I know I could test and find out, but I keep thinking back to when I left a glass pan on the stove, and turned on the wrong side of the stove (thinking it was the other side) and having the pan explode loudly into a million pieces...if I was standing in front of it, I could have been blinded! Shit! So, I fear that would happen if I left a glass rod to heat up. I plan on heating it with candle light though, so. How long would that take approximately? Minutes or hours?