Wikipedia
Hot comb
A hot comb (also known as a straightening comb) is a metal comb that is used to straighten moderate or coarse hair and create a smoother hair texture. A hot comb is heated and used to straighten the hair from the roots. It can be placed directly on the source of heat or it may be electrically heated.
Usage examples of "hot comb".
Bond took in the artificial parting traced with a razor across the left side of the scalp, through the almost straight hair which was a tribute to his mother's constant application of the hot comb since childhood.
Charlese, a pudgy man in his mid-thirties, with a crown of brownish gold hair gleaming like a helmet fashioned by hot comb and lacquer.