Classic hair straightening serum for curly hair, wavy hair, or frizz-hair: PHYTO Phytodefrisant botanical hair relaxing balm ($26-$32 depenading on size). AMAZE! What I love about this straightening serum is that it’s not greasy and it doesn’t weigh down my hair. When I apply it to my ends before blow drying straight it actually makes them light and super sleek! A must-have.