Unless the shampoo is specifically designed to be used as a daily toner, applying purple shampoo every time you wash your hair is typically discouraged because it can begin to eliminate too much yellow from your hair.
The purple shampoo can cause build up making the hair look dull and darker if overused." This makes the lightening process more difficult to create a seamless blend.
DOES PURPLE SHAMPOO DAMAGE HAIR? The cool violet pigment in purple shampoo won't damage hair, but if you leave it on strands too long, those purple pigments will take their job a little too far and could turn tresses a purple-violet colour.
Unless the shampoo is specifically designed to be used as a daily toner, applying purple shampoo every time you wash your hair is typically discouraged because it can begin to eliminate too much yellow from your hair.
If you leave purple shampoo on for too long, you may find yourself with a little lilac hue. This color is not permanent and is more likely to happen if you have very light blonde hair or if your hair is dry and damaged. To remove the purple hue, switch to regular shampoo for your next few washes.
Purple shampoo is for already bleached hair, so if you're hoping to lighten brown hair with purple shampoo, you'll be disappointed. This is all down to the fact that purple shampoo isn't lightening. Instead, it brightens blondes by canceling out yellow tones, which just happen to be opposite purple on the color wheel.
Using a purple shampoo on grey hair can help to remove brassy yellow shades, leaving you with a flattering silver undertone.
Everyone's hair is different, but we recommend using it once every week or two, then building it up from there until you find your own cadence. Just know that it is possible to overdo it—especially if you have high porosity hair—which results in a (temporary!) purple tinge.
If you have platinum, gray, or silver hair, you can leave the purple shampoo on for up to 30 minutes, depending on how brassy or discolored your hair is.
For grey hair coverage, we generally recommend that you aim to color slightly lighter than the natural hair color level of your client. In this case we would suggest you go for a color starting in level 6 (Dark Blonde) or 7 (Blonde).
If you've got gray hair, purple shampoos are now officially your new best friend. They'll remove all the unwanted brassy and warm undertones that taint your beautiful silver color, leaving you with bright, shiny locks.
Purple shampoo neutralises brassiness but enhances blonde pigmentation. To maintain a silver shade, your shampoo requires a stronger colour neutralisation. Silver shampoo is formulated with deeper purple pigments to target yellow tones in a much stronger way.
Purple shampoo works the same way to eliminate brassiness on brown hair as it does on blonde. It helps to prevent color fade, while emphasizing shine, keeping brown hair vibrant and rich. Using purple shampoo on brown hair regularly will take out any unwanted warm tones in your strands.
Because it does not contain an ingredient that will chemically change the color of your hair, purple shampoo cannot truly lighten hair. If anything, purple shampoo may make your hair temporarily slightly darker.
How Often Should I Use Purple Shampoo? Keep in mind that purple shampoo does not replace your regular shampoo and should only be used once or twice a week.
Purple shampoo has been used for decades by hairdressers, mostly to help tone and neutralize blonde and gray hair, getting rid of brassy or yellow tones for an overall more cool-toned look.
Purple shampoo is the best toner to use when it comes to gray hair because it neutralizes brassiness caused by heat styling, medications, product buildup, sun, salt, chlorine and environmental pollutants.
Colors like butterscotch, light auburn and golden brown, or ash brown for those with a cool skin tone, are all versatile brunette shades that aren't too dark and are some of the best hair colors to hide gray.
Neutral shades like soft blonde, mushroom brown, light copper, and caramel blonde balayage are the easiest to blend gray into (and maintain over time without wanting to shave your hair off).
Demi-Permanent or Semi-Permanent Color
You can also try semi-permanent Color Fresh for up to 30% coverage. While a demi-permanent or semi-permanent hair color can be applied to any level of gray, it's often used to camouflage early grays, giving 30-70% coverage.
Saying that, it does lather and in turn remove some build up from the hair, but I would advice you wash your hair with a normal shampoo first before purple shampoo, especially if you find your hair needs washing daily or hasn't been washed for a couple of days.
Zoe's answer: Leaving purple shampoo in your hair for longer than the recommended time is not always a good idea. The longer you leave it, the more pigments will be deposited on your hair and they could even stain it permanently.