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.

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