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Terra Sigillata Nirvana


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#1 Nelly

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Posted 30 September 2012 - 10:33 AM

Dear All,

A number of years ago I attended a workshop at Anderson Ranch. The instructor was Walter Ostrom. I hope it is okay to use his name openly in this forum.

He taught his majolica technique. It was there that I was introduced to terra sigillata.

I could not believe the shine and softness that it brought to a terracotta pot.

In those days we were still using Calgon and at that point in my life (without a studio) I was really just there for the experience. I did not take careful notes of all he said about how to create the terra sigillata.

What I do recall is that he really did it is a very precise and exact manner. He used specific clay, a ball mill (we had to wait overnight for some type of grinding t take place), Calgon, some other ingredients and water.

When it was finally done we had a huge container where the class could simply come and dip the bases of their pots. It was magic. The shine and softness of the terra sigillatta was like I found a type of pottery nirvana!! It just finished off the pots sooo well.

Anyway, I saw a video a few weeks ago on You tube. It showed a very unscientific way of making terra sig.

Ingredients:

1. Large plastic pop bottle and an Eaxacto knife

2. Clay slop of the body you are using

3. Sodium silicate

Given that I had all three ingredients in my studio I decided to give it a whirl. I mixed some clay slop until it was very smooth (terra cotta clay base), added a tablespoon or so of sodium silicate and some water. I funneled this mess into a big coke bottle and left it undisturbed for 20 hours. At the end of 20 hours I took my high beam flash light and observed the layers. There was a definite demarcation that I could see in colors. Then with the exacto knife I cut into the bottle and released the middle layer carefully in order to preserve the sludge.

I placed this terra sig mixture close to the kiln last night and noticed that it reduced to a nice milk consistency. When it went on the terra cotta bone dry bowls I had prepared.

After a short period of watching the terrra sig absorb into the clay I stood back and said to myself-- I did it--just like Walter!!!

I was afraid to post the link to this You Tube but if I can, do let me know. For someone like me who is busy conducting experiments in my studio and has a general idea of this process it was a huge break through.

Yes, I could have got the special siphoning tube and used the right dry clay ingredients but I thought when I saw this video "what the heck" give it a try. And it worked--maybe not at the optimal level if done scientifically but it does give the shine and softness that I was looking for. I am guessing the more you do this process the more exact you will want to become in how it is processed.

Nelly

#2 Chris Campbell

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Posted 30 September 2012 - 11:19 AM

You can definitely post about anything Walter Ostrom has to say ... He is definitely one of the Masters of terra sig. and majolica. His knowledge of clay and clay history is vast and he is a most entertaining speaker. :D

There are many ways to make terra sig ... from hyper perfect to coke bottle settling ... like most everything else in pottery it all depends on what you want to do next.

Chris Campbell
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#3 Isculpt

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Posted 30 September 2012 - 12:41 PM

You can definitely post about anything Walter Ostrom has to say ... He is definitely one of the Masters of terra sig. and majolica. His knowledge of clay and clay history is vast and he is a most entertaining speaker. :D

There are many ways to make terra sig ... from hyper perfect to coke bottle settling ... like most everything else in pottery it all depends on what you want to do next.


Chris, I've been intimidated about making terra sig, and this slaphappy system sounds right up my alley. But your comment makes me curious; what do you mean "it all depends on what you want to do next"? What would be possible with an exact system that maybe wouldn't be possible with this system?

#4 Chris Campbell

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Posted 30 September 2012 - 01:08 PM

Terra sig is great to have around the studio so please do not be intimidated by the process of making it. If you do it once you will totally get over it ... It's really easy, it just sounds scary.
People use specific ball clay because it yields more of the finished product than say, fireclays ... If you are doing all the work you may as well get a high yield.
If you follow the directions and use a glass jug you will see layers appear. You will know instantly when to stop siphoning.
I've heard varying opinions on the necessity for perfect specific gravity and have to admit that I don't always have it bang on.

A well made terra sig produces beautiful results by brushing on only a very thin layer so it is easy to polish it. The perfect % of deflocculant means you don't have to worry about it fluxing. The proper consistency means it won't flake off the pot.

You don't have to follow the most intricate 87 step recipe ... there are a lot of mid ground ones that produce great results.

Chris Campbell
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#5 Marcia Selsor

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Posted 30 September 2012 - 01:32 PM

I am using terra sig I made without a scale. I am in France and limited to what I have in the guest studio.
At La Meridiana last June Pietro Madalena used the same pop bottle method putting 500 grams of ball clay into a liter of water
Actually a liter minus the space for the clay. I bought a kilo of ball clay and put half of the ball clay into the bottle.
I also traveled with some DArvon which I use for terra sig at home. I separated it the same way with the exacto knife hole into the bottle.
Iburnished Limoges porcelain and hope to do some smoke firing in an electric kiln with foil saggars. That will be next week.So far the burnishing is going well.
I have also used the Charlie Riggs method of making terra sig as well.His recipe is for 5 gallons of sig at a time. he siphons with a 1/4 " plastic tube. I used that system when I did a workshop in Maui.
other equipment is a scale and a bucket and a beer ...for while you wait.
marcia

#6 Nelly

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Posted 30 September 2012 - 02:29 PM

You can definitely post about anything Walter Ostrom has to say ... He is definitely one of the Masters of terra sig. and majolica. His knowledge of clay and clay history is vast and he is a most entertaining speaker. :D

There are many ways to make terra sig ... from hyper perfect to coke bottle settling ... like most everything else in pottery it all depends on what you want to do next.


Dear Chris,

Yes, you are right. Walter Ostrum is not only an artist but a buuuurilliant man. Knock your socks off smart! I was younger--not sure I realized I was in the presence of such a great teacher. I did leave the course though with a love for color. I covet the pieces I made in this course.

On another note, can I expect to see an almost oily hue to the terra sig? I looked at it this morning and said to myself now how in heaven's name is this different from my throwing water except it is thinner. I wanted some observable proof I had the real McCoy. When I tried it on a pot it was the luster that told me that I did do it right but are there any specific things I should see regarding the appearance of the solution after the solution comes from the bottle? What I think I saw were as I said 1) only a slight oily surface appearance of the terra sig; 2) tiny bit of sediment in the bottom of the bowl and 3) a milk consistency.

Nelly

#7 Chris Campbell

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Posted 30 September 2012 - 04:51 PM

I have only made mine with OM4, Goldart and Redart and they always looked like hazy or reddish water ... No oily haze and not as thick as milk. When brushed on to a rough surface, the clay immediately becomes silky smooth. Burnishes easily.

Chris Campbell
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#8 Nelly

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Posted 30 September 2012 - 06:33 PM

I have only made mine with OM4, Goldart and Redart and they always looked like hazy or reddish water ... No oily haze and not as thick as milk. When brushed on to a rough surface, the clay immediately becomes silky smooth. Burnishes easily.



Dear Chris,

It is hard to describe what I am seeing in the terra sig. It is as though I can see the water move or almost separate into a faint layer of oiliness. Just a faint oil-type slick. A shimmer. Mine is like skim milk. I have to make sure the brush is not dripping when applied. A little does go a long way. And with a linen towel it burnishes beautifully. It appears as though it also has good adhesion to the vessel without sanding. I know some sand but what I did was burnish the pot with a stone before I took it off the wheel after trimming. Thus, this is just the icing on the cake. I love the stuff. Corrects any little defects and provides a touch to your face softness. No raised grog or need for fine sanding the bottoms when you use this stuff. Terra sig. makes everything smooth. Like I said "nirvana."

Nelly

#9 cracked pot

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Posted 30 September 2012 - 09:03 PM

I learned to make it with red art or Newman's red clay in a workshop . Mine also has a sheen to it that almost looks oily. We were told to dip the pot in it three times. I use it on cone 6 pots for accent color. It loses it's silkiness but looks amazing.




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