You feel it always. A metal at room temperature is colder to the touch than a plastic at that same room temperature. Unless they’ve both been exposed to some heat like strong sunlight, the metal will feel colder.
There would have been nothing wrong with that. But strangely, when you put the same amount of ice collected from one source on a metal plate and on a plastic plate in the same room, the ice on the metal plate melts first.
Isn’t this strange? If the metal plate is colder, then it should take a slower time to melt the ice, because that’s how heat transfer works. If I take two ice blocks of the same size from one source and put one in warm water and another one in very cold water, the one in the warm water should melt first and the one in the cold water should last longer. So how come metal which is colder when we touch it, tends to melt ice faster?
The secret to this phenomenon is your hand. There’s something wrong with your hand, not the metal. Your hand is not a thermometer! You feel the metal cold but it is not. And rightly enough, when we use a thermometer to check the temperature of metal, the result is something different from what our skin tells us when we touch metal.
Metal is not really cold. It is just a very good conductor of heat. That is to say, it gains or loses heat quickly from anything – including your hand. Metal conducts even body heat. The result is that as soon as you touch it, your nervous system gives you the message that this thing is cold.
Now to explain the ice, heat transfer works like this: When two things with different temperature are in contact, the one that is warmer and has more heat will lose heat to the colder one. The one which is colder with a lower temperature, will gain more heat and even melt if need be, until the two reach thermal equilibrium (have the same temperature).
In the case of ice on a metal plate, the metal’s higher thermal conductivity makes it lose heat faster to the ice. The result is that the ice melts faster on the metal plate than on the plastic.
So the thermal conductivity of metal results first, in you feeling metal cold when you touch it with your skin because it draws a lot more heat from you. A thermometer will say something else about the metal’s temperature though. Second, metal is able to “heat” ice faster than plastic.