If you are standing in the beauty supply and unsure, buy the 20 volume cream. That is the answer most colorists give, and it is the bottle that goes into the bowl for a root retouch, gray coverage, a level or two of lift and lightener on the regrowth. Six percent hydrogen peroxide. It lifts one to two levels on natural hair with permanent color in 35 to 45 minutes, it opens white hair far enough to take pigment, and it is as strong as most colorists will put on skin under bleach. 10 volume is for deposit and toning, 30 and 40 are for hair that has to go further, off the scalp, and nearly everything in between is 20.
A few things get checked before anything is mixed, because 20 is gentle on most scalps and the exceptions hurt. Look at the skin along the parting. A scalp that was scrubbed hard that morning, scratched with a comb or carrying a patch of psoriasis behind the ear will sting inside ten minutes under 20 vol color and can blister under lightener, and some colorists tell clients to leave their hair unwashed for a day or two before a scalp bleach so the natural oil sits between the skin and the mix. Gloves on before the bottle is opened, a plastic or glass bowl, and cream developer for anything going on near skin, because cream stays where it is put. No dryer over it unless the brand’s directions allow heat.
What two levels looks like
A natural level 4 on 20 vol permanent for 35 minutes is a 6, and a 5 is a 7. Two levels on healthy, uncolored hair. The level chart shows which pigment surfaces at each step, orange at 6 and yellow-orange at 7, so the lift lands warm and the shade in the tube has to carry enough ash to sit on it.
Two heads stop 20 short. Coarse, resistant hair takes one level in the brand’s time and then sits, and that second level wants 30. Previously colored lengths do not move at all on any developer, because the peroxide has no natural pigment left to work on there, and lightening old tint is a bleach or remover job. Three levels is the other stall. A 4 that wants to be a 7 sits at a warm 6, because by 45 minutes the peroxide has done what it is going to do and the last level was never in the bottle. That is 30 vol from the start, or two visits on 20 six weeks apart, and the processing time calculator will not give you a minute count past the brand’s maximum for that reason.
Natural uncolored hair, permanent color unless the row says lightener.
| From | To | On 20 vol | Minutes |
|---|---|---|---|
| Level 4, medium brown | Level 6, dark blonde | Two levels, lands warm, ash shade in the bowl or a toner after | 35, 45 on resistant hair |
| Level 5, light brown | Level 7, medium blonde | Two levels, stalls yellow-orange without a blue-violet shade in the mix | 35 to 45 |
| Level 6, dark blonde | Level 8, light blonde | Two levels on fine or medium hair, coarse hair stops at a 7 and wants 30 | 45 |
| Level 7, part white | Level 7, gray coverage | Deposit at the same level, full coverage with an N shade | 35, 45 on resistant white |
| Level 4 | Level 7 | Stalls at a warm 6, three levels is 30 vol or two visits | 45 and no further |
| Regrowth, any level | Lightener on the scalp | Clean lift with body heat helping, rinse at the level | Check at 15, then every 10 |
Any gray at all, and it is 20
Any gray in the head and the developer is 20. Coverage is deposit, and 20 is the strength that opens the tight, wiry white cuticle far enough for pigment to lock in without lifting the pigmented hair around it. Resistant white wants the full 45 minutes and more natural (N) shade in the bowl, and it wants saturating, because a thin coat over wiry hair is where the sparkle at the temples comes from. Going up to 30 to force it does the opposite. The pigmented hair lifts a level, the color goes in thinner, and the white reads sheer and fades in three weeks. Going down to 10 because the target is darker anyway blends the gray, and a blend slides off within a few washes.
Four things people say about 20 volume
“40 will get me lighter than 20.” With lightener it gets you to the same place faster. Same powder, same pale yellow, more heat and less time to catch it in. With permanent color the tube caps the lift at two levels on 20 and three on 30, so a higher volume buys one level, and never more than the tube allows.
“More volume covers gray better.” Higher volume trades deposit for lift, and coverage is deposit. A 6N on 30 over a half-white head lands sheer and warm and is gone in three weeks.
“20 is safe on any scalp.” Safer than anything above it, which is a different claim. A scratched scalp, a hard shampoo that morning, a patch of eczema, and 6 percent stings within ten minutes.
“Mixing 20 and 40 makes 30.” True. Developer is peroxide in water, and mixing two strengths is a dilution, so equal parts by weight sit at 9 percent. The arithmetic for unequal parts is on the volume chart, and most colorists skip it and buy the 30. If the box gives ounces and your scale reads grams, the developer mix calculator swaps between them.
Lightener on the scalp, low and slow
Nothing over 20 goes on the scalp with lightener in most salons, and a good number of colorists call 20 their ceiling for a whole-head lift, two rounds a few days apart on 20 instead of one hot pass. The reason is heat. The scalp sits at body temperature and radiates, so bleach on regrowth runs faster than the same bleach in a foil an inch away, and 20 on the scalp lifts close to what 30 does off it. With lightener the developer only sets the pace anyway. The lift is in the powder, which is why the tub says up to seven or nine levels and the developer bottle says nothing about levels at all.
Application order comes from the same heat. Start at the back, which lifts slowest, keep the mix half an inch off the scalp on the first pass and do the roots last, or the roots go pale while the lengths are still orange. Saturate. Most people at home do not use nearly enough and get spots for it. Check at 15 minutes and every 10 after, wipe a strand clean before you judge it, and rinse when the level is reached or the client says the word warm. Most colorists agree lightener is done inside 45 to 60 minutes and only dries out after that, though one or two will tell you it keeps eating until you rinse, and either way nobody leaves it and walks off.
