Furnascote Nonvit

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Kiln Problems

Your kiln has to endure a hard life. It fires pottery turning it from a damp piece of clay to a crisp pot. Many hours of heating will be involved before the kiln is allowed to cool. Most kilns are constructed from fire bricks with or without a monolithic, castable or some other refractory lining.

Salt Glazing - The practice of salt and soda glazing produces vapours which are highly corrosive to kiln bricks and linings and which reduces the working life of the kiln. The vapours of these salts and glazing compositions condense on the kiln lining as well as on the pottery items, then drip down on to the items being fired. These "droppers" create rejects.

Thermal Shock - Irregular heating and cooling creates thermal shock which eventually causes the lining to crack and break down resulting in loss of heat and further physical disintegration of the firebricks. Disintegrating lining and bricks causes damage to all types of finishes and glazes resulting in rejects and the waste of valuable time and artistic effort.

Energy Loss - Damaged kilns will of course, allow heat to escape resulting in wasted energy and unreliable temperature control.

Furnascote NONVIT

Furnascote is a zircon containing refractory composition which is refractory to 1910°C. It is supplied as a powder which is mixed with approximately 10% by weight of water to make a cement or slurry as required. It may be used both in the construction of new kilns and to repair and maintain existing units. Furnascote is highly resistant to both thermal shock and to the corrosive effects of the various vapours and fumes generated in furnaces and kilns. It reduces slag adhesion, minimizes droppers and prolongs the life of existing fire bricks and linings. It is easy to apply.

Brick Variations - Furnascote may be used with most of the refractory brick types commonly used for kiln construction. Before coating soft, lightweight insulating bricks, we recommend that new bricks be fired to their service temperature for a few hours to allow any permanent shrinkage to develop. We also recommend a subsequent test-patch of Non Vit to confirm adhesion under normal kiln operating conditions prior to a complete application.

New Kilns - Furnascote can be used as the mortar to bind the fire bricks during the construction of a new kiln. Make a cement of Non Vit and fresh water, leave to stand for at least one hour prior to trowelling or brushing the cement between the bricks to a thickness of 1.2 to 2mm. Assemble the treated bricks to form your kiln. Leave for 3 to 4 days to dry out. See note on Brick Variations. Then wash coat the walls, roof and hearth facing the source of heat with approx 1mm Non Vit as a slurry. Leave overnight to dry before heating slowly to around 750°C to set the Non Vit, although the temperature above 500°C will be satisfactory at this stage. Roof arches should be of accurate construction so as to be under minimum stress when heated. Test-patch if unsure.

Existing Kilns - Scrape and clean any cracks or holes and fill them with a Furnascote cement and level off. Allow to dry for 2 to 3 days. Abrade and clean all inside surfaces before applying Furnascote Non Vit to a thickness of 1 to 3mm depending on the degree of protection required. Leave to dry out for 1 to 3 days before firing as New Kilns above.

Coverage - Approx 3kg per sq metre at 1mm thickness.

Packaging - Furnascote Non Vit is supplied in 25kg plastic drums.

Increasing the life of Burner Quarls