Roots too light - when and how to re-dye?

[Yakira]

Hi
I use Koleston Perfect, 7.0. I have long thick hair, that would really prefer to stay white - but the Koleston generally give me perfect coverage.
I went to have my roots done. I shampooed the day before, as I always do.
I noticed that the hairdresser put in more developer than I use, a full bottle of 6% to 3/4 of a tube, whereas I use 1:1.
It was on my hair for nearly 45 minutes, as usual, but the roots are much lighter than usual...you can see the white through a thin layer of color.

Is this possibly because she used more developer.? How and when can I reapply?
Thanks

 

[Yakira]

Sigh...

 

[Noodle]

Hello and welcome to the site.

Unfortunately, none of our hair professionals are permitted to give specific colour details or techniques to those who are not hairdressers themselves.

You will appreciate that they have trained for many years, spending time, hard effort and money to obtain their qualifications.

Perhaps to should be addressing these questions to directly your hairdresser, instead of experimenting with attempts at home colouring without the necessary training.

After all, the results could be more harmful and damaging than you realise, not to mention the visual outcome.