Forty minutes is the number that runs this service. A natural level 7 needs two levels to reach a pale-yellow 9, and a foil on 20 vol gets there in roughly 40 minutes, 60 at the outside. That number picks the developer and sets the checks.
Is 20 volume enough to highlight a level 7 to a 9?
Yes. Two levels on hair this light reaches pale yellow inside a foil.
A natural medium blonde hides yellow-orange, the strongest warmth on the chart, and two levels up sits the pale yellow of a 9. The 6% bottle is the foil default, 30 for coarse pieces a 20 cannot move, and more colorists forbid 40 in foils than use it. One part powder to two of developer, some tubs three, bond builder at its own dose, weighed into small bowls that puff as they stand.
Thin weaves, a slice at the face, sideburns foiled
Sections go thin enough to read print through, since chunky pieces lift warm and slow. Weave the interior, slice what should pop, pack the finest packets along the hairline. Sideburns get their own, even at three strands, and natural hair drops out between foils. Hold the section out, foil tight to the scalp. Start the lightener a finger under the fold, since head warmth puffs it and anything past the edge stripes the hair outside. Coat both faces or a missed patch shows as a pale dot, then feather the top.
Open the first foil at 20, pull the finished ones at 40
One timer starts when the last packet is folded. Open the first foil placed at 25 minutes, then every 10. At 20 a 7 is usually yellow with orange under it, an 8, and pulled there it stays yellow under any 9 toner. At 40 the strand is pale yellow, orange gone, the 9. A wet towel stops those packets while the back runs toward 60, and each is read dry, since wet hair looks a level darker.
Why do the foils look yellow when they come out
Because lightener stops at yellow and then pale yellow. The white inside a packet is the product, and the rinse reads yellower than the foil looked. A strand with the orange gone is the 9, and the violet bowl makes it the blonde in the photo.
9V through the lengths, a 7N tapped at the root
Wash, condition, squeeze to damp. A demi 7N on the line’s low developer, tapped across the first inch for 3 to 5 minutes, softens the join where foil meets regrowth. Some run it 20 minutes as a shadow, some skip it, since the next retouch lifts through that deposit. Then the 9.2, a 9V, on 10 vol or a toning developer through the lengths, 5 to 20 minutes, off before gray.
Violet is the pigment for pale yellow.
Blue at a 9 has no orange to cancel and drifts green-gray within the week, as the pearl and violet bowls show.
How long can highlights go between appointments?
Six to ten weeks before the regrowth asks for foils, and the toner goes first, at four to eight.
| Visit | When | What goes on | What it leaves |
|---|---|---|---|
| Visit 1 | Day one | Foils on 20 vol, 45 to 60 minutes, 7N tap, 9V | A pale-yellow 9 toned cool, natural 7 between |
| Between | Weeks 1 to 6 | Purple shampoo weekly, a mask | Cool thinning each wash, regrowth showing |
| Visit 2 | 6 to 10 weeks | Lightener on regrowth only, ends out or on 10 vol | A matching root, the old packets still a 9 |
| Visit 3 | 4 to 8 weeks on | The 7N and 9V again, no lightener | Violet over the pale yellow again, level unchanged |
Paler than a 9 means a 10 from this base, booked as its own appointment.
Can purple shampoo replace the toner refresh
No. It maintains a toner already on the hair, a little violet each wash, holding the cool longer. It is used by some as their only toner on a part line. The rest call it weekly upkeep and book the bowl.
Regrowth only on the second visit
Lightener goes on the new growth and stops where the old blonde begins. Those ends are kicked out, or ride in the packet on the 3% bottle with a bond builder. Nothing above 20 touches hair foiled before, though some overlap there at 20 with a bond builder. The band comes from the top edge: a thick straight stroke prints a hard line, feathered peaks print none. Then both bowls again.
