Does “Silver/Purple” Shampoo Really Cancel Brassy Colors?
Posted Feb 15 2013 1:01am
Makeup At Midnight says…Ever since I’ve been dying my hair blonde, I’ve been told by many people to treat my hair with a “purple/silver” toning shampoo or conditioner every few days to help prevent my hair from getting a brassy tone to it. Supposedly, this works by ‘color theory’ in the way that the purple toner in the shampoo is able to cancel out the brassy yellow colors in the hair. An example of such a product is the AG Sterling Silver line, one that I’ve been using myself (although I’m still skeptical). My question is, does these types of products actually work to keep brassy colored hair at bay?
The Beauty Brains respond:
There is a good bit of science at work here but don’t get your hopes up too high. Here’s why:
Back in the late ’60s or early ’70s companies recognized the need for shampoos focussed on the problems of people with gray or silver hair. Specifically consumers complained about their silver hair developed a yellowish cast. The yellowing effect could come from protein degradation, lipid oxidation or perhaps even residue from other haircare products. And it makes senses that it would be apparent on silver hair subtle shifts in color are more visible on such a light background (hair that doesn’t have any dark pigment). Regardless of the cause, women (and men) wanted some way to stop their silver mane from looking like it had been peed upon. (We exaggerate for dramatic effect but you get the idea.)
Enter an enterprising chemist who remembered the basic physics of the color wheel. The color wheel shows that colors that are at opposite positions on have wavelengths that will cancel each other. So, if one wanted to cancel the color yellow one would look across from their color wheel and find violet. Then, pulling out their trusty cosmetic ingredient dictionary, this chemist would have likely found that a dye, External Violet 2, which has two very important properties: first it produces an intense violet color and second it can stain surfaces like hair and skin. Being water-soluble Ext Violet 2 is is easy to incorporate into shampoos at sufficiently high levels where it can sustain hair. When done properly, this light violet stain is enough to counteract the yellow cast of hair thereby returning hair to its true silver shade.
Unfortunately, the effect of violet dye shampoos on blonde hair will be very subtle if there is any effect at all. Unlike silver hair that has a slight yellow cast that really stands out from the background, blonde hair essentially consists of ALL yellow shades. Canceling out a little bit of yellow on a very yellow background will be a barely noticeable improvement.
That doesn’t mean you can’t try it. If your hair has the right shade of yellow (brassiness) the violet may make a noticeable improvement. Just be careful because depending on the hair, the violet over yellow could give the blonde hair a greenish cast. It might be advisable to try the product on a part of the hair that’s not to obvious until the right routine is identified. Also, these dyes will build up if used repeatedly and depositing too much violet dye could leave your blonde locks looking like Purple Rain.