Fail number 2, time to build different vessel with new clay. My kiln at cone 5 fires to cone 4 temp so logic says cone 6 should fire to cone 5 temp eh? Nope six on the dot. No worries though. I’ll make something even better 🙂
This clay, which I believe contains manganese, needs to not be over fired and needs a loooong bisque to burn off any gasses and other things that can cause bloating. Which I did. A 13 hour slow bisque to cone 05. But in the end it blistered anyways because of over firing.
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)
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.