All hair dye is made up of two components - a developer and a colorant. The developer serves as an oxidizing agent - it activates the colorant and allows it to penetrate the hair cuticle. The colorants are pigments that saturate your hair. … see full wiki
I have been dyeing my hair for 14 years. I started out with burgundy, was blonde somewhere in the middle, and am now back to a deep red shade. Thus, I have much experience with home hair coloring and have used just about every brand out there. I am now loyal to L'oreal Feria because I have naturally blonde hair and red is a difficult color to "take" anyway - with other brands I noticed that my roots were coming in quickly and my hair wasn't very shiny. With Feria, I am able to go longer in between colorings and my hair looks shiny and healthy. Another bonus is that most hair dyes smell awful - Feria gives you a little scent packet that you pour into the mixture before you apply it to your hair and it gives it a nicer, more herbal scent and isn't so hard to bear for 25 minutes! The conditioner they provide is thick and smells wonderful and makes my hair feel silky and beautiful. I love this product!