You'll hear varying advice on how long to wait to shampoo after a perm.
Some stylists suggest you wait 24 hours before shampooing, while others
swear it's at least 3 days. The truth is, it all depends on your hair. To
counter the claim made by the movie "Legally Blonde", you won't 'risk
deactivating the ammonium thioglycolate by getting your hair wet within 48
hours'. The waving lotion has done its job and been thoroughly neutralized
if the process was performed correctly.
However, perming the hair is a strong process, and you have to pay
attention to what your hair tells you. It's never a bad idea to give your hair a break after
a strong process. Remember that the alkaline of the waving lotion has raised the cuticle
of the hair and made it more porous, therefore it will feel drier and rougher, so use a
good conditioner, and a milder shampoo. Acid balancing shampoos and conditioners are
available from many makers, and you can always rely on your salon professional to
suggest something suitable to your hair type.
Perms & Haircolor:
Also, do bear in mind (especially if your hair is color-treated) that perming the hair
can result in lightening of the color. The most common ingredient in perm neutralizers is
hydrogen peroxide, which is used as a developer for permanent haircolor formulas. With
the cuticle already being raised in the process of waving, the peroxide readily penetrates
the hair and will break up the color, though the peroxide solution is much weaker in the
perm formula than in haircoloring.
This is also the reason that you want to have your hair permed before coloring it.
Otherwise, you risk fading the color. As for how long to wait between perming and
coloring, talk to your professional, and ask them when they think your hair is in the right
condition for the subsequent color process.
Hopefully, this gives you enough information to understand how a perm works and lets
you take better care of your hair. After all, you want to look your best, and beautiful hair is a major asset.