Is there a SCIENTIFIC reason to wait between hair bleaching sessions?

People always say to wait and "let your hair rest" before trying to lighten a already bleached area. But, why? The hair is dead, it doesn't repair itself in that time between bleaching sessions.

Except for treatments like Olaplex that multiply the disulfide bonds in the hair (those bonds are what provides your hair with most of it's strength), treatments aren't actually FIXING anything so much as superficially masking the problem areas in your hair.

Don't get me wrong, I'm all for the maintaining your hairs integrity, and I know that some things aren't possible depending on each individuals personal hair. But lately I've just been wondering if there really is any REAL reason to wait?

If you are being careful, using only 20vol or lower with your bleach and you are protecting the clients skin and scalp as well, then WHY WAIT???

Say that time is not a factor, that you have as much time as the process requires to get you to the end goal of lightness. Why couldn't you:

  • rinse the initial bleach (that, lets assume, had olaplex added)

  • do an olaplex stand alone treatment for 30 minutes

  • do a post service treatment to return the hairs pH to between 4.5 to 5.5

  • rinse

  • rough dry the hair with care and a little oil to detangle/moisturize

AND THEN go for round 2 of bleaching that same visit?

You have strengthened the hair by using olaplex in your bleach and doing the standalone treatment, we assume you have addressed moisture with your product choices in washing and styling. You are NOT applying ON scalp the second round of bleaching, that would damage their scalp and hurt the client.

There just doesn't seem to be scientific reason to wait other than there possibly not being enough time in the day 


  • First of all, Olaplex is probably not really counteracting damage by strengthening hair (read this:

    Second, I assume that letting the hair "rest" is at least partly about insuring that the oxidation reactions are really completed. The reactions of alkaline hydrogen peroxide and hair proteins are complex and depend on the time it takes for the chemicals to diffuse through the hair. 

    I found one technical paper that says that normal bleaching breaks about 15% to 25% of the disulfide bonds in hair. More severe bleaching breaks as much as 45%.   So it could be that double bleaching is more aggressive in this sense. Allowing more time between bleachings to ensure there's no overlap between reactions that could compound damage is probably the scientific reason. 

    Source: Chapter 4, Bleaching Human Hair. Chemical and Physical Behavior of Human Hair, Robbins. 2nd edition.  
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