What is a Pyrometric Cone?

Pyrometric Cones are small ceramic bars or cones that are created to melt at various temperatures. Pyrometric Cones assure users that their firing process is under control.

Cones measure heat work (the effect of time and temperature). When you want to fire a kiln to a certain temperature, you use a specific cone that will melt near that temperature. The pyrometric cone is placed near a peep-hole where the potter can see the progress of its melting. Pyrometric cones give you visual assurance that your firing process is consistent day after day after day.

Often, a potter will use a series of three cones of increasing melting point in a row. In this way, the potter can see the progress from cone to cone of the heat work inside the kiln.

Pyrometric cones are labeled with numbers that correspond to their melting points. The number labels can be confusing because some have a leading zero (Cone 010) and some do not (Cone 10). The leading zero can be thought of like a decimal point. The melting point of pyrometric cones with a leading zero actually decreases as the number increases (Cone 011 has a melting point around 1607 degrees Fahrenheit and Cone 010 has a melting point around 1657). The melting point of pyrometric cones without a leading zero increases as the number increases (Cone 11 has a melting point around 2345 degrees Fahrenheit and Cone 10 has a melting point around 2345). The melting points for each pyrometric cone can be seen in the complete Orton Cone Chart below.

Pyrometric cones come in a variety of shapes and sizes. Bar pyrometric cones are created in a uniform straight shape. This is for consistent placement in kiln-sitters. Kiln-sitters are devices used inside kilns that hold bar pyrometric cones. When the cone melts, the kiln-sitter automatically shuts off the kiln.

Regular pyrometric cones cannot stand upright by themselves. They are made to be placed in a pack of clay or a cone plaque to be supported.

Self-Standing or Self-Supporting Pyrometric cones are coned shaped and have extra material at the bottom so that they can stand upright by themselves on a kiln shelf.

Orton is the largest manufacturer of pyrometric cones. As a result, they set the standard of the heat temperature that each cone represents. The melting point of each pyrometric cone is shown in the Orton Pyrometric Cone Chart Below.

Orton Pyrometric Cone Chart (Degrees Fahrenheit)

Orton Cone Chart Download the Orton Cone Chart PDF File

Cone Number

 Self Supporting Cones Normal Large Cones Small Cones
022 1087 Not Available 1166
021 1112 Not Available 1189
020 1159 Not Available 1231
019 1252 1249 1333
018 1319 1314 1386
017 1360 1357 1443
016 1422 1416 1517
015 1456 1450 1549
014 1485 1485 1598
013 1539 1539 1616
012 1582 1576 1652
011 1607 1603 1679
010 1657 1648 1686
09 1688 1683 1751
08 1728 1728 1801
07 1789 1783 1846
06 1828 1823 1873
05 1/2 1859 1854 1909
05 1888 1886 1944
04 1945 1940 2008
03 1987 1987 2068
02 2016 2014 2098
01 2046 2043 2152
1 2079 2077 2163
2 2088 2088 2174
3 2106 2106 2185
4 2124 2120 2208
5 2167 2163 2230
5 1/2 2197 2194 Not Available
6 2232 2228 2291
7 2262 2259 1307
8 2280 2277 2372
9 2300 2295 2403
10 2345 2340 2426
11 2361 2359 2437
12 2383 2379 2471
13 2428 2410 Not Available
14 2489 2530 Not Available