funny thing happened on the way to the casting pot

[Smoke4320]

been reading all I can here and kept wondering why everyone keeps quoting 700 to 730 casting temps for NOE molds. Mine seemed to work very well at the indicated 650 on my Rotometals purchased casting thermometer so I just kept my mouth shut ..
well yesterday I received my Frozone PID plugged it in and started the pot .. set the temp to 650 and let it heat up .. for giggles after it reached temp I dropped the old thermometer in the indicated 650 degree lead.. My word the old thermometer reads 580 degrees
THE question I never asked was answered... I was casting at 720 all along :) :)
made a sticker for the old thermometer +70 degrees

[zuke]

I would just toss the old one.

[williamwaco]

I find the temperature can vary by that much from one spot to another in the same pot.

Try stirring the pot before you measure the temp.

I set my thermometer so that the tip of the prob is about one inch above and one inch behind the pouring spout exit.

[Mk42gunner]

My word the old thermometer reads 580 degrees THE question I never asked was answered... I was casting at 720 all along
made a sticker for the old thermometer +70 degrees

That is why I just use my casting thermometer for reference. I haven't seen any of the ones that are sold for home casting use that are easily calibrated.

Sure you can stick it in a pot of boiling water, but ~212°F is a long way from 650 or 700°.

Robert