We know the dangers of UV on the skin, which is an organ. But we tend to think that they are harmless on the hair, since it is an inert material (the lengths are not alive). And yet… UVB rays are formidable:they attack the structure of the hair by oxidizing the bonds between the strands of keratin that compose it. Once these bonds are broken, the fiber is no longer smooth, it reflects light less well and risks breaking. And UVA alters the artificial pigments of the color and gives it a bland side. In question ? Their wavelength which makes them penetrate deep into the fiber. On natural pigments, their effect is less important, but real. In short:a hair that turns blond in the sun is nice, but it is above all a sign that it is oxidizing and damaged.
The most effective is the hat, which prevents UV from reaching the fiber. And, if we have long hair, we tie it up. Don't want to cover your head? You must use sunscreen with a UV filter. The filters used in hair formulas are the same as those selected to protect the epidermis. In absolute terms, you can use the same product on the skin and the hair, but it's not always very nice in terms of texture (unless it's an oil). There is no universal index of hair protection, which would be the equivalent of SPF for the skin. Only René Furterer has developed an index, the KPF, which measures the percentage of preserved keratin. For the others, it is difficult to know the level of protection. We can just check in the list of ingredients that we find the name of a sunscreen (often, it is ethylhexyl methoxycinnamate) and that it appears in the first ingredients of the list (=in sufficient quantity ).
It is recommended to apply the protection before exposure then, if you stay in the sun, to reapply every two hours (as on the skin). The dosage, which depends on the galenic of the treatment and the type of hair, is indicated on the product. Otherwise, we keep in mind that we should not grease the hair, so we apply the product gradually. After the exposure, we shampoo and take care of the fiber with a restorative treatment.
Thanks to David Baco, René Furterer formulation laboratory manager.
