Fired Arts & Crafts
Greenware Firing
Monday, 08 November 2010 13:47

Let's start with a load of low-fire greenware. We will be firing it to cone 04. Greenware items can be set directly on the shelves and the pieces can touch each other. However, it is best to leave room between objects. Do not stack items or nest inside each other. Doing this could cause things to be under fired. Pieces should be set flat and upright on the shelves to avoid warping. It is often recommended to place a shelf up off the bottom of the kiln with small posts. Kilns equipped with a vent on the bottom will require this shelf. (Consult your manual for full details.)

Always try to align your posts on each later of shelves in the same position. You may find it easiest to place the posts on your shelf first, and set the pieces around. Try grouping items of similar height on the same level. Generally, smaller objects will be best in the lower sections, and larger items for the top. Taller creations on bottom layers mean stacking posts higher and creating potential for a wobbly shelf.

After being sure your posts are about an inch higher than any of the items on the first level, add your second shelf. (Stack posts to create additional height it needed.) Continue to add as many layers as needed. Notice the three cones in the center of each shelf. We are firing to cone 04, so we can have an 04 cone in the center, 03 on the left, and an 05 on the right. Always use the 3-cone method so you will be able to tell if a section of the kiln is firing hotter or cooler. Cones can help alert you to any problem areas by how the cones bend during the firing process. If your cones always bend properly, and then suddenly one day they don't, it could be telling you an element is burned out, or a number of other things.

Kilns that are equipped with a kiln sitter will require the placement of a small cone inside the chamber and lifting of the weight on the outside. Some kiln sitters also have a backup timer, which will also need to be set. Avoid placing items too close to the kiln sitter tube inside the kiln. if items fall against the device, it could prevent the kiln from shutting off at the correct time. If you have an electronic kiln, you can skip this step.

Kilns can be loaded in a variety of ways depending on the size and shape of items you have to be fired. With this load, we had a very tall lap, which took up almost the entire height of the kiln. We decided to do two layers of ware on one side, and fill the other side with the tall creations. Without a tall object like this, we could have done full layers of smaller things. Every time you load a kiln, you will discover different ways to utilize the space. Notice breathing space around the thermocouple on the far left side of the picture. Never allow anything to come into contact with the thermocouple during the firing process.

Always place lids on items in the greenware firing like we have done with this lamp, to assure they will fit properly. Lids are only left on in the greenware firing. Never leave lids on in a glaze load or they will fuse together permanently.

You should be ready to close the lid and start your kiln. Make certain nothing protrudes past the top before closing the lid. Leaving room between the items and the lid are also recommended. Set your controls according to the instructions in your manual and get started firing.