Developers are creams that contain hydrogen peroxide, the chemical that activates your hair dye and makes it possible for the pigment to penetrate your hair fiber.
They help lift your cuticle open so that the actual dye can have room to enter and seep into the hair’s cortex. This is what makes the color last longer in your locks.
Photo Credit: hairfinder.com
If you don’t activate your hair dye with a matching developer, the pigments or color molecules would simply sit outside your hair strand instead of penetrating them.
Photo Credit: hairfinder.com
Photo Credit: hairfinder.com
Photo Credit: hairfinder.com