I have a 3-sided fireplace, which means it has 3 glass panels that have a few millimeters of gap between them, enough for the space to smell like smoke. I applied it between the glasses, and so far it has done a very good job!

Caution: It dripped a bit on the tile and wouldn't come off completely (it left a haze) even with gasoline, alcohol, etc. However, it came off very easily with Cif.

Use on a 2mm black iron drill bit. In a spot where it was shaken, it tore, it does not have elasticity, but where it was applied well, it holds up even in very high temperatures.