Getting to Know Cones: A Beginner’s Guide to Firing Pottery
In our first blog post, we talked about how important it is to fire your pottery at the right temperature for the clay you’re using. Today, we’re taking that idea a step further by exploring something called a “cone,” a term you’ll often hear in ceramics. Let’s break it down so it’s easy to understand!
What’s a Cone?
In ceramics, a “cone” is a small tool that looks like, you guessed it, a cone. It’s placed in the kiln when you’re firing pottery and is specially made to melt or bend at a certain temperature. Cones help you see if your pottery has absorbed the right amount of heat energy. Unlike a thermometer that just measures temperature, a cone actually responds to how hot the kiln is and for how long, giving potters a more accurate picture of what’s happening inside.
How Potters Use the Word “Cone”
Potters use “cone” in a few different ways, which can be a bit confusing at first. Here’s how you’ll usually hear it:
Describing Clay and Glaze
Potters often say things like, “This is a lovely cone 6 glaze,” or “I wish we had cone 10 porcelain.” This just means that particular clay or glaze is meant to be fired at a certain cone level. The cone number helps you know what temperature range works best for each type.Talking About the Physical Cones in the Kiln
These are the actual cone-shaped pieces you place in the kiln to melt at a certain temperature. They’re where the whole idea of “cones” in ceramics comes from.Explaining Temperature Ranges
Potters often use cones to describe different temperature levels, like cone 06 for low fire or cone 10 for high fire.
The Cone Number System
The cone numbering system can look a bit strange at first. The numbers run from low to high, with “0” cones (like 06, 04) representing lower heatwork (cooler temperatures), and numbers without a “0” (like cone 5 or cone 10) representing higher heatwork (hotter temperatures). Here’s a quick breakdown:
Lower cones: These are lower temperatures, often used for bisque firing (firing to harden the clay but not fully mature it) or for earthenware.
Higher cones: These are hotter temperatures, ideal for stoneware and porcelain, which need more heat to reach their final form.
Firing Ranges You’ll See in Studios
In most pottery studios, you’ll come across cones from 022 to 12. Choosing the right firing range for your clay and glaze is important. If you fire a piece too hot, it might warp or even melt. If it’s too cool, it’ll stay rough or porous and won’t be as strong. The chart below shows how they generally match up to the clays you use.
Firing temperature and cone infographic showing cone 022 to cone 14.
Why Cones Matter to Potters
Cones are important because they measure “heatwork,” or the combination of temperature and time. They bend or melt when your clay and glaze have absorbed the right amount of energy, meaning they’re ready. Using cones helps you know for sure when your pottery has matured properly, giving you more control over your results.
The Bottom Line
Cones might seem a bit complicated, but they’re actually a great tool to help you get the best results from your firings. They take the guesswork out of knowing whether your pottery has fired correctly, making it easier to create beautiful, durable pieces. So next time you’re in the studio, keep an eye on those little cones—they’re there to make sure your work reaches its full potential!
Happy firing, and may all your cones melt at just the right moment!