Sodium Hydroxide

Alternate Names: caustic soda

Description: Deflocculant

Oxide	Analysis	Formula
Na2O	77.50%	1.00
LOI	22.50%	n/a
Oxide Weight		62.00
Formula Weight		80.00

Notes

Also called caustic soda. A powerful deflocculant in clay slurries and casting slips, it behaves in a manner similar to soda ash. It is thus not used commercially with typical clays that respond well to more common deflocculants. However, if one needs to deflocculate clays contain soluble salts (e.g. calcium sulphate), like local terra cottas, then this might be the only option. It just means that molds won't last as long. Where materials exhibit obvious soluble salts, it is best to also add barium carbonate to precipitate as much of them as possible. Sieving out as much contaminant as possible it also best.

Some people also use this for its chemistry to source Na₂O to the glaze (it does not form crystals like soda ash). During the firing NaOH picks up oxygen and becomes Na₂O.H₂O. Thus we can deem Na₂O.H₂O as entering the kiln (weighing 80) and exiting as Na₂O (weighing 62).

Related Information

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Typecodes	Additives for Ceramic Glazes Materials that are added to glazes to impart physical working properties and usually burn away during firing. In industry all glazes, inks and engobes have additives, they are considered essential to control of cohesion, adhesion, suspension, dry hardness, surface leveling, rheology, speed-of-drying, etc. Among potters, it is common for glazes to have zero additives.
Materials	Sodium Carbonate

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