Dying it darker - Damaging??

I know that dying the hair lighter/bleaching can be very damaging to the hair in the way that it strips it..
But, would using a black hairdye on my dark dark brown hair do damage?
I have done this before, and the conditioners of the product seem to make the condition beautiful, but is there any undetected damage that comes with it?

I am dying my already dark hair to black using L'Oreal Paris Feria colour 3d (in 'blackest black') mainly so that as my hair grows, it will act as a marker, so i can see the actual growth.

So yeah, does it change anything in the hair?

As mentioned by Princess all colouring treatments damage hair, but going darker is less damaging. Can I also just point out, lol make sure your 100% sure you want to go with black, as its the hardest colour to get back out of the hair, especially if in future your looking for hi lights, just a thought, lol.

 

Karen:)