A hot comb is a metal comb that is heated, then combed through extremely curly hair to straighten it. Originally, the comb was heated on an open flame before being used. Nowadays, many hot combs are made in the same way as a flat or curling iron. The comb is plugged in to make it generate heat. After it gets warm you just pick it up and use it. Also, this comb can be heated over a fire or a stove burner. Once hot, remove the comb, shake it, and run it through coarse hair. This comb is used frequently by African-Americans and people of African descent. In the 80's and 90's use of the hot comb (also known as pressing hair) fell out of popularity for relaxers but has made a mild resurgence recently, due to the health benefits of smoothing a rough cuticle. Using a hot comb doesn't change the chemical structure of hair (although repeated use may denature the hair proteins, called hair training). Madame Walker's first product was a scalp treatment that used petroleum and a hot comb (it was used to heal scalp problems and not to straighten hair at first).
Damage
Hot combs can permanently damage hair: [1]
Heat from appliances like curling or flat irons soften the keratin of the hair (the principal protein in hair). Too much heat can actually cause the water in the hair to boil, forming tiny bubbles of steam inside the softened hair shaft and causing the cuticle scales to permanently bubble. The hair becomes brittle and weak and may break off. Keep hair dryers at least 10-15 centimeters from the hair, and constantly moving to avoid over-heating the hair.
