Type S thermocouples are rated for approximately 3000F and therefore are literally capable of lasting forever in a pottery or glass kiln application.

Type S thermocouples are made from Platinum and Rhodium, and therefore prices fluctuate as the price of platinum fluctuates. Type S thermocouples are accurate to +/- 0.25% (versus +/- 0.75% for standard Type K thermocouples). If your kiln uses green coloured thermocouple lead wire, then you have Type S.

If you are planning to upgrade your existing kiln from Type K to Type S, be sure to get instructions on the procedure. If your controller is not properly “told” that you have changed thermocouple types, you will over-fire your kiln.

It should be noted that Type S thermocouples are fragile, even though they are encased in a protection sleeve. If your concern is thermocouple life (versus accuracy), then an alternative is to consider buying thermocouple protection tubes for your standard Type K thermocouples. One knock with a kiln shelf could damage your Type S thermocouple and require you to replace it.