I'm going to purchase Redken Color Gels in red colors I am a natural dark blond which developer should I use?

Question

What is the difference between the Color Gels Developer 10, 20, 30, and 40?

Answer 1

40 is for maximum lighting 3-4 levels, 30 for 2-3 levels of lighting, 20 for 1-2 levels of  lightning, 10 for depositing depth.  

As for which developer to use-it depends on how bright and light you want to go with red.  If you are using a red shade that is darker than your current haircolor use 10.  If you are going lighter use 20.  I wouldn't use more than 20 with a red unless you are going for super vibrant shades.

Answer 2

The shade, 40 is darker. Don't use Redken, it riuned my hair. Just a warning.