Terra Sigillata

Long story short, I needed a small amount of Terra Sigillata by way of alternative chemicals. Well after literally hours of research and no answers from any of the clay forums I created my own recipe for Terra Sigillata. I needed an alternative to sodium silicate as none is on hand and I’m impatient so I’d rather play kitchen chemist and see what I could come up with. It’s not rocket science. So I thought I’d share and save some folks from having to go out and find sodium silicate.

1 Parts Clay – I used a manganese wet clay (everything else calls for dry ball clay and I was not sure about using wet clay but it worked out fine)

3 Part Water

2 Teaspoons Jet Dry (for deflocculant)

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Jet-Dry and some old black clay with manganese as colorant
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Shake it up and you can see the separation clearly after an overnight sitting. The entire top was filled and I only got a picture after I had drained most of it. There was no layer of clear water on top. Entirely Terra Sigillata.
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Poke a hole in that mug! Just above the heavier solids.
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Drain into some kind of container
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I’m impatient so I boiled off the excess liquid by about 1/2
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1/2 cup morning piss (aka terra sigillata!)
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You can see a bone dry burnished piece with a few coats

Chemicals contained in Jet-Dry

Tetrasodium EDTA
Citric acid
Methylisothiazolinone    
FD&C Blue #1    
Water
Sodium Polyacrylate    
Methylchloroisothiazolinone    
Sodium cumenesulphonate

I think the Tetrasodium EDTA is the main source of deflocculant as it is used for a chelating agent and sequester and decrease the reactivity of metal ions that may be present in a product. DigitalFire lists Tetrasodium Pyrophosphate in their database of deflocculants, which is not the same as Tetrasodium EDTA but it seems to do the same thing.

The knife is a Kiridashi made from a recycled tool file by Jared Kramer Studios. The handiest knife I’ve ever known.

Interesting Article

A fantastic and interesting article I came across while researching simple glazes – http://www.ceramicstoday.com/articles/alternative_materials.htm

Not only do you get to learn some of the basics of creating glaze but you learn some interesting methods of sourcing the base materials. It still amazes me that thousands of years ago our forefathers discovered that burning clay and using copious amounts of wood ash would produce a primitive glaze. It was all over from there and we’ve been experimenting ever since.

Basic glazes are made up of clay, feldspar, silica, whiting, dolomite, talc, colorants, etc. And here we have an article going into the alternative materials. Our ancestors had to dig this stuff up from the ground. Now we can just go purchase from a ceramics supply store or experiment with “nonstandard” materials which can be purchased from the local hardware or drug store.

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Another nice site for recipes is here – http://glazerecipes.wikispaces.com/