How do I know which cone to fire to?

Deciding which cone to fire to while using electric kilns (at Groundworks Art Lab, we love SKUTT kilns for clay and glass) can be tricky. Between bisque firings, low-fire glaze firings, and oxidation firings, what’s right for you? If you’re curious about why and how to make cone packs, check out this info graphic and blog!

The order of cones by lowest - highest temp using our favorite, Orton cones:

Cone 022 1112°F (the lowest temp cone made by Orton; used for overglaze decorations, glass slumping, lusters, decals, enamels, and more!)

Cone 010 1648°F (the first cone to go down in reduction firings here)

Cone 06 1823°F (what we typically fire bisque to)

Cone 01 2043°F (the last cone of the front row on our cone packs for reduction firings)

Cone 4 2120°F (the first cone of the back row on our cone packs for reduction firings)

Cone 6 2228°F (a mid-range firing; we fire just past cone 6 for typical reduction firings and oxidation–our clay bodies are typically cone 6-10 and we love Rocky Mountain Clay)

Cone 10 2340°F (used for high fire clay, like our wood firings and porcelain!

Cone 12 2379°F (also used for high fire clay, sometimes our wood fires reach this temp)

Cone 20 2808°F (an even higher fire temp! sometimes stoneware and porcelain will be fired to this temp, but they would be specifically made for this and not within the typical range for firing)

Cone 30 2977°F (used for high duty stoneware and porcelain; far beyond the typical range for clay bodies)

Cone 42 3659°F (highest temp cone made by Orton; used for firing industrial products, think making refractory materials)

Bisque firings -

In clay, to bisque fire, cones 08, 06, and 04 are what we most commonly use (though you can fire to other cones, and I’ll get into that more, later). How does each cone function? 

Cone 08: Best for cone 10 porcelain, as it creates bisque with a higher porosity. In other words, for traditional Japanese porcelain glazing techniques, it’s perfect. It allows for (preferably lower SG glazes) to dry more quickly upon application. 08 is also safe for your regular bisqueware! It’ll feel and sound a bit different from cone 06 bisqueware, though (try it out for yourself and spot the differences!). 

Cone 06: Great for everyday use. It works for clay bodies that will be fired to any cone! This is what we most commonly fire our bisque to at Groundworks Art Lab. 

Cone 04: At Groundworks Art Lab, we fire our clear-glazed terracotta (and sometimes stoneware other clay bodies used for partner programs and youth classes) to cone 04. It’s also safe for a regular bisque firing, so everything can go into one kiln (although glazed work always goes on top)!

A good rule of thumb: lower cones will create more porous bisque (aka “soft” bisque) and higher cones will create a “harder” bisque that also burns off more impurities. You might have to do some extra careful sponging of your work before glazing when glazing “soft” bisqueware.

Glaze firings -

At Groundworks Art Lab, like many places, we typically fire to cone 6 for oxidation, and between cones 6 and 7 for reduction. If we are doing a specialty class, like our woodfire, soda, or porcelain class, we’ll fire to around cone 10 (though it can go past cone 10, and cone packs help monitor that). High fire reduction is the preference for many people, due to the pretty colors and finishes that can be achieved, though it can be quite costly (and not great for electric kilns). Check out how we adapted our glazes to look just as good at cone 6!

What about Raku?

For Raku, we fire to cone 04, just like our glazed terracotta! Though the Raku we do at Groundworks Art Lab is not traditional Raku, both are low fire processes! Fun fact, you can even do Raku in your microwave (though we don’t recommend doing it inside the house). If you’re curious, come check out our specialty class on Raku! 

Further information on the different cones you might fire to -

When looking at different underglazes, they’ll tell you what cones to fire to, and it can be confusing! Check out our guide on underglazes for some tips and tricks!