What exactly is hair filler and how does it work? Calling all hairdressers!?

What is hair filler? I heard it's used to put on blondes who choose to go brunette or to their natural color along with a demi-permanent dye. My question is, what is it, how does it work, is filler harmful to your hair and does it really turn an ';orangish color'; even if you tell your colorist you want to go to an ash tone in the light brunette shades.


I'm debating whether or not to have the dying process done or to let it grow out-which my hair is light blonde and LONG. Cutting it short is not an option! Hairstylists/colorists, please help!11111111111111What exactly is hair filler and how does it work? Calling all hairdressers!?
Natural hair contains the three primary colors red, blue, and yellow. When you are trying to go from blonde to a darker color, it is very important to use a filler to replace the missing pigments. When you apply the filler it will turn an odd color, but when you put the darker color over it, it balances the hair out. Failure to use a filler could result in your hair looking very muddy or even green when using an ash color formula or a pinkish orange if using a more red formula. After you apply the filler to your hair, you should let it sit for about 10 minutes and then blot off the extra color. After you have blotted the entire head you can apply the color you choose over the filler and let it process for it's recommended time. The filler itself will not damage the hair because it usually is a direct dye. Demi-permanent colors are ammonia free and will not cause any damage either, however, if you use a permanent haircolor be sure to do a conditioning treatment. Hope I helped.