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The following chemicals are commonly used in glaze
preparations
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| ALUMINA HYDRATE is used for opacity, mattness, durability
and
hardness. It is the major source of alumina in glazes, and may also be used to protect
kiln furniture. ALUMINA OXIDE is responsible for the mattness or brilliance of glazes. It prevents devitrification, adds strength, and is insoluble in water. It melts at 3550 F. Use of too much alumina can cause a dry appearance. BARIUM CARBONATE is used as a high temperature flux, will produce satin matt glazes. TOXIC. BONE ASH is used as a flux in clay bodies, and will help in transparency. It is used as an opacifier in glazes.. Yes it is ground calcined animal bones - calcium phosphate. BORAX is a water soluble, low temperature flux which lowers the fusion point of glazes and promotes a smooth melt. Borax produces bright colors with various oxides, it is also a source of sodium and boric oxide in glazes. CHROME OXIDE GREEN This glaze pigment producing a variety of color, usually green, but red, brown, pink and white can be produced depending on the glaze formula, atmosphere and temperature of firing. It can affect adjacent ware above cone 6 C.M.C. POWDER is often used as a thickener, binder and suspending agent in slips and glazes. COBALT CARBONATE pigment produces blue colors, for glazes and slips. May produce purples when manganese is present and is best used for glazes due to fine particle size. COBALT OXIDE pigment produces blue colors, for glazes and slips and may have a speckled effect.. COPPER CARBONATE is a glaze and slip colorant producing a variety of greens, blues, and reds depending on the glaze formula , atmosphere and temperature of firing. COPPER OXIDE BLACK is a very concentrated colorant and flux. In an oxidizing atmosphere - greens result, in reduction, reds may occur and alkaline glazes produce turquoise blues. CORNWALL STONE (Cornish) is a type of spar used in clay bodies to give strength while firing. It is also used in engobes because of it's adhesive properties, with the addition of a suitable flux. Cornwall Stone can be used as a glaze. Sometimes called English Cornish Stone. DISPERSAL is a liquid deflocculant for porcelain slip and is also used as a suspending agent for glazes which are to be applied by spraying. (Darvan 7) DOLOMITE is useful as a source of calcium and magnesium. It can be used as a high temperature flux and to produce crystal formations. FLUORSPAR is a calcium compound used as a flux in glazes in small amounts. Decomposition during firing produces fluorine gas which may result in blistered glazes and TOXIC fumes. GERSTLEY BORATE is a sodium-calcium-borate compound used as a low temperature flux which helps prevent crazing. It can act somewhat as an opacifier No longer available GUM ARABIC is a powdered natural gum used as a binder and suspending agent in glazes. IRON CHROMATE produces dark colors in engobes and underglazes. It can also be added with manganese stains to clay bodies as a colorant. TOXIC in raw form and large quantities. IRON OXIDE RED is ferric oxide. It is basically the same as black iron oxide except not as concentrated. This is 99% natural and synthetic iron oxides. IRON OXIDE BLACK is ferrous oxide and produces various shades of brown or green when used as a glaze colorant or decorative oxide. In a high fire, matt glazes, iron oxide and titanium can produce reddish colors. LITHIUM CARBONATE is used as a flux in leadless glazes. It is a source of lithis, which is a strong high temperature flux. This will improve the brightness of glazes and increase the firing range. It will also reduces thermal expansion . |
MANGANESE DIOXIDE 325 is a black powder giving red, brown, purple, or black tones to clays and glazes. NICKEL CARBONATE is a green nickel producing browns, blues, grays and yellows in glazes. It can also tone down more intense colorants such as cobalt and copper. Maximum use is usually 3%. NYLON FIBER- Shredded fiber is added to clay bodies to increase working and dry strength, especially for thin or large scale slab work. PETALITE is a lithium feldspar used to decrease thermal shock. POTASSIUM CARBONATE is also known as Pearl Ash. This strong flux can be used to modify color in glazes. PYROPHYLITE is an aluminum silicate added to clay to reduce thermal expansion. RUTILE, CERAMIC GRADE is a titanium dioxide tan colorant, which contains a small amount of iron, and used for color. It has a tendency to provide various mottled textures. SODIUM SILICATE Liquid sodium silicate is used as a deflocculent in preparing slip. It reduces the amount of water needed and therefore reduces shrinkage. This is a pure sodium silicate and must be mixed to a 50/50 solution with water. SPODUMENE is a source of lithis, which is a flux that helps develop copper blues tones in glazes. It can replace feldspar and also reduces the vitrification temperature and shrinkage rate in glazes. SUPERPAX is the most popular zircon opacifier. It is used in a wide variety of applications. Superpax is effective in controlling texture, craze resistant and color stability in most glazes TIN OXIDE is an effective opacifier producing even, opaque, glossy glazes. The normal use of Tin Oxide in a glaze is between 5% and 10%, A dull matt glaze can result if used in excess. TITANIUM DIOXIDE is used primarily as an opacifier in glazes. Titanium Dioxide produces a matt surface, it is also used as a seeding agent in crystalline glazes. (Rutile is titanium dioxide with iron impurities) UMBER, BURNT is a hydrated ferric oxide with manganese dioxide. It is used for brush decoration to produce a reddish-brown and can also can be added to clay bodies to darken color. VEE-GUM T is a macaloid type gum suspension agent for glazes and can also used as a surface hardener. It is an extremely plastic, hydrous magnesium silicate used to give plasticity to non-plastic white ware and refractories. WHITING is also known as Calcium Carbonate. This is the most common source of calcium in glazes. It is a high temperature flux which give durability and hardness to glaze. WOLLASTONITE is a natural calcium silicate that reduces shrinkage in clays and glazes. It can replace silica and whiting. ZINC OXIDE is a high temperature flux that can increase the maturity range of glazes, and may also increase opacity. ZIRCOPAX This is the original zirconium opacifier and used mostly where semi-opaqueness is desired.
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