Applying hair colour to hair that has been previously lightened can sometimes be a challenge. During the lightening process, hair colour or bleach removes some of the pigment from hair and makes the hair shaft more porous. A protein filler is needed when applying a darker shade of colour over pre-lightened hair. The protein filler will prevent the dark colour from fading by filling in some of the overly porous hair strands, and prevent porous hair from grabbing too much of the colour base.
Purchase a clear protein filler from a local beauty supply store. Most supply stores offer small sizes of filler that are ideal for one-time usage.
Shampoo the hair using a mild shampoo. Do not condition hair, as conditioner can prevent the protein filler from penetrating the hair shaft properly. Rinse the hair well and towel dry.
Apply clear protein filler. Empty tje contents of clear filler into a small spray bottle. Spray hair thoroughly, paying special attention to the ends where hair tends to be more porous. After the filler has been applied, comb through hair to make sure filler is distributed evenly.
Let the protein filler process. Depending on the brand of filler purchased, processing time may vary from five to 10 minutes. Do not rinse.
Apply hair colour. Hair colour should be applied directly over the protein filler and processed as per box instructions.
Using a clarifying shampoo before applying protein filler will help remove excess product and environmental residue from the hair, allowing filler and colour to penetrate evenly.
Protein fillers that contain a colour base should be avoided. Coloured protein fillers are used for colour correction and can be tricky to use if you are not a trained professional.