Bleach
Before I bleach, I prep my hair and scalp. It's recommended that you do not bleach freshly washed hair because the natural oils on your scalp help to protect your roots and scalp from the harsh chemicals in the bleach.
Then I get ready to mix the bleach. I've been using Wella Blondor for almost two years, and it's done the job. I usually mix the bleach with a 40-volume developer, Welloxon Perfect 40, at a 1:1 ratio until the consistency is a thick, creamy paste. I make sure to wear gloves and do the mixing in a well-ventilated area.
Before I slather the bleach on my head, I'm careful to wear a shirt that will be sacrificed and use a towel that will be destroyed. Once I'm in full protective gear, I section my hair. If your hair is longer, then I would start with four sections and steadily tackle each (starting from the back). I apply the bleach from midlengths to ends, then do my roots last (as not to get hot roots).
Hot roots means your roots are lighter than your ends, which makes your new hair colour look uneven. This happens because our scalp is warm, and when the warmth mixes with bleach, it speeds up the developing process. For me, I keep my hair very short, so I just slather it all over my head as quickly as possible. Once my bleach is all set, I'll cover my head with a plastic cap and leave it on for 20 minutes.
After 20 minutes, I check my hair and see how many levels it has lifted. If I'm going brunette, then I'll aim for a yellow or yellow-orange at minimum (level 6-7); if I'm going blonde, then I aim for a light yellow (level 8-9). If I were to do a painterly colour, then I'd try to get my hair to a very pale yellow (level 9-10) so the colour result is as vibrant as possible. If, after 20 minutes, my hair is still very orange, then I check it every 10 minutes until I've achieved a workable base colour — DON'T LEAVE BLEACH ON YOUR SCALP FOR MORE THAN 45 MINUTES!
Once I've achieved my perfect base, I rinse my hair with lukewarm water and a purple shampoo (for yellow tone) or blue shampoo (for yellow-orange tone).