Calculating Electric Kiln Firing Costs

How much does it cost to say "You're fired!"? Clay, pottery accessories, and kiln furniture aren't the only expenses you'll need to budget for when creating pottery or ceramic ware. There's also the cost of firing your electric kiln (or gas kiln) - and unlike pottery bats or pottery stools, firing doesn't come with a preset price tag. However, the variable cost of kiln firing can be calculated with just a few simple steps. Method #1 If you've not yet used your electric pottery kiln, you can still get a rough firing cost estimate using your electricity bill and your kiln's voltage and amperage ratings (these should be located on the side of your kiln's control box). Depending on its size, your kiln's amperage could be anywhere from 15 to 65 amps. Voltage should be much simpler. Most electric kilns are rated for 240 volts or 208 volts. To get the first number in your kiln firing cost equation, multiply amperage by voltage and then divide by 1,000. Call this number A.

The next number is how many hours the firing will take. The tricky part is that a kiln doesn't operate at full power during the entire firing. So if you're doing an eight-hour firing, you might want to times eight by .6 or .7 to account for the scaled power usage. Call this number B.

The final number, C, is the cost per kilowatt hour from your electricity bill. A times B times C = a rough estimate of your kiln firing cost.

Method #2

This method is a little more empirical than method one. Instead of guessing how much power (or natural gas, with gas kilns) your pottery kiln will use, check the electricity (or natural gas) meter before firing and again after firing. Subtracting the first number from the second number will tell you how many kilowatt hours are used by a particular type of firing. Multiply that number by your bill's cost per kilowatt hour, and that's about how much the firing cost.

Additional kiln costs

• Kiln elements (the heating wires inside electric kilns) will usually last for about 100 to 300 firings (or fewer) before failing; replacement kiln elements are then required
• Kiln shelves will eventually need to be replaced as they wear down from the heat
• Kiln wash, which is used to protect kiln shelves, can be made at home or purchased from a commercial supplier