I'm not certain, but I think it opens up the cuticles to let the product absorb like dc'ing with a plastic cap & heat or steaming. I like to do this when I apply a conditioner as a leave-in. It seems like otherwise the leave-in just sits there. I've only been doing it for about a month though. I just make sure to lightly blow dry though until the product disappears-not enough to actually dry the hair...I think that might cause heat damage.