Categories

Materials Classification for the Grid Method

This list is to help you categorise your materials when using the grid method, particularly when using the Calculation Page or the Percentage Calculator. Materials that form part of the base glaze (providing part or all of flux, alumina, silica) are marked: (Base Glaze). If you need it, there is more explanation about categories at the bottom of this page.

Material Category
Albany slip Flux material (Base Glaze)
Alumina Alumina material (Base Glaze)
Alumina hydrate Alumina material (Base Glaze)
Amblygonite Flux material (Base Glaze)
Ball clay Alumina material (Base Glaze)
Barium Carbonate Flux material (Base Glaze)
Barium Sulphate Flux material (Base Glaze)
Basalt Flux material (Base Glaze)
Bauxite Alumina material (Base Glaze)
Bentonite Additive
Bone Ash Additive or Flux material? (Base Glaze?)
Borax Flux material (Base Glaze)
CaCO3 Flux material (Base Glaze)
Calcite Flux material (Base Glaze)
Calcium carbonate Flux material (Base Glaze)
Carboxy methyl cellulose (CMC) Additive
Chalk Flux material (Base Glaze)
China clay Alumina material (Base Glaze)
Chrome oxide Additive (colourant)
Clay Alumina material (Base Glaze)
CMC Additive
Cobalt oxide/carbonate Additive (colourant)
Colemanite Flux material (Base Glaze)
Copper oxide/carbonate Additive (colourant)
Cornwall stone Flux material (Base Glaze)
Diatomite Silica material (Base Glaze)
Diatomaceous earth Silica material (Base Glaze)
Dolomite Flux material (Base Glaze)
Epsom salts Additive (flocculant, glaze thickener)
Erbium oxide Additive (colourant)
Fe2O3 Additive (colourant)
Feldspar Flux material (Base Glaze)
Ferric/ferrous oxides Additive (colourant)
Fireclay Alumina material (Base Glaze)
Flint Silica material (Base Glaze)
Fluorspar Flux material (Base Glaze)
Frit Flux material (Base Glaze)
GerstleyBorate Flux material (Base Glaze)
Glaze Flux material (Base Glaze)
Granite Flux material (Base Glaze)
Ilmenite Additive (colourant)
Iron Oxide Additive (colourant)
K. Feldspar Flux material (Base Glaze)
Kaolin/Kaolinite Alumina material (Base Glaze)
Lead oxide Flux material (Base Glaze)
Lead silicate(s) Flux material (Base Glaze)
Lepidolite Flux material (Base Glaze)
Limestone Flux material (Base Glaze)
Lithium Carbonate Flux material (Base Glaze)
Magnesium Carbonate Flux material (Base Glaze)
Magnesium Carbonate (light) Flux material (Base Glaze)
Manganese oxide/carbonate Additive (colourant)
Na feldspar Flux material (Base Glaze)
Neodymium oxide Additive (colourant)
Nepheline Syenite Flux material (Base Glaze)
Nickel oxide Additive (colourant)
Ochre Additive (colourant)
Petalite Flux material (Base Glaze)
Potash feldspar Flux material (Base Glaze)
Potassium carbonate Flux material (Base Glaze)
Praseodymium oxide Additive (colourant)
Quartz Silica material (Base Glaze)
Red Iron Oxide (RIO) Additive (colourant)
Red ochre Additive (colourant)
Rutile Additive (opacifier, also colourant)
Salt Flux material (Base Glaze)
Silica Silica material (Base Glaze)
Silicon carbide Additive (reducing agent/bubbling agent)
SiO2 Silica material (Base Glaze)
Soda Feldspar Flux material (Base Glaze)
Sodium carbonate Flux material (Base Glaze)
Sodium chloride Flux material (Base Glaze)
Sodium silicate Additive
Spodumene Flux material (Base Glaze)
Strontium Carbonate Flux material (Base Glaze)
Talc Flux material (Base Glaze)
Tin oxide Additive (opacifier)
Titanium dioxide Additive (opacifier)
Uranium oxide Additive (colourant)
Vanadium oxide Additive (colourant)
Washing soda Flux material (Base Glaze)
Whiting Flux material (Base Glaze)
Wollastonite Flux material (Base Glaze)
Wood ash Flux material (Base Glaze)
Yellow ochre Additive (colourant)
Zinc Oxide Flux material (Base Glaze)
Zircon Additive (opacifier)
Zircon opacifier Additive (opacifier)
Zircon silicate Additive (opacifier)
Zirconium oxide Additive (opacifier)

Some Notes on Categories for the Grid Method

When using the Grid Method for designing a 35-glaze grid it is necessary to classify your glaze materials into several categories:

Four Categories

  1. Flux material
  2. Alumina material
  3. Silica material
    The first three make up the base glaze. Then any others can go into:
  4. Additives, which includes colourants, opacifiers, suspenders etc.

It is important to understand that the category is determined not necessarily by the main oxide ingredient, but by why we are using it. For example, feldspar contains more of silica than flux or alumina, but we call it a flux material, not a silica material or an alumina material. This is because we add feldspar to a glaze for the flux content, not as a source of silica or alumina.

So we can decide the category by asking the question: "Why am I adding this material to the glaze?"

  • If it is to increase the fluxes, it is a flux material, category 1 (see above).
  • If it is to increase alumina, it's an alumina material, category 2.
  • If it is for the purpose of increasing silica, it is a silica material, category 3.
  • If it is to provide a colourant, or opacifier etc., it is an additive, category 4... and so on.

Some materials are borderline cases, and here you have to decide.

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