INSTRUCTORS INSIGHT: Jeff Stellges

Saggar Kiln Insert Project

or, How to fire Saggar work without messing up your regular or raku gas kiln

Items needed:

Four 16 x 20 x 1/2 inch kiln shelves

One 16 x 16 x 1/2 inch kiln shelf

Four 3 x 3 inches Stainless steel corner brackets

16 Stainless steel nuts and bolts

16 Stainless steel washers

8 Soft firebricks 9 x 4.5 x 2.5 inches, k2300 or k2600

Masonry or diamond drill bit

Above is the finished Saggar Box. The idea is to build this box inside your raku kiln or other gas kiln. Once you fill it with all of the Saggar firing materials and your work, close the lid and fire the kiln to 04 or 05 (set the cones on the top of the box). Once you are done firing let it cool, remove the lid, your work and save the Saggar materials for next time, remove the box and your kiln is ready for its next regular firing with no damage to the kiln.

Here is the Saggar Box ready to load with Saggar materials: vermiculite, wood chips, mulch, charcoal, seaweed (I prefer it on the dryer side, but not brittle), coarse rock salt, copper sulfate, orange peels, banana peels, and anything else that you have read or heard about.

Start with a layer of vermiculite on the bottom to cushion your pots.

Here is the first kiln shelf to put in your kiln. This shelf is 16 x 20 inches, but you can size it smaller if you need to so it will fit in your kiln. If you stay to 16 inches wide then the brick pattern and sizes will stay the same. The other shelves and bricks go on top of this shelf.

Here are the other three kiln shelf pieces bolted together with 3 x 3 inch L brackets, nuts, bolts, and washers. All need to be made out of stainless steel – no substitutions – or it will fall apart.

The back shelf is 16 x 16 inches; the two side shelves are 16 x 20 inches.

Here is a close up of the stainless steel washer and nuts assembly; note the large washer to spread the load on the kiln shelf.

Here you can see the inside and outside L bracket details. Notice how far from the top edge that the brackets are, also the L bracket must go on the inside of the kiln shelf. This helps with keeping the box stable and tight.

Here is the first row of soft bricks,9 x 4.5 x 2.5 inches. Grade k2300 and up is fine. Use one whole and one cut brick. The cut brick must be sized to fit tight enough to push out the side shelf pieces to the edge of the bottom shelf. This will create enough tension to keep the bricks together without having to mud it or patch with clay.

Here is a shot of the inside showing the L brackets and the bricks pushing out the sides creating tension for the rest of the bricks.

Here is the completed box with all of the bricks in place, the top bricks will have to be cut to 2.5 inch height. You can load your work and Saggar materials as you go or all at once. Sometimes it is easier to load as you go since you do not have to reach over the bricks in front during loading. Once you are done loading all your work and Saggar materials, place a coil of soft clay across the top row of bricks, put the top shelf in place, and put the cones on top of the shelf.

I use a 04 or 05 large self-standing cone.

Here is what it will look like when you are done. If you have any gaps in the bricks don’t worry about it as long as your Saggar materials are not falling out, it will be fine. Don’t forget the cones on the top shelf. Good Luck.

And this is possible!  Both pieces are about 16 inches in height, fired in a Saggar Box.