What would cause an ADVANCER® shelf to crack during a firing?

The vast majority of failures with ADVANCER® shelves can be traced to uneven temperatures across the shelf (thermal gradients) causing thermal shock and shelf failure. This can occur on heat-up or on cool-down for a variety of reasons. Typical problem areas in kilns include the bottom layer of shelves in a car kiln, where the seal between car and kiln is not tight permitting cold air to rush in when the kiln is shut off, using posts that are too massive (see “Do I need special posts for use with ADVANCER shelves?”), direct flame impingement on shelves early in the firing, overly large sight ports permitting cold air to cool off shelf areas unevenly, shelves too close to damper areas causing uneven cool-down of shelves in close proximity to damper. If you have any concerns regarding the use of ADVANCER shelves in your kiln, please call to discuss your particular situation to make sure that ADVANCER is right for you!

Do you recommend ADVANCER® shelves for use in wood-fired kilns?

ADVANCER® shelves have been used successfully in many wood-fired kilns. However, they should not be used in areas where there will be direct flame impingement early in the firing, such as fire mouths and areas adjacent to checker walls in second chambers. In these areas a conventional, thicker silicon carbide is preferred due to their ability to better withstand thermal shock. Wadding on brick posts under ADVANCER shelves is also recommended to minimize surface contact areas with massive kiln furniture.

Can I use ADVANCER® shelves in a Raku kiln?

No. Direct flame impingement on ADVANCER® shelves early in a firing will usually cause thermal shock and lead to shelf failure. ADVANCER can withstand rapid heat-up and cool-down, but temperature across the shelf must be even, which is never the case in Raku kilns.

What about using ADVANCER® shelves in a soda kiln?

ADVANCER® is often used in soda kilns. Clean-up of soda drips from the surface of the shelf is a breeze since the low porosity of ADVANCER does not allow the soda glass to get much of a grip on the shelf. Spraying or dumping soda into the kiln firebox and having it naturally disperse throughout the kiln is the preferred method of introducing soda into the kiln. Soda can also be introduced in a dry form when combined with whiting, with good results. We do not recommend spraying liquid soda solutions directly onto ADVANCER® shelves through a port hole, since this practice may lower the temperature enough to the point of soda contact to cause a significant temperature gradient across the shelf leading to cracking, thermal shock and failure.