Olaplex Number 1:
Bond Multiplier is for professional in-salon use - and can be put on the hair as a standalone treatment, or if you're getting your colour done, it is mixed in with the bleach and put straight onto your hair in foils.
Olaplex Number 2:
Bond Perfector is then put on the hair once the bleach is rinsed out, usually at the back wash. This is left on for a good 20 minutes to really get the most out of its chemical mending.