good cup/bad cup

I'm trying to make this blog more than just a place where I dump my PD370 projects, so here are two cups that use different means to insulate the hand from hot beverages. One of them is dumb.

The Good: Bodum Canteen glass

I have a couple of these, and they rock. They're made from borosilicate glass (the same as labware) so they weigh almost nothing, while still being strong enough to survive being dropped in the sink. The lightness is kind of cool on its own, but it also keeps it from sucking all the heat out of your coffee. The rim is a little wide, but that's kind of unavoidable with the double walled construction. Most importantly, they work. The insulating layer of air keeps your fingers cool and your coffee hot, and in the summer it keeps cold drinks from 'sweating' which I guess is nice because I don't have any coasters.

The Bad: Radiator Mug by Stephen Reed

I don't own these, but I do have a half-assed understanding of thermal dynamics, which is enough to make me not want them. They undertake the same goal as the Bodum cups, protecting your fingers from hot drinks, but instead of using an insulator to keep the heat inside the cup, they use fins to spread that heat over a wider area. This probably does a decent job of keeping your fingers from getting burned, but it does a much better job of making your fresh cup of coffee go cold. Why? Because that's what a radiator is designed to do. Take heat from the liquid inside, and radiate it to the air outside.