After receiving the keratin treatment from your stylist, your hair cuticle will be opened up. This is because the amino acids have the ability to penetrate into the cuticle among all other minerals and vitamins. As a result, it is perfect for your hair.
Nevertheless, the keratin treatment really changes the color. It is always a little bit lighter, and in your particular case, it is yellow.
Everything which needs to be done is applying a toner.
It is possible to use a purely violet toner. It can be found at specialized beauty supply stores.
Half of a tube should be mixed with 10 volume peroxide. It is recommended to make the consistency like runny yogurt.
Apply the toner to the hair within 15 minutes. After this time, it will quickly change. The yellow color, as well as the yellow patches on your scalp, will be gone.