Clients will always ask me if they need to wash their hair before they come in for a hair color service. And I am not talking about cement, mud on the hair and scalp. The answer is no. Hair color, perms, highlights, are all chemical services that are done in the salon and only in the salon. A buildup of oils, dirts in the hair will not be able to overcome the chemical strength of hair color or bleaches, or perms. They will not alter the chemical process of lifting or altering the hair structure of the chemicals being used in the service. in fact when clients come in to have a hair color service and the hair is wet the only thing that will cause a problem is the time spent blow drying the hair to proceed with the hair coloring service. And that is a fact Jack! Dirty hair (second day, third day is fine) makes it easier for the colorist to place foils in your hair. The natural oils also help protect your scalp from possible irritation the color could cause. Hair color is stronger than oils, and dandruff, dirty hair. etc.. Hair is a chemical and I have seen it clear off the scalp of and all natural oils and day to day grease and grime.
*EXCEPTION – The only exception to NEVER shampoo rule is chlorine. If you go swimming in a chlorinated pool the day of your color appointment, you must shampoo the chlorine out or there could be some funky results when the color reacts with the chlorine!