What is this fusion hair extension method people have been talking about? Fusion hair extensions is the process by which human hair extensions are attached to your natural hair with the help of keratin tips glued at the tips. Commonly Human Hair that is made for braiding or Bulk is used for this method of fusion. The glue needs to be melted to your original strands of hair then attached to your original hair. This bonding strategy is known as hot fusion or thermal fusion. The new method of fusion would be the cold fusion method. Cold fusion is done by melting the keratin tips already on the extensions to your own hair. A tool primarily made for fusion must be used to implement this method. The device uses ultrasound waves to bond the extensions with your natural hair. Sounds like straight out of science fiction doesn't it? Cold fusion has been gaining more and more popularity because it claims to be more gentle on the scalp than hot fusion. Fusion hair extensions are highly durable. This means that extensions could last up to 3-6 months. Both fusion techniques also give the wearer an invisible method to implement these hair extensions and a more natural look. They are also quite a bit more expensive than the other methods of applying extensions.