Developer Debate, Bleach.

I wanted to help you to quell some of your fears about choosing the right developer for bleaching your hair. But first off, I wanted to tell you that it's really not that big of a deal, you will get similar results no matter what you use, it just may take more time.

Cream or Clear?

Developer comes in clear and cream forms. Clear is usually cheaper, and is basically just peroxide and water. Cream developer is similar, but it also contains conditioning ingredients, buffers, and glycerin. So cream developer is much better for bleaching hair, and makes everything a lot easier to use. 

Developer, cream or clear, also comes in different strengths, or "volumes". 10, 20, 30, 40 volume. The volume describes what percentage of the developer is peroxide. 10 volume is 3% peroxide, 20 is 6%, 30 is 9% and 40 is 12%, some places do have 50 volume, which is 15%, but it is usually only available to real professionals. 

I like to generally say that anyone can use 30 volume, it is a good standard that I always have a big bottle of around the house. If you're trying to go to "pale yellow" the colour to dye your hair any bright colour, 30 volume should be good if your hair is any shade of "brown" from a dark, chocolatey brown to a light brown, 30 volume should do the trick. 

If your hair is quite light already, you may prefer to use 20 or 10, but to be quite honest, I've never used either with bleach. 

If your hair looks black or really dark brown, save yourself a lot of time and go with 40 volume. 

My hair is really dark, it is black, thick and coarse, so bleaching it is a pain in the ass. To get my hair "pale yellow" enough to dye it pink, I bleached my hair twice with 40 volume. To get my hair as light as it is now, it's been bleached about somewhere between 4 to 7 times, with mostly 40 and occasionally 30 volume. 

Depending on how you bleach your hair, depends on how much you're going to have to do it. Freshly bleached hair doesn't bleach as much as dirty, stale hair, so waiting a few days in between bleachings may give you better results. 

I would highly recommend that you keep different developers around, especially if you typically need to use 40 volume. I always have a big ass bottle (946mL) of 30 and 40, and a small one shot bottle (120mL) of 20 volume. You may find one day when your hair still needs to be bleached, but 40 would produce too much lightening, and 30 will be better.

THE CONFUSING PART. 

You can achieve the same end result with 20 volume that you can with 40 volume but you would have to use 20 volume more times that 40 volume.

Some people think that it is better for your hair to bleach many times (waiting time in between) with a lower developer than to use a stronger developer once.