I just don't understand. Why would a direct flame on a boro. flask be ok, but heat from an electric element pose a problem? I'm really not being snarky. I want to know what's going on here because I've always used my flask on my electric stove, and I want to know if I've been putting myself (well, my kitchen stove) at risk this whole time, and the reason why that is.
I understand going from hot to cold quickly and vice versa is not good. The glass will expand/contract, etc. I'm talking about putting some room temperature water and DME in the flask, putting it on the electric stove, and bringing the heat on it up to a boil slowly. Why is this a problem?