Tin has high conductivity for heat, but a low melting point. It cannot sit on a heat source without some liquid within it. If we put it on the burner, to make a rasam, we cannot leave it until the rasam is done, and it is taken off the burner. Not fit for the absent minded multitasker, or for making things that do not have a liquid'y consistency. Even tin coated brass vessels should not be heated on their own and left unattended.