Pressing
Comic book pressing removes many visible defects - thus increasing the grade - of comic books, magazines, pulps, treasuries, brochures, package inserts and many other types of vintage paper collectibles.
Slightly humidified comic books are stuffed with board inserts and are placed between layers of other materials in a heat press.
Comic books and other pressed collectibles remain under low heat & controlled pressure for several minutes to flatten, then cool and sit under even pressure and ambient temperature for a few hours to multiple days.