Don't ignore the zeros in the cones!! There is a difference between cones 04, 05, 06 and cones 4, 5, 6 etc.

Think of cone numbers with a zero in front like negative numbers. The cone charts usually go from about cone 022 which is the coldest firing at about 1000 degrees F. Think of that zero as a negative number, so like "cone minus twenty two".

If a temperature is minus 22, that's pretty cold, right? That's how I remember it.

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Then the cone chart goes up in temperature to cone 01, which is warmer than 022. Cone 01 is around 2000 degrees F. So, remember that 022 is much colder than cone 01 (minus 22 is colder than minus 1, remember to read the 0 like it is a negative number).

The cone charts usually go up to cone 14 or so. Cone 14 is around 2500 degrees F. That is pretty darn hot, and many clays will start melting before then.

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When you fire:

Most potters do a bisque firing at around cone 06 or 04. That is a cooler temperature, around 1900 degrees F.

Then we do a glaze firing.

Glaze firing can be low fire, which is usually around cone 04, or midrange, which is around cone 5 or 6, or high fired, which is cone 8, cone 9, or cone 10.

Clays *vitrify* at different temperatures. Vitrification is when a clay turns rock-like. Most clays start to vitrify at around 1300 degrees F. Some clays will fully vitrify, some stay a bit porous, but when a clay is fired to the point that it is it's strongest for its purpose, we call it 'mature'.

Clays mature at different temperatures. A low-fire talc body matures at around cone 06 to 01. Terracottas tend to mature around 04, mid-range stonewares mature around cone 5 or cone 6, and bone china or high fired stonewares and porcelains mature at around cone 10.

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Some notes:

Some clays will melt at midrange or higher temperatures. Low fire earthenware clays will flatten at cone 5, and melt into goo at cone 8, and can ruin kilns.

High fire clays will work at low fire temps, though they may be chalky or may chip easily. Crank clay works well as a low-fired raku clay, but will also go up to cone 12 no problem.

If you bisque fire too hot, the clay is less porous, and won't hold the glaze on the pot, so it will be thin and may melt off when you do your glaze firing.

If you bisque too cool or too fast, the impurities in the clay don't burn out and you get more pinholes, bubbles, or bloating when you glaze fire.

If you fire a low fire glaze (rated for a cone that begins with a zero) at midrange (cone 4, 5, 6), or even hotter (cone 8,9,10), it will likely melt off the pot or bubble, or act weird. Some artists do this to get special effects, but it tends to leave sharp shards that will seriously cut you, and plays hell with your kiln shelves and can even melt onto the elements or kiln bricks necessitating costly repairs, so only do this if you have experience. Never do that if you are renting kiln space or using shared spaces. Only fuck up your own stuff, please.

Some kilns are only for low-fire. Their shelves, stilts, and posts will warp at high fire temperatures. When you buy a kiln, know it's rating. Some kiln shelves are only for low firing. They will warp at midrange and high fire temps.

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To Sum Up:

The zeros are important. Mentally treat the zeros in your cone numbers like they are negative numbers, and don't ignore them.

Here are photos of melted pottery I found from a google search and pulled from the donker studio blog (no links because of subreddit rules):

Beautiful, but costly.

https://preview.redd.it/um6981c2k2k91.png?width=1170&format=png&auto=webp&s=35575729636a583ff0fe14e6605ccefb7ceda0f0