KK-8 Kiln Furnace Liner Maintenance

KK-8 Kiln Furnace Liner Maintenance

KK-8 Liner MaintenanceThree products are supplied with the KK-8 for optimizing and extending the life of the kiln liner: Liner Restore, Armor Coat and Spill Stop. All three products must be kept from freezing, or they will become unstable and unusable.

Restored Kiln Sections

Liner Restore is an alumina silicate based viscous material that is designed for filling cracks and patching any damage to the liner. This material is best applied in layers and allowed to air dry between applications. Generally the layers should not be any thicker than approximately 1/8”, when repairing any spilled flux holes or liner cracks. This material is tough and stable when applied properly to the liner and helps to strengthen and armor the liner as well.

Armor Coat is a high alumina material with the consistency of thick paint and is applied over the top of the Liner Restore, after repairing the liner. The high alumina formulation of Armor Coat helps resist liner erosion from the heat generated in the kiln and helps to shield the liner from any borax flux dusting from the crucible and minor flux spills. This material is painted onto the liner in thin coats and allowed to air dry between applications.

Spill Stop is a water based colloidal silica solution that must be mixed with calcium phosphate (bone ash) to the consistency of a thick paste. Spill Stop is used when there has been spitting of flux from the crucible, or minor spills onto the liner of the kiln. As previously mentioned, borax flux will attack the silica that the kiln liner is comprised of. Spill Stop will neutralize it.

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After you have fired your kiln a few times and the liner has stabilized and tempered, it is recommended that you apply the products in the following manner. Assuming that there has been no crucible spitting or spilling of the flux onto the liner, Spill Stop does not need to be applied to the liner and you can proceed to the Liner Restore Step. If there has been, Spill Stop is first applied, to absorb the borax flux and stop the flux from attacking the liner any further, as follows:

Spill Stop: Using a small, clean glass container, pour approximately ¼ to ½ fluid ounces of Spill Stop liquid into it (a shot glass works great). Slowly add bone ash to the liquid in the shot glass, while stirring the contents, until you have a thick paste like mixture. Using a small, stiff paint brush, coat the area where the borax flux has been attacking the liner. You don’t need to fill the area completely – just coat it well, with the Spill Stop paste. When the material dries, in approximately 12 hours, the silica is absorbed by the liner and the bone ash will absorb the borax flux, which stops any further erosion of the liner during upcoming firings. When you’re done with the Spill Stop, the shot glass and brush can be cleaned up with tap water. This method can be used anytime you have any minor crucible spitting or spills.

Liner Restore Step: Apply Liner Restore to the interior of the kiln’s liner. Liner Restore is fairly thick and a paint brush is not suitable for its application. It is recommended that your wear a thin pair of Nitrile rubber gloves and apply Liner Restore to the liner with your index finger. Rub the material into the surface of the liner, so that it penetrates into the alumina silicate insulation and seals it. When patching cracks and/or holes, use a gentle but firm pressure to force the material into the crack or hole, until it fills the void.

Remember that it is best to apply Liner Restore in thin layers, not to exceed approximately 1/8” at a time. We recommend that you apply a thin sealer coat to the entire interior of the kiln, using a gentle but firm pressure, then allow the kiln liner to dry for 12 to 24 hours at room temperature. After the sealer coat of Liner Restore has dried, apply another layer of Liner Restore to the interior of the kiln liner, smoothing out any rough spots and completing the filling of any cracks or holes. If you apply any Liner Restore to the mating surfaces of the modular pieces, make sure that you only apply a thin coat so that the mating surfaces remain flat and only fill any cracks to where they are flush with the top of the mating surface.

Armor Coat Step: Once you have completed the Liner Restore application, the next step is to apply Armor Coat. Armor Coat is a high alumina material that helps to prevent erosion of the liner from minor flux spills and heat. Armor Coat is the consistency of thick paint and can be applied with a 1” paint brush. Armor Coat will begin to set up fairly fast when applying it, due to the high alumina content of the material. So, you want to move deliberately and quickly when applying it. If the area you are applying Armor Coat becomes tacky, move on to another area to prevent unnecessary build up. As previously recommended, two thin coats are better than one thick one. Armor Coat will scale and crack if applied too thickly. It needs to be absorbed by the Liner Restore, to be effective. Armor Coat can be applied to the mating surfaces of the modular pieces of the kiln. Just apply it thinly, so the surfaces remain flat, without any unnecessary buildup of Armor Coat.

All of the Liner Restore Products are water soluble. So, if you get any of the material on the outside of the kiln, it can be cleaned up with a damp rag. The materials clean up easier if uncured, when cleaning them off the stainless steel jacket. When applying any or all of the products, wear nitrile gloves. Always allow adequate time for the applied materials to cure, prior to putting the kiln back into use. 24 hours at room temperature is recommended.