Clean Hair and Semi-Permanent Dyes

Semi-permanent hair color
Photo: ThamKC/Shutterstock
Q: I love to try funky colors on my hair, and my mother has always advised me against washing it beforehand. She says the oils on my head after not washing will hold the color better.
So, rather than reading the instructions, I would just go without washing my hair for a day or two, apply the dye like it was shampoo, leave it for a certain amount of time, and then rinse until the water was clear, shampoo, add the tube of conditioner if needed and go on about my day.
Of course, these were all semi-permanent dyes anyway, so it didn't matter if it didn't last as long as necessary anyway.
Now, I am doing this on my own. When I bought the dye, I actually took the time to look at the instructions and discovered that step one is to shampoo (no conditioner) and dry my hair. Make sure it's clean and all that. My question to you is this: Does it really affect the dye job if my hair is clean?

A: Actually, it does have an effect. In most cases, color application or other chemical services need to be performed on clean hair. With color, it needs to be clean and dry hair. The presence of too much natural oil on the hair can inhibit the penetration of the coloring agents. The end result is a lessening of the color intensity and/or a shorter-lasting color.
On the plus side, even with semi-permanent dyes, applying the color with a couple of days' worth of natural oils in place has likely helped to protect your hair from potential damage due to repetitive processing. It isn't necessary to wait more than a day, however.
You can simply wash the hair one day and do the color the next and get reasonable results with adequate protection from damage. The biggest reason for the recommendation to wash and dry the hair before coloring is to make sure you don't have any styling product in your hair.
Having styling product in your hair can cause uneven color results, and for women who use such products daily, you have to make sure to clear away the residue of these products to make sure they don't interfere with the color process. Having clean hair can give you not only even color results, but can help the color to last longer.
See also:
Hair color application
Semi-permanent hair dyes
Should hair be newly cleaned without product for a successful color treatment?
Can I shampoo my hair as soon as I wash out my hair color when dying my hair?