The bar is clamped in a metal vise, so the vise is very slightly heated and that side of the bar is much cooler.
Taken using the Topdon Android attachment.
I do have some kapton tape. I've heard black sharpie on masking tape too. The cutoff piece was definitely uncomfortable to hold but not in the range of instant burns; also a pretty dull surface. I wouldn't be surprised if it were a bit about 107⁰F but I don't think it was near 300⁰F.