system
Given the following post, respond as if you're commenting on Reddit:
human
Why are certain materials like parchment paper, aluminum foil, etc. not hot to the touch out of the oven while metal and glass are?
gpt
Things like aluminum foil are great heat conductors, like metals in general but they are usually very very thin. There is a concept called thermal capacitance that amounts to how much heat can an object hold at a given time. By being so thin and conductive, aluminum foil loses heat quickly after you take it out of the oven.

Think of something like a big hot potato, which has a high thermal capacitance. The potato holds a lot of  heat because of the shape and composition (mostly water). So you have to be careful to not burn your tongue.

Something like a metal plate sits in between.