,
dw
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