A quick search with Google yielded the following information. All values are in degrees Celcius.
Melting point of glass: around 1400-1600
Melting point of iron: around 1500
Melting point of steel: around 1300
I've always imagined heat vision to be something like laser and the scope of what's considered "laser" is very wide. Anything from LEDs to the super-duper-cuts-glass-and-steel-in-industry sort are "lasers".
There may be a laser around which can pass through glass easily withour damaging it and yet still heat up guns enough to cause pain. Or there may be not. Can other folcs comment?
In any case, I recall that anything at 60 degrees Celcius is already too hot for the human touch and is sufficient to cause minor burns (DocJill, correct me if I'm wrong).
Wendy, this section is as usual, waffy and rather fun to read. However IMHO, please hurry up and just get rid of Luthor, send Lois and Clark to Smallville to meet Martha and Jonathan, create Superman and introduce him to the world via the Planet.
Then the smoochies can begin.
