If you need to cover your grey hair or want to try a different color for your hair, you would do well to forego boxed colors you get at the store, and instead have a hairdresser apply your color for you. While it can be cheaper to apply your own color, there are some good reasons to think about more than money when it comes to your hair care needs. Note why it's good to have a hairdresser apply your hair color rather than doing this yourself.
Color over color
One challenge you might face when applying a new color is that your current hair color is a very different shade or tone and you're not simply looking to cover grey roots; for example, you might want to go from blonde to red or from very dark hair to something much lighter. Doing this successfully often involves more than just putting color over your hair, as the dyes in hair coloring may not be strong enough to cover your current color.
On the other hand, those dyes may be so strong that the end result is a much different color than you imagined and not be very attractive. You may wind up with a dark color that looks muddy or a red tone that seems brassy. Your hairdresser will know if your current hair color needs to be lightened at all in order to provide a good foundation for your new color, or if you need to build up to a new color gradually so each shade looks natural and attractive.
Protecting hair from breakage
Adding color right over the entire strand of hair and allowing it to set for several minutes might weaken the hair and cause split ends and breakage. However, you might be concerned with how to dye the entire strand of hair to make it match the roots.
Your hairdresser can note how much of the strand needs to be covered with color for it to come out evenly, and can apply the hair color in sections: the roots first, then adding more color to the lower parts of the strand, then adding color to the tips, with each section sitting for just as long as necessary to absorb the dyes. This will keep your hair protected from damage while giving you an end color that is even in tone. Your hairdresser can also note if your hair needs a deep conditioning treatment or hot oil treatment before or after coloring to keep it strong without letting the color fade.