What it is:
No.2 is not optional. No.2 is absolutely necessary after every single service when using Olaplex as it is a system. No.1 is meant to help mitigate damage during the color, lightening and relaxing process, however it cannot stop all of it. If it did, you would not get a visible result. No.2 is not an activator, neutralizer, sealer or conditioner. No.2 contains the same active ingredient as No.1. No.2 finds more single sulfur hydrogen bonds and cross links them back together without color, lightener or relaxers working against it.