Powdered Materials

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Alumina Hydrate

Occasionally the preferred source of alumina in a glaze because it remains in suspension for a longer time.

Ball Clay

Highly plastic sedimentary clays used in bodies to improve workability and in glazes to introduce silica and alumina. It aids suspension and adhesion. It is quarried at Axedale in Victoria.

Barium Carbonate

BaCO3 (S6 Poison) A secondary flux in stoneware glazes, up to 10%, but most frequently used to produce a satin-matt surface, between 10-20%. Small quantities (.05-2%) are used in bodies to prevent scumming.

Bentonite

A highly plastic volcanic colloidal clay, used as a suspending agent in glazes (2-3%) but it must be added to the dry ingredients. When added to a clay body, it improves plasticity. It has a high shrinkage at stoneware temperatures. Also known as Fullers Earth in some glaze recipes.

Bone Ash

Bone Ash (Calcined) Ca3(PO4)2, Essential constituent of Bone China, imparting the characteristic translucency. Also used as a secondary flux in glazes giving a milky quality.

Borax

A very useful glaze ingredient having strong fluxing power, comparable to lead oxide or sodium oxide. It intensifies the effect of colouring oxides but in the presence of lime it may cause precipitation giving an opalescent milky-blue white colour. It is soluble in water and therefore normally used in the fritted form.

Calcined Alumina (100 Mesh)

When used as a direct source of alumina in glazes, alumina has the effect of increasing glaze viscosity and firing range and resistance to crystallization. The crawling tendency of glazes with high clay content is reduced by introducing alumina as part replacement for clay. A melting point of 2050C makes alumina useful in batt washes, etc.

Calcined Alumina (300 Mesh)

When used as a direct source of alumina in glazes, alumina has the effect of increasing glaze viscosity and firing range and resistance to crystallization. The crawling tendency of glazes with high clay content is reduced by introducing alumina as part replacement for clay. A melting point of 2050C makes alumina useful in batt washes, etc.

Carboxy Methyl Cellulose

CMC Powder

Used as a base for a brushing medium to impart green strength to brush work and glaze application. As a basic guide use at between 0.5 to 2% on water content. Add to warm water to dissolve and age before adding to a the mix.

Chrome Oxide

"A versatile and high firing pigment, dark green in the unfired state and generally producing an opaque green. In the presence of calcium it produces a grass green and with cobalt and magnesium, a blue-green. In high alkaline tin glazes it gives a deep pink (chrome tin) developing to purple if boron is present. At low temperatures (

Cobalt Carbonate

Cobalt carbonate is a fine grained material that gives more even distribution of colour than cobalt oxide. Produces an evenly textured blue glaze (1-3%) which is less intense than the oxide. Cobalt almost always produces blues, which may vary somewhat with glaze composition, high zinc glazes tending to give greenish blues (especially if titanium is present) and high magnesium glazes tending to produce lilac or pink hues. Cobalt is quite soluble in glazes, consequently it has little or no opacifying effect in the amounts normally used (rarely more than 1-2%). Cobalt is an active flux and it may be necessary to take this into account when using it in some glazes, as it may increase their fusibility quite considerably. Like other raw oxides (or carbonates) of copper, manganese and nickel, cobalt may cause blisters or bubbles in some glazes due to changing oxidation state during the firing cycle.

Cobalt Oxide

Cobalt oxide produces an evenly textured blue glaze (1-3%) which is more intense than the carbonate. Cobalt almost always produces blues, which may vary somewhat with glaze composition, high zinc glazes tending to give greenish blues (especially if titanium is present) and high magnesium glazes tending to produce lilac or pink hues. Cobalt is quite soluble in glazes, consequently it has little or no opacifying effect in the amounts normally used (rarely more than 1-2%). Cobalt is an active flux and it may be necessary to take this into account when using it in some glazes, as it may increase their fusibility quite considerably. Like other raw oxides (or carbonates) of copper, manganese and nickel, cobalt may cause blisters or bubbles in some glazes due to changing oxidation state during the firing cycle.

Copper Carbonate

Cobalt carbonate is a fine grained material that gives more even distribution of colour than cobalt oxide. Produces an evenly textured blue glaze (1-3%) which is less intense than the oxide. Cobalt almost always produces blues, which may vary somewhat with glaze composition, high zinc glazes tending to give greenish blues (especially if titanium is present) and high magnesium glazes tending to produce lilac or pink hues. Cobalt is quite soluble in glazes, consequently it has little or no opacifying effect in the amounts normally used (rarely more than 1-2%). Cobalt is an active flux and it may be necessary to take this into account when using it in some glazes, as it may increase their fusibility quite considerably. Like other raw oxides (or carbonates) of copper, manganese and nickel, cobalt may cause blisters or bubbles in some glazes due to changing oxidation state during the firing cycle.

Copper Oxide - Black

Copper gives green in most fritted glazes, the colour being darker and richer in lead bearing glazes. In alkaline type glazes, the colour tends to blue, as is also the case in emulsion opacified high boron glazes, sometimes called boron blues. Large amounts of copper in glazes, especially lead glazes, give metallic effects and even graphite-type matts. Copper is an active flux and it may increase glaze melt fluidity; it may also cause crazing, due to its thermal expansion. In certain glaze compositions, under controlled reducing conditions, copper compounds can produce the reduced reds of rouge flamb and sang-de-boeuf; however these are difficult to obtain reliably. Since beautiful reds can now be reliably made with cadmium-selenium glazes, there is no longer any necessity to produce the reduced copper reds.

Cornish Stone

1kg - Synthetic

This material is a blend of selected minerals (no fluorine) that have a chemical analysis very similar to that of the naturally occurring stone. Cornish stone is an alternative to, though not direct replacement of, feldspar as a high temperature flux, having slightly less fluxing power. It can be used as a secondary flux in low temperature glazes.

Crack Filler

Used to mend cracks in bisqueware. Just mix with water (not too much!) to a suitable consistency to gently push into the crack. Re bisc fire to cure then decorate and glaze if required. Fires to a maximum temperature of 1300C.

Crocus Martis - Iron Oxide Purple

Iron oxides generally give a wide range of honey yellow, brownish reds, browns and blacks and are extremely popular colouring pigments for glazes and bodies. 3-8% gives yellows with yellow ochre, browns with haematite, red-browns with red synthetic, greys with iron chromate and black with magnetite or ferrous oxide. Speckled effects can be obtained with crocus martis. Warm colours obtained in lead glazes and cooler ones in lead free and alkaline glazes especially. Mottled creams can be obtained in the presence of tin. The final colour obtained with iron oxide varies with the type of glaze, firing temperature and kiln atmosphere. Iron oxide is also an active flux in glazes and even in small amounts will make a glaze noticeably more fluid. Synthetic red is very fine and produces more even shades from honey to dark brown (2-10%).

Dolomite

A natural material which combines calcium and magnesium carbonates. Generally used as a flux in stoneware glazes although in combination with other fluxes it can be effective down to 1060C. Above 5% it begins to opacify and will eventually produce a matt glaze.

Egyptian Paste

1kg - White

The principle of a self-glazing clay was originally developed in ancient Egypt and is now available as Egyptian Paste. It is a self-glazing clay. You need only the powder plus stain or oxide (recipes available on our website), a few lengths of nichrome wire, an electric kiln and a little imagination to create a wide variety of beads, buttons, scarabs, charms and a wide assortment of jewellery. Quite simple to work with by adding enough water to the powder to make a paste. Pieces can be formed by rolling on a clean, non-absorbent surface or in the palm of your hand or by hand modelling. To allow for complete glazing, beads and buttons can be dried by being strung on a piece of nichrome wire (the glaze is in the paste and will come to the surface during drying). Fired to Cone 06, the colours are vivid and bright. Stains and oxides can be added for the desired colour effects.

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