Imagine that you’ve just spent a fortune on a piece of clothing and you want to keep it in perfect condition and wear it for as long as possible. How would you wash it? In a washing machine with a cheap detergent that contains aggressive ingredients? Or handwash it with a detergent that’s more expensive, but gentler and more pure?
Now, for your hair: You’ve just spent a fortune (and many hours!) on a new hair colour and you want to keep it looking fresh for as long as possible. How would you wash your hair? With a cheap shampoo that contains aggressive ingredients or with a gentler, purer but more expensive shampoo?
As for with your clothes, the lifetime of your new hair colour will be affected by washing, depending on your choice of shampoo. More importantly, depending on the ingredients of that shampoo. To maximize the lifetime of your new colour, there are several ingredients to avoid as they can be aggressive and wash out a new colour.
In cosmetic hair science, there are objective ways of measuring the damaging effect of a shampoo on hair. Two such measures are: (1) the loss of protein (mainly keratin) generated by the shampoo and (2) the amount of trans-epidermal water loss through damages caused to the lipid barrier of skin. In other words, the amount of water lost through the skin due to damage.
When choosing a shampoo to preserve a dye job, there are three families of ingredients to avoid because they all score very badly on the aggressivity scale : sulfates, ingredients starting with sulfo and ingredients ending in isethionate.
There are several variants: sodium lauryl sulfate, sodium coco-sulfate, sodium laureth sulfate, or any ingredients that end with sulfate.
2. Ingredients beginning with sulfo
These ingredients have a comparable chemical structure to sulfates and share a common element: sulphur. Some commonly found variants are sodium C14-16 olefin sulfonate and disodium laureth sulfosuccinate.
3. Ingredients ending in isethionate
These are commonly hidden behind sulfate free claims. One variant that some studies say is more aggressive than most sulfates is sodium cocoyl isethionate.
Finally, the two last ingredients to avoid in your shampoo are cocamidopropyl betaine and cocamide DEA.
Mentions and allegations stating that some shampoos are ‘’sulfate free’’ are, these days, very common in stores. Are those enough to say that the product is safe? Our answer is: NO! You need to look beyond these statements and look for the ingredients mentioned above. Even in shampoos with logos that claim to be organic, sulfate-free or formulated to protect color, you could find these aggressive ingredients, which in the end, will not help the life span of your colour.
In short, the best guarantee for your coloured hair is a shampoo that is 100% natural, without sulfates and none of those bad ingredients mentioned previously.