How To Test Fire A New Kiln

Buying a new kiln is an exciting investment and one of the most exciting aspects of this purchase is to undertake some test firing of your new kiln. Test firing is important to ensure that your kiln is firing accurately and that the firing process will work when you fire your pottery for real.

Here, we give a practical step by step guide on how to test fire a new kiln.

Step 1 - Preparing your kiln

The first thing to do when setting up your new kiln and before your first firing is to make sure any kiln furniture or kiln shelves you have bought for your kiln fit nicely into it and that all elements are suited to your machine.

Next, you should kiln wash your shelves. This can be achieved by adding kiln wash powder to water and mixing to an even consistency. You should apply two coats with a paintbrush. This will ensure that glazes don't stick to your shelf and over time, making them uneven.

Step 2 - Preparing your environment

Kilns can give off a lot of toxic fumes, depending on what you are firing and they can also give off a lot of heat. It's imperative therefore that your room is well ventilated. A proper ventilation system is recommended, which should power up when you power up your kiln so that you don't forget it.

Step 3 - Read your instructions!

If no instructions come with your kiln, then there are plenty of instruction videos online particularly for some of the main brands. There is often a quick start program guide but also the manual or video will advise you of a temperature and a time for each cone. Whether it is a manual kiln or an electric kiln, you'll find some useful information to help you.

Step 4 - Choosing your test cone

A cone is designed to show you whether your kiln has reached the correct temperature and whether your piece has been fired sufficiently. Cones range in how much heat they can withstand, so you should really do several test firings to see which works best for your wares.

You want to do your test firing at a relatively low fire temperature at a slow pace. A cone 06 is ideal for firing at a slow to medium speed and testing out your new kiln.

Step 5 - Getting ready to fire!

One of the best ways of assessing whether your kiln is reaching temperature the first time is to use a kiln sitter. This is essentially a box in which you can place the appropriate cone number inside. The cone is held in place by a bar and a moving rod.

Once the cone has reached the temperature required, it will bend and the rod will fall, automatically turning off the power to the machine with an electric kiln, but even with a manual kiln, observation can be made through the peep hole to see when this process has taken place.

Step 6 - Running your test fire

Once you have all your elements in place, load any test ware that you would like to trial, close your lid, use your controller to program in the settings for your desired time and temperature and go! As you can imagine, a kiln becomes extremely hot, so don't leave it unattended and don't open the lid during firing.

For a first time firing, you should choose a cone and program that lasts around 6-8 hours. If you haven't used a kiln sitter then your cone should be placed at least 2 inches away from the kiln wall. Once it has reached temperature, it will bend over enough to kiss the shelf.

Step 7 - Checking your wares

After firing is complete, a kiln will take around 8 hours to cool to room temperature. You should wait until it has completely cooled before opening your lid to check your finished products.

How do I test for other types of firing?

If you're looking to do bisque firing or glazed firing, you will need to test for different temperatures, so if you know that you are going to predominantly be using these techniques then make sure you experiment. Bisque firing requires the clay to be completely dry, as any moisture in the clay will cause it to explode and then the heat is slowly increased during firing. Glazed ceramics can vary -some look better when fired fast and some when fired slow. Again, this is why testing is so important.

Summary

When test firing a kiln, the most important aspect is preparation. If your kiln furniture or kiln shelves don't fit properly, you are likely to have issues. Equally, if you don't follow the instructions properly, or use the wrong cone for the wrong temperature, your results are likely to be poor. You also need to make sure that you are safe before engaging with a kiln. Don't touch it during firing unless absolutely necessary.

You shouldn't rush the process. Test, test and test again before you are truly comfortable with how your kiln works and what sort of temperatures you need for your chosen projects. At Soul Ceramics, we have a range of electric kilns which are easily programmable in order to make your first kiln firing much more straightforward. We're also on-hand to give you advice and support to ensure that your kiln is a success!