Thanks, Dan for pitching in: Nice blog btw.
Thanks for also pointing out the brittleness of wires, and that max temperature degrades with wire dia:
For instance: Kanthal A wire of 3 mm dia (not the average home shop kiln) could take 1350 deg,
but around 1 mm it'll take max 1250.


Sorry, Nick for perhaps being confusing in my previous post, I totally missed the obvious last night...
The discussion on IR thermometer and materials & temp is probably NOT relevant in your case.

I assume by "Wrong thermocouple" you meant you plugged a "K" type into a PID/ controller designed for a "J" type?

Then, IF you choose 600 C as the limit temp, the controller will open the throttle wide open,
until it gets 33 mV back from the thermocouple input.
Fine and dandy IF you'd hook a "J" type up, which will precisely return that voltage at 600 C,
- but a "K" type would give off 33 mV first when it's reached 830-ish degrees.
I guess this was exactly what happened
(but your IR thermometer could have had its emissivity factor off too, but NOT deviate by 200 degrees...)

Hope this helps!
Cheers
Johan