What straightening, smoothing and perms do to your colour

Thinking about Straightment, Wavement or a perm, and your hair is coloured, highlighted or toned? Texture treatments work in the same depth of the hair as colour, so they can change it. They can fade colour, remove the toner or shift the tone. Here’s what’s going on, and how to time things.

Why can a texture treatment change my colour?

Texture treatments work in the same depth of the hair as colour. That’s why they can change it.

In a perm or Straightment PERMANENT, a thioglycolate cream breaks the hair’s disulphide bonds. A neutraliser then re-forms them in the new shape. UK law caps thioglycolic acid in these products at 8% for consumer use and 11% for professional, at pH 7–9.5. So this is serious chemistry, not a styling product.

What happens to toner?

Toner goes first. It’s mostly demi-permanent colour, sitting mainly in the cuticle and outer cortex, put in with a lower-strength developer. On its own it often fades after 10–15 shampoos. Add a texture treatment and it can be removed altogether.

That’s why your toner receipt matters. It’s part of your hair history, and I want to see it before we plan anything.

What about highlights and bleach?

Heat from straightening oxidises tryptophan in the hair protein, which yellows hair. It can yellow white hair and darken bleached hair.

A published review also advises waiting after chemical straightening before demi-permanent colour. It warns that highlights and light shades combined with chemical relaxers risk breakage. What you follow is my rules below.

If your hair is heavily lightened, we talk first. Full piece on highlights: will straightening ruin my highlights?. Your bleach history matters too: bleach damage.

When should I colour: before or after?

Depends on the treatment.

My rules

• Straightment DEMI: I prefer colour after the treatment.
• Straightment PERMANENT, Wavement COLD and other perms: colour at least 2 weeks after.
• Other salons’ keratin systems: follow the product.

One more thing on keratin: keratin is not a treatment. It’s a general word for smoothing. In my system it’s a Semi or a Demi. Elsewhere it could be anything, so with someone else’s product, the product’s instructions win.

Can anything rule out straightening completely?

Yes. Manufacturers forbid straightening over hair treated with metallic-salt dyes. That’s Wella’s own position. If you’ve used any dye with metallic salts, or you’re not sure what’s been on your hair, tell me. Honesty at the consultation is cheap. Sorting out the alternative isn’t.

So what’s the plan?

Simple. Tell me your full colour history: colour, highlights, toner, box dyes, the lot. We pick the treatment, then we sequence the colour around it using the rules above. Done in the right order, you can have the texture you want and the colour you want. Done in the wrong order, you’re paying twice to fix one of them.

Sources

• Heat, tryptophan oxidation and yellowing: https://ncbi.nlm.nih.gov/pmc/articles/PMC4387693/ and https://library.scconline.org/v049n04/13
• Toner and demi-permanent colour: https://ncbi.nlm.nih.gov/pmc/articles/PMC4387693/ and https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4828511/
• Metallic-salt dye warning (Wella UK): https://uk.wella.professionalstore.com/product/permanent-straightening-cream-for-coloured-hair/000000099350188284
• Thioglycolate and neutraliser chemistry: https://onlinelibrary.wiley.com/doi/full/10.1111/ics.12093 and https://uk.wella.professionalstore.com/product/neutraliser-cream-to-be-used-as-2nd-step-for-straightening-1000ml/000000099350188131
• UK thioglycolic acid limits: https://www.legislation.gov.uk/eur/2015/1190/annexes/data.xht?view=snippet&wrap=true
• Waiting after chemical straightening: https://ncbi.nlm.nih.gov/pmc/articles/PMC4387693/