These Nitride Bonded Silicon Carbide shelves are rated to Cone 10 and are most suitable for Reduction firing in a gas kiln. Click here for important information concerning electric kilns and Oxidation firing. As with all refractories, ‘fast firing’ and ‘crash cooling’ are not advisable as heat shock can cause cracking. Click here for information on controlling heating rates.
For longest shelf life, we recommend you always 3-post your shelves. A 3-post configuration is the most stable support insuring even shelf weight distribution to eliminate “rocking” during firing. In addition, shelves should be “rotated” on a regular schedule. To properly rotate a shelf, it must be flipped and turned so that the kiln posts touch on the same positions but on the opposite side of the shelf. This will fully reverse firing stresses and warpage. Always place post over post when stacking a kiln for maximum stability and strength. Kiln washing shelves is advisable: see ‘Tips’ for more information.
Please note: there is no warranty on refractories! There are many factors that can cause shelves to fail over which we have no control. It is the nature of the material. Other than shipping damages, no claims can be made on refractories.
Kiln wash is used to protect shelves from glaze drips and contact sticking (when the unglazed “foot” of a pot fuses to the shelf during firing due to the degree of melt reached in the clay body itself). Commercial kiln washes often bond to the shelf surface and are difficult to remove making shelf rotation impractical. Do not use a silica-containing wash on NBSiC shelves. We recommend (2) possible alternatives:
1) Mix EPK and ALUMINA HYDRATE. Run a series of tests with a line blend as follows: 10% EPK to 90% ALUM., 20% to 80%, 30% to 70% etc.
The 10% EPK : 90% ALUM. mix, when applied as a thin wash, will wipe off with a damp sponge after firing. It prevents feet from sticking, but offers only a little protection against glaze drips. As you increase the EPK, the wash will better protect against glaze drips but will begin to stick to the shelf. Experiment to determine what formula best suits your needs.
2) Use “Setting Slabs” - clay slabs coated with kiln wash and placed under a glazed piece during firing. No kiln wash is applied directly to the shelf making rotation easy.
Packing and shipping charges apply to all shelf orders.
Smaller sizes and quantities may be able to ship via UPS. Larger orders/sizes must ship by common carrier freight.
For UPS shipments:
2-3 shelves per box, depending on the size. Maximum of 3 boxes total. $15.00 per box Packing . Shipping is additional- UPS rates apply. NOTE: shelves require significant amounts of packing and the boxes used are considered ‘oversize’ by UPS. Call (800) 431-6067 for a rate.
For Freight shipments:
A crating charge is assessed that is 10% of the dollar amount of the shelves with a minimum charge of $15.00 / maximum of $40.00. Freight charges are additional. Call 800-431-6067 for a rate.