i was told by a hairdresser that washing it in head and shoulders shampoo fades the colour faster.
Yes that would fade it faster....the pH is a little high if you would like to keep your hair and scalp in its best condition.
When you applied the color did you mix 2 things together, twist the top and shake 2 suspended liquids together or were you able to apply it straight from the bottle with out mixing anything?
If you mixed 2 things you used a long lasting semi permanent, or what the pro's call a demi permanent. They usually contain a very low volume of peroxide and little or no ammonia, they use a different chemical to cause the oxidation instead of ammonia.
If it came straight from the bottle to your hair it was a direct dye or preformed dye molecule in an alkaline solution. The alkaline liquid causes the hair shaft to swell so that the large molecules of color will penetrate slightly into the cortex (the center of the hair inside the cuticle) as well as sticking to the cuticle. This is the principle that the washes out in 15 - 20 shampoos works, the cuticle can't lie completely flat again because the colored molecules are in the way so each time we shampoo or wet our hair the cuticle raises or swells slightly and the rubbing action of our hands while we lather pulls a few of them off. Eventually we have none left and our hair is back to nearly its orginal state.
The long lasting semi permanent or Demi uses either MEA (methyl ethyl alamine )or AMP (amino methyl propinal) in place of the ammonia to oxidize the peroxide and cause the indirect dye molecules to come together and turn into a color. While this is considered Demi permanent because it does not lighten natural pigment, it penetrates and stains more deeply than permanent color. If this is what you used, you will need to go to a professional to have it lightened or refreshed. It is not something you can do successfully at home. (It is less expensive to have it done right than to spend the amount necessary have it fixed....we are in a school and corrective color starts at a higher price than regular color, usually it ends up costing 2X what it would have for us to have done it in the first place)
This is probably a whole lot more info than you wanted, but I can't help it, the teacher in me comes out and I have a hard time putting her back!
