Kiln shelves-Types

[Mark C.]

Types of Kiln Shelves,

They really vary in material and cost and it all depends on your end temperature you plan on firing to as to which you use.

If you are firing to cone 11 say then many types of shelves will warp at that repeated temperature. If you are doing low fire to cone 08 you really do not need to spend as much on a high end shelve as most will never bend at this low cone temp.

Mullite shelves are the most cost effective at low temps

They come in various thickness and 5/8 is the standard

They are made in all shapes for all kilns

Low fire electric or gas use they will hold flat at cone 08 .

These are pretty tough but do soak up any running glazes so you need to grind out any glaze runs from them before firing

Use kiln wash to protect them-these often come with electric kilns sold as furniture kits along with stilts.

 

The next leap up is corelites-they are made with a hollow honeycomb interior

These can work well at cone 6 but I have seen they fail at cone 10-especially if they have say 10 layers of shelves stacked on top of them. The hollow core can crush and they will warp at repeated high fire temps. Still a good value

Many use them at cone 6

Also, made in many shapes for all kilns

Also, they soak up glaze runs and need same treatment as above shelves

Use kiln wash to protect them

 

The old standard was silicon carbide shelves which still are around

These hold flat at cone 10 for some time but will banana curve over repeated firings over the years. Mostly in rectangular shapes-the standard was 12x24 and they also come in ½ and 5/8 and ¾ thickness –the thicker the longer they stay flat.

These hold runny glaze but not as bad as previous types mentioned-chip runs and grind smooth again

These are pretty durable-more so than Mullite or corelites

Use wash to protect them-These are old school

The newer ones now are Nitrate bonded and you can read about them here

https://www.baileypottery.com/Blog/ArtMID/885/ArticleID/42/The-5-Types-of-Kiln-Shelves-You-Need-to-Know-About

 

 

Dry pressed High Alumina shelves-more warp resistant than corelites or Mullites

They come is most shapes and are heavy. 32#s for a 1 inch thick 12x24.

I used them for years like 35 of them in my car kiln-Mine where made in England and called English dry pressed alumina-great in salt kilns due to the high Alumina content.

Baily sells them now in the east and Tacoma art center in the west.

Not sure on cost as I ordered mine in mass quantities.

They need wash and will soak glaze but not near as much as above shelves

 

The newer high fire gold standard which is several decades old now is the Advancers shelves made in Nitrogen gas arc furnace at unbelievable temperatures

These have a glassy smooth surface that glaze cannot stick to and will remain flat forever no matter how hot you take them to.

These shelves do not need wash unless you fire Porcelain as it sticks lightly to them-so wash them lightly if using Porcelains

They make them is all sizes for all kilns. These are brittle and break if dropped and cannot get wet as they can explode if fired fast and wet. More care is needed and they cannot be exposed to thermal shocking so no quick cooling.

On sale at this time for $190 for a 12x24 -5/16th thickness #8lbs at kilnshelve.com

 

There are Chinese knock offs that are lower cost to these but will warp and are made with far less quality controls-I use some large ones to top of my salt kiln from fallout roof junk-they will warp and I consider them disposable in the long run-they will hold glaze so wash is a must. They are also brittle. They cost less than most shelves

 

Bailey came out last year with a German Made thermo-lite. These are exactly like the Advancers in my tests-very glassy surface that does not hold any glaze runs. Does not need wash unless using Porcelain-brittle like Advancers but never warping-about $190 for 12x 24 -5/16^th thick #8lbs These  also are great shelves for high fire use

 

 Kiln shelve.com also has cryston shelves which are grainier surface and will soak glaze to a degree and need to be washed-They hold flat I’m told and are about $165for a 12x24 -5/16 thick-I have yet to test them.

I’ll, add more later as I’m burnt out now.

[oldlady]

thanks, mark.  good information and very useful.

[Marcia Selsor]

Mark,

excellent run down of what is out there. I just got a couple of perforated mullite shelves for raku. They are hard to find but I like them for small raku kilns for circulation the heat.

Marcia

[postalpotter]

Thanks Mark C.

Glad you put this out there. Much useful info.

[Rae Reich]

Excellent rundown, Mark. This info would be good in our new Glossary.

[postalpotter]

Thanks again Mark I do appreciate your knowledge and your efforts.

[Rex Johnson]

Yeah good news, this should be a sticky.

Remember folks, there is also the cost on shipping.

My last quote from Kiln shelve.com for4  cryston shelves added a $15 foam charge and another $178 shipping.

[neilestrick]

Shelves, when purchased in any volume (like more than 2) will usually ship freight. UPS and FedEx will just break them. Freight is expensive compared to UPS/FedEx, and the shipper will usually add on a crating charge- it takes them a lot of time to pack up shelves so they can survive shipping. So whenever possible, either by in large volume, or pick them up locally.

[Mark C.]

Shipping shelves is costly. Buy them in bulk to lower costs .Good shelves cost big bucks and the shipping also costs a lot. Advancers are packed in 5 lots and foamed into place. My last orders where shipped UPS with zero issues.Before ordering talk to the seller about shipping costs and bulk amounts to find the best deal. Meaning it may cost about the same to ship two as it does to ship 5 shelves. You need to figure all this out upfront.All shelve shipping is covered by insurance from most sellers. At least Bailey and Smith Sharp did.

In the old days when I ordered say 30 dry pressed English high alumina shelves they all got shipped freight and where palletized from Tacoma Art center.