3 ms·

I think the effect is more related to that water conducts heat well, while cereal pillow will function as insulator.

• masklinn 5y ago
  It's mostly a function of the rubber, while it's not a great conductor it's also not a great insulator. So the water will release heat relatively rapidly, and once it's cooled down to ambient temp the rubber will pull water from your skin if you touch it (it also tends to feel somewhat clammy in my experience). That's why wrapping the rubber container in a woolen or padded cotton cover mitigates the effect a lot, it will slow down the heat release, and once the water has cooled down it'll limit the heat transfer back into the container, and thus won't feel cold.