The best heat saver is tin foil. Cotton paper is going to absorb the heat and it will dissipate shortly after. Tin foil will keep heat in because it allows the air to circulate around the object being kept warm.
Tin foil is generally made of aluminum and can attract/transfer heat. Aluminium is widely used as cooling in computer systems, which spreads the heat all over the heatsink so the air can cool the aluminum down.
yes Answer: What is often called tin foil is actually aluminum foil/ When wrapped around an object it acts an an insulator reflecting heat. If the object is hot it reflects the heat back in, if the object is cold it reflects the heat way from the object (keeps it out)