Rich Waugh
Platinum Member
The brand name of the temperature crayons Curly mentioned is "TempilStick", made by the Tempil Corporation. They're available in temperatures from about 200 all the way up to around 2000F. Very handy for pre-heating for welding on tool steels and cast iron, as well as heat treating carbon steels. Welding shops carry them and you can also get them online.
Rich
Rich