On Thursday, June 4, 2015 at 8:06:17 AM UTC-4, John B. wrote:
It is easy to do,
just paint the area with a marker - permanent or white board - and
then heat the area with a torch until the marker goes away.
Interesting - i'd never heard of using a marker as a heat indicator. Any idea what temperature that "vanishing point" would indicate?
I've always used these:
http://www.tempil.com/products/tempilstik-original/