What is Seger cone test?

The Humble Seger Cone: Your Kiln’s Best Friend (Even in the Digital Age)

Okay, so you’re firing up a kiln. Whether you’re a seasoned ceramic artist or just starting out, you’re probably thinking about temperature, right? We’ve all been there, obsessing over pyrometers and digital readouts. But let me tell you about a little secret weapon that’s been around for over a century: the Seger cone.

These aren’t some fancy, high-tech gadget. Nope, they’re humble little pyramids made of clay, limestone, and a bunch of other stuff that melts at specific temperatures. Think of them as the OG temperature gauges, invented way back in the late 1800s by a clever German chemist named Hermann Seger.

So, how do these things actually work? Well, each cone is designed to soften and bend when it hits a certain temperature, kind of like a tiny, ceramic weathervane for heat. You pop a few of these cones into your kiln – usually a trio with slightly different melting points – and watch them through the spy hole. There’s usually a “guide” cone that gives you a heads-up, a “firing” cone that’s your target, and a “guard” cone just in case things get a little too toasty.

The magic happens when the “firing” cone bends over until its tip touches the base, forming a perfect 90-degree angle. That’s your cue! It means your pottery has gotten the right amount of “heatwork” – that perfect combination of temperature and time that transforms clay into something beautiful and durable.

Now, I know what you’re thinking: “Why bother with these old-fashioned cones when I’ve got a fancy digital kiln?” And that’s a fair question! But here’s the thing: Seger cones measure heatwork, not just temperature. That’s a crucial difference. Your pottery doesn’t care what the digital display says; it cares about how much heat it’s actually absorbed over time.

Plus, there’s something incredibly satisfying about visually seeing the progress of your firing. It’s a direct connection to the process, a way to understand what’s happening inside the kiln beyond the numbers on a screen. I’ve even used them to fine-tune my kiln sitter and firing schedules – they’re like a backup system, just in case the technology goes haywire. Trust me, it happens!

Reading the cones is an art in itself. A perfect bend means you nailed it. Not enough bend? Your kiln was running cool. Bent too far? Time to dial things back next time.

Of course, there are a few things to keep in mind. How quickly you heat the kiln, the atmosphere inside (especially if you’re doing reduction firing), and even how you position the cones can all affect how they bend. And yeah, there can be slight differences between cones from different manufacturers.

But at the end of the day, the Seger cone is more than just a temperature gauge. It’s a tool for understanding your kiln, connecting with the firing process, and ensuring that your pottery comes out just the way you envisioned. So, next time you’re loading up the kiln, give these little pyramids a try. You might be surprised at how much they can teach you. They’re the humble, reliable friends every potter needs.