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Hair developer is the key ingredient that powers up your hair color so that it can work its magic and give you the luscious color that you love. It's what you or your stylist mixes with the hair color of your choice, to activate it so that it can start setting your dye. Developers are made of hydrogen peroxide, but there are differences between them.
Different Forms of Developer
Hair developers come in two consistencies, or forms, which are called crème or liquid. While they're both developers, their differences effect how you or your stylist apply the color to your locks. If your method of choice is squeezing the color from a tint bottle, liquid is the better option. If you're more of a bowl and brush kinda girl, or if you're using a coloring technique that requires precise control, crème developer is more likely what you'll need.
Volume is the primary difference between developers. It is an indication of strength and determines how much the hair color will be able to alter the color of your mane. There are four different developer volumes - 10, 20, 30 and 40. Of these, 10 volume is the weakest of the developers and 40 volume the strongest. Most at-home hair color kits come with a 20 volume developer which offers a medium amount of change. Occasionally 30 volume at-home kits are available.
Potential for Damage
Developers have the potential to cause a certain amount of damage to the hair. The level of damage differs from one level to the other depending on strength. A 40 volume developer, being the strongest, has the greatest potential to cause problems, such as hair breakage, and should be use only by a professional. The potential for trouble is even higher when developer is used on hair that's been previously damaged or chemically treated. For example, hair that's been relaxed should not have a 40 volume developer applied to it. On the other hand, the 10 volume developer has little chance of harming the hair and is safe for chemically relaxed tresses.
Final color results are another difference between developers. The stronger the developer, the more intense your results will be. If you have blonde ambitions, but your hair is three to four shades darker than you'd like, you're going to have the best results by using 30 or 40 volume developers, which are used primarily for lightening hair. A 30 volume developer lifts hair color up to three shades but does little when it comes to depositing color. A 40 volume developer won't deposit color or darken your mane, but is used for maximum lightening and lifts up to four shades. If you're only lightening your hair by no more than two shades, or want to darken your locks, a 20 volume will do the job. Use a 10 volume developer and you'll notice the least amount of change if your goal is to go lighter: generally one shade, if that. On the other hand, a 10 volume will deposit color and easily deepen or darken your locks.