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Orton Cone Temperature Equivalents

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There are four different types of Orton cones and bars (Small cones, Bar cones, Large cones, and Self-supporting cones).

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Cones are essential monitoring for all kilns.

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What do the colors of Orton Cones and Bars mean?

Orton cones and Bars have 11 different colors. Knowing the colors can make it easier to tell at a glance which cone you have. Cones have their number stamped on the side and that is the most important thing to look at since there are colors shared by different cones. There are 10 different colors that span Large and Self Supporting as well as Small Cones and Bars. Cones and Bars from 05 to 3 are dark red because of the iron that they contain.

Here is a guide to Orton cones colors.

orton pyrometic cone colors chart

The Large and Self-supporting cones are used to measure temperature uniformity and/or if there was sufficient heatwork done to mature the ware. Cones indicate whether the ware received an adequate amount of heatwork to properly mature the clay or glaze. A properly fired cone will bend over with the tip of the cone almost touching the shelf. After firing a kiln, a simple glance at the cone can tell if the firing was successful.

The small and bar cones are mainly used in the kiln shut-off device called the Kilnsitter. This is a mechanical device that shuts off the kiln when the temperature inside is sufficient to cause the cone to deform under the weight of the Kilnsitter rod.

The only true measurement of heatwork is from a Large or Self-supporting cone placed on the shelf next to the ware.

CONE NUMBERS - Orton makes cones from cone 022 up to cone 42. Cone 022 is the lowest melting cone and requires the least amount of heat to deform or bend. During firing, a cone softens and melts as it is heated. Cones used on the kiln shelf bend due to the effects of gravity pulling the tip down. This bending indicates the cone and the ware have received a specific amount of heat. It typically takes 15 to 22 minutes for cones to bend fully once they start bending. Each higher cone number requires more heat to bend. A cone 01 needs less heat treatment than cone 1 and cone 020 needs less than 019.
It is important not to confuse the lower maturing cones and bars, whose numbers begin with an 0, with the higher cones and bars not containing this prefix.
Although cones do not actually measure temperature, cone bending behavior and temperature are related. Generally, the faster the firing, the higher the temperature required to bend the cone and the slower the firing, the lower the temperature required to bend the cone. The 6 oclock position (90 angular degrees) is considered the end point of cone bending.
Typical uses for cone numbers are as follows:

NUMBER: 022 TO 011 - Used in firing of overglaze decorations, lusters, enamels, and decals and for glass fusing, slumping, and decorating. The temperature equivalent range is approximately 1050 - 1550F (560 to 850C).

NUMBER: 010 TO 3 - Made as a regular series (red, iron-containing cones) and as an Iron Free series for use in reducing atmospheres. These cones are used in the firing of craft and art bodies, for wall tile, glazes, and some structural clay products. The temperature equivalent range is approximately 1600-2150F (890 to 1170C).

NUMBER: 4 TO 12 - Used in firing porcelain, floor tile, china, stoneware, structural clay products and some refractory materials. The temperature equivalent range is approximately 2175-2345F (1180 to 1340C).

NUMBER: 13 TO 42 - Used for firing industrial products up to 3659F (2015C).

Here Is The Orton Cone Temperature Chart: (Download Complete Orton Cone Wall Chart Here.)

Cone Equivalent Temperatures (F)
	Self Supporting Cones 1 3/4" mounting height						Large Cones				Small 15/16" Height
	Self Supporting Cones 1 3/4" mounting height						Large Cones				Small 15/16" Height
	Regular			Iron Free			Regular		Iron Free		Regular	PCE
	Heating Rate (F/hour)						Heating Rate (F/hour)
Cone	27	108	270	27	108	270	108	270	108	270	540	270
022	1049	1087	1094				N/A	N/A			1166
021	1076	1112	1143				N/A	N/A			1189
020	1125	1159	1180				N/A	N/A			1231
019	1213	1252	1283				1249	1279			1333
018	1267	1319	1353				1314	1350			1386
017	1301	1360	1405				1357	1402			1443
016	1368	1422	1465				1416	1461			1517
015	1382	1456	1504				1450	1501			1549
014	1395	1485	1540				1485	1537			1598
013	1485	1539	1582				1539	1578			1616
012	1549	1582	1620				1576	1616			1652
011	1575	1607	1641				1603	1638			1679
010	1636	1657	1679	1600	1627	1639	1648	1675	1623	1636	1686
09	1665	1688	1706	1650	1686	1702	1683	1702	1683	1699	1751
08	1692	1728	1753	1695	1735	1755	1728	1749	1733	1751	1801
07	1764	1789	1809	1747	1780	1800	1783	1805	1778	1796	1846
06	1798	1828	1855	1776	1816	1828	1823	1852	1816	1825	1873
05½	1839	1859	1877	1814	1854	1870	1854	1873	1852	1868	1909
05	1870	1888	1911	1855	1899	1915	1886	1915	1890	1911	1944
04	1915	1945	1971	1909	1942	1956	1940	1958	1940	1953	2008
03	1960	1987	2019	1951	1990	1999	1987	2014	1989	1996	2068
02	1972	2016	2052	1983	2021	2039	2014	2048	2016	2035	2098
01	1999	2046	2080	2014	2053	2073	2043	2079	2052	2070	2152
1	2028	2079	2109	2046	2082	2098	2077	2109	2079	2095	2163
2	2034	2088	2127				2088	2124			2174
3	2039	2106	2138	2066	2109	2124	2106	2134	2104	2120	2185
4	2086	2124	2161				2120	2158			2208
5	2118	2167	2205				2163	2201			2230
5½	2133	2197	2237				N/A	N/A			N/A
6	2165	2232	2269				2228	2266			2291
7	2194	2262	2295				2259	2291			2307
8	2212	2280	2320				2277	2316			2372
9	2235	2300	2336				2295	2332			2403
10	2284	2345	2381				2340	2377			2426
11	2322	2361	2399				2359	2394			2437
12	2345	2383	2419				2379	2419			2471	2439
13		2428	2458				2410	2455				2460
13½		2466	2493
14		2489	2523				2530	2491				2548
14½		2527	2568
15		2583	2602				2595	2608				2606
15½		2617	2633
16		2655	2687				2651	2683				2716
17		2694	2709				2691	2705				2754
18		2736	2746				2732	2743				2772
19		2772	2786				2768	2782				2806
20		2811	2824				2808	2820				2847
21		2851	2860				2847	2856				2883
23		2890	2898				2887	2894				2921
26							2892	2921				2950
27							2937	2961				2984
28							2946	2971				2995
29							2955	2993				3018
30							2977	3009				3029
31							3022	3054				3061
31½							3063	3088				3090
32							3103	3123				3123
32½							3124	3146				3135
33							3150	3166				3169
34							3195	3198				3205
35							3243	3243				3245
36							3268	3265				3279
37												3308
38												3362
39												3389
40												3425
41												3578
42												3659

Orton Cone Chart