Our Dry-Pressed High Alumina kiln shelves have been the standard for both electric and gas kilns for decades. Suitable for both oxidation and reduction firing, they are a ‘clay’ shelf similar to old-fashioned cordierite, but with a higher alumina content and a solid Cone 10 rating. These shelves are dry-pressed rather than slip cast which produces a much denser shelf with excellent warp-resistance. Economically priced and available in many sizes to accommodate both top and front-loading kilns.
*Please see the Tips/Safety tab below for important restrictions and usage information for High Alumina shelves.
Packing & Shipping Charges apply to all shelf orders. Please review this information before placing your... Read More
Our Dry-Pressed High Alumina kiln shelves have been the standard for both electric and gas kilns for decades. Suitable for both oxidation and reduction firing, they are a ‘clay’ shelf similar to old-fashioned cordierite, but with a higher alumina content and a solid Cone 10 rating. These shelves are dry-pressed rather than slip cast which produces a much denser shelf with excellent warp-resistance. Economically priced and available in many sizes to accommodate both top and front-loading kilns.
*Please see the Tips/Safety tab below for important restrictions and usage information for High Alumina shelves.
Do not fast fire or crash cool: rapid temperature changes may cause cracking.
Not for use in Raku.
Not for use in wood kilns. Wood ash attacks the shelf material causing delamination.
Not for use in soda kilns.
3-Post shelves only. 3-Posts provide the most stable support for the shelf. More than 3 posts will cause the shelf to rock and shift as it expands and contracts during firing. This creates stress that can crack the shelf.
Rotate shelves between firings.If firing to Cone 8-10 it is recommended that you ‘rotate’ your shelves. To properly rotate a shelf it must be turned over and placed so that the kiln posts touch the shelf in the same places that they did on the opposite side. This fully reverses the stresses in the shelf to maintain flatness.
Use kiln wash. This material is the most porous of all the shelves we carry and glaze will soak into an unprotected shelf. The commercial wash we carry(C-175-164) is suitable for High Alumina shelves but it does contain silica which causes it to adhere to the shelf. It can be difficult to remove if you are rotating your shelves. An alternative wash is a combination of Alumina Hydrate and EPK Kaolin The proportions vary depending on your preferences. Start with the following formula:
70% Alumina Hydrate
30% EPK Kaolin
Mix to your preferred consistency. Thicker wash will absorb more glaze drips while a thinner wash can be used to prevent the feet of vitreous clays from sticking to the shelf.
You can also adjust the proportions of Alumina Hydrate and EPK to better suit your needs:
The higher the % of EPK the better the glaze absorption will be, but the more the wash will adhere to the shelf. This type of wash will be more difficult to clean off in order to rotate the shelf.
The higher the % of Alumina Hydrate the less the wash will protect against glaze drips but it will still prevent vitreous clay from sticking. This type of wash is easier to clean off to rotate the shelf.
You will have to experiment to find the best combination for your application.
NOTE: There is no warranty on refractories. Other than shipping damages, no claims can be made.
