04 February 2018

Loading the Kiln

Loading a large kiln can often be intimidating. After talking with our friends at Paragon Kilns, here are answers to some of their most frequently asked questions...

Do you recommend 3 or 4 posts under a shelf? It is recommended to support shelves with three posts instead of four. Sometimes four posts can cause the shelves to wobble unless the bottom of the kiln is perfectly even, the shelves are flat, and the posts are exactly the same height. It is best to position posts fairly close to the kiln walls and away from the center of the kiln bottom. This places the weight of the kiln load close to the kiln stand and away from the unsupported kiln center.

How do you load the top shelf so that the ware fires to the correct temperature? On top-loading kilns, placing a shelf too close to the top of the firing chamber can lead to over- or under-firing. To help combat this, try using two half shelves, instead of a full shelf, stagger the height of the shelves. Another option is to mount the top shelf low enough so that element grooves show between the kiln lid and top shelf.

How does one prevent posts from sticking to the kiln shelves? When you unload a shelf out of the kiln after a firing, a post occasionally sticks to the shelf and then drops onto the shelf below. To help prevent this from happening, dip the ends of the posts about 1/8” – 1/4” in a mixture of kiln wash. Only a thin coat is needed.

How important is placement of posts inside a kiln? When possible, posts should line up vertically from one shelf to another throughout the kiln, especially with large kilns and heavy loads. Vertically aligned posts increase the stability of the load and reduce stress on the shelves.

Do you need to fire a top-loading ceramic kiln with an empty shelf in the top of the kiln? It is not required but, a shelf placed in the top of the kiln will prevent brick particles from falling onto glazed ware. This is also useful if the lid is cracked. Some people like to place a shelf in the top of the kiln to prevent the incoming air of a downdraft vent from affecting glazed ware.  Keep in mind, it would be better to fire the kiln without the blank top shelf, since the shelf uses up more electricity.

What kind of gloves can you wear to handle kiln shelves? You can find thin, leather-lined mechanic’s gloves at home improvement centers, or try batting gloves! They are both thin enough for you to load and remove shelves inside a kiln. They will also help to protect your hands against sharp bits of glaze or glass. Always wait until the shelves have cooled before removing them from the kiln.

Is it okay to continue using cracked kiln shelves? You should not fire cracked shelves. They could break during a firing and ruin a load of ware by causing other shelves to collapse.

Is there a way to repair a broken kiln shelf? Unfortunately, there is no way to repair a broken kiln shelf. However, all is not lost, as you can still use the shelf pieces. 
  • Use a tile saw to slice the shelf into horizontal sections. 
  • Place broken shelf pieces under pottery that is decorated with runny glazes or pieces that have too much glaze. 
  • If the bottom of your kiln is uneven, place the broken shelf pieces in the bottom of your kiln to support posts.
  • Use the shelf pieces as smaller shelves to place around tall pieces.
  • Silver clay and enameling: Place hot pieces onto the broken shelf. It is a good fireproof surface.
  • Lay the broken shelf across two half-shelves for even support of a piece with a large base.
Is it okay to fire freshly coated shelves with a glaze or bisque load? No problem! Just allow the shelves to dry before firing them.

What is the difference between loading ceramics in a front-loading kiln and a top-loading kiln? Smaller, lighter pieces are usually loaded in the front of the kiln near the door or on the bottom. This is because these are the cooler areas of the front-loading kiln. Load heavier pieces near the back wall of a front-loading kiln as that is where they will get more heat. The cooler areas of the top-loading kiln are usually the bottom and sometimes the top so, load lighter, smaller pieces in those areas.