Cold fusion extensions are a relatively newer method of applying for the bonded hair extensions. Unlike the hot fusion extensions where the applicator is around 220 degrees, the cold fusion applicator uses ultrasonic waves instead of heat to melt the keratin just enough to make it pliable. The ultrasonic waves then directly attach the extension to the root of the natural hair without the keratin tips actually mixing with the real hair. The cold fusions can look more natural than the hot fusion because it is easier for the technician to create a neat, flat bond.
Cold fusion extensions are less damaging than hot fusion extensions for a couple of reasons. The heat from the hot fusion extensions can potentially be very problematic as if it is not applied correctly the heat can burn the hair and scalp causing permanent damage. The fact that no heat is used on the real hair means it is a much safer, gentler method of fusion extensions. The removal process of cold fusion extensions is a lot gentler than hot extensions as it does not require the use of acetone to break the bonds, acetone is a damaging chemical to natural hair.