Calibrating your new kiln

My new kiln fires differently than my existing one(s).

Each kiln will be different in minor or major ways.  Suggested schedules are only starting points, even though they worked in your previous kiln. You need to learn about your new kiln’s characteristics in the same way you did with your first kiln. There are a number of ways to do this.

Many people recommend making test tiles for the different levels of fusing that you use and at different temperatures to determine which is the best for your new kiln.  Additionally, you need to note the rate(s) at which you fired these samples to make the test tiles accurate representations of firings.  Yes, these will be good references.  And yes, they are valuable if you have the time for all these firings.

 Idle Creativity

Observation during the firing of test tiles is the best and quickest way to discover how your new kiln is performing at various temperatures.  In one firing you can note the temperatures at which the various tack levels occur, and the contour and full fuse temperatures.  You can even take pictures through the peep hole of your kiln (as long as you don’t put the camera too close to the kiln!).  This procedure will make knowing your kiln much quicker and accurate than unobserved multiple firings.

To make use of the notes of the temperatures where the results were achieved in the test firing, back off 10°C (or 20°F) from the observed temperature and add 10 minutes processing time.  You may find after a few uses of these temperatures you may want to adjust the temperature a bit more, but you will have done the major experimental work in one firing.

It is a good idea to set up other test tiles and run the experiment again at a slower rate of advance.  This will give you information about how the different rates of advance affect the processing temperature and the look and texture of the piece, especially on the bottom.  The texture imparted at different processing temperatures becomes more important in slumping and draping processes.

In another firing you can set up various moulds and observe when the slumps or drapes are complete. Recording this information lets you know slump temperatures for various styles and spans of moulds.  Make sure you record the temperatures that the pieces slump fully into the mould. You can then back off 20°C from those points and add 30 minutes as a starting point for you actual slumping firings.

New kilns require experience to know what the appropriate temperatures are.  Buy setting up test tiles you can observe in one firing the various levels of fuse from tack to full fuse, so saving lots of firing time.

Further information is available in the ebook: Low Temperature Kiln Forming.