Is There A Less Damaging Way to Straighten and Dye Hair?
Chemical hair straightening and dyeing are popularly used together, but both of these treatments are known to cause severe hair damage and protein loss. Permanent hair dye works by using ammonium hydroxide as an alkalizing agent to open up the hair cuticles, allowing dye molecules to penetrate the cortex of the hair shaft. Chemical straightening products work by using a high pH to break down the bonds within hair strands to augment the strength and shape of the hair. Recently, researchers sought to determine whether one chemical straightener is less damaging than another when both these treatments are desired.
The first study to evaluate protein loss from these combined treatments was recently published in the Journal of Cosmetic Dermatology. In this study, Caucasian curly brown hair tresses were treated with brown oxidative hair dye and three different straightening products. The straightening products were based on ammonium thioglycolate, guanidine hydroxide and sodium hydroxide. Hair protein loss was measured using a specific method called the bicinchoninic acid (BCA) method. Overall, relaxing and dyeing treatments were shown to be far more damaging when combined. A 208% increase in protein loss was observed in only dyed hair. When combined with the straightening agent sodium hydroxide, protein loss increased by 356%. However, the authors noted that there was no significant effect on protein loss on dyed hair also treated with ammonium thioglycolate or guanidine hydroxide.
Based on these results, the researchers suggest that ammonium thioglycolate or guanidine hydroxide are a better choice to chemically straighten hair than sodium hydroxide when combined with dyeing.
Byline: Katherine Fatheree, PA-S and Martha L. Sikes, MS, RPh, PA-C
Adapted from the original article.
[image by Wellcome Images]