Food - Drink
The Real Reason Cold Cream Doesn't Affect The Temperature Of Your Coffee
By AUTUMN SWIERS
Pouring cold cream into hot coffee can sometimes cause the creamer to coagulate, due to the sudden heat shock, but the coffee itself does not drop drastically in temperature. This is because of the Stefan-Boltzmann Law, a scientific rule that notes how different surfaces radiate (or lose) heat.
The Stefan-Boltzmann Law states that "hotter surfaces radiate heat faster," and you may have heard that darker colors are "hotter" than lighter colors. Since black coffee is darker, it loses heat more quickly than lighter coffee; coffee with cold creamer added may cool down a bit at first, but overall, it cools down 20% slower than black coffee.
Also, thicker liquids with higher viscosity retain temperature better and cool down more slowly. Different types of creamers will add different thicknesses to your brew, affecting how quickly it cools, but all creamers contribute to hotter coffee for a longer time, even if your creamer is very cold before it goes in.