How to Fill Hair Before Going Darker
By the Formula Finder teamUpdated 6 min read
The short answer
Fill when the target is 3 or more levels darker than the lightened hair. Use a warm filler that puts back the pigment the target level is missing: gold for levels 7 to 9, gold with red at 5 and 6, red and warm brown at 4 and deeper.
On this page
Lightened hair turns muddy, green or hollow when it goes darker because the warm pigment that makes brown look like brown is gone. A filler puts that warmth back first, so the target shade has something to hold onto.
Why lightened hair goes muddy, green or hollow
Natural hair at every level carries warm underlying pigment. The Matrix haircolor manual maps it level by level: red at level 4, red orange at 5, dark orange at 6, orange at 7, dark yellow at 8, yellow at 9 and pale yellow at 10. Lightener removes that pigment as it lifts. A highlight lifted to level 10 has only pale yellow left.
A level 6 dye is built to sit on hair that already holds level 6 warmth. Put it on pale yellow and three things go wrong:
- Green. Ash and many natural shades carry blue or green to control warmth. Blue over yellow reads green, and there is no orange left underneath to cancel it.
- Muddy. Without red and orange under the brown, the color has no richness. It reads flat, smoky or khaki.
- Hollow. Lightened hair is porous. It grabs dye fast and lets it go just as fast, so the color looks see-through and the warm part of the formula fades first, leaving the cool part behind.
Schwarzkopf Professional's IGORA Royal technical manual names the two problems directly: the hair is porous toward the ends, and the base is far too light to support the dark result. Its fix is to put the contributing pigments back into the hair before the target color goes on. That is filling. Matrix defines it the same way: depositing underlying pigment back into over-lightened hair.
If level numbers still feel shaky, start with how hair color levels work.
When you need a filler
Count the levels between the lightened hair and the target.
- 1 to 2 levels darker: no filler. The target formula carries enough warmth to cover a small gap, especially with a natural or gold reflect.
- 3 or more levels darker: fill. Wella Professionals sets the line at a target more than two levels darker than the starting level.
Grown-out highlights are a mixed canvas. The regrowth still has its natural pigment, and only the lightened pieces are missing warmth. Fill the lightened, porous sections only. The IGORA Royal manual says the same thing: pre-pigment the relevant areas, meaning the lighter and porous hair.
Choosing the filler tone by target level
The filler replaces what the target level would naturally contain. Look at the target level, not the starting level, and fill with the pigment that level is missing.
| Target level | Missing pigment | Filler tone direction |
|---|---|---|
| 9 | Yellow | Soft gold, mostly diluted with clear |
| 8 | Dark yellow | Gold, diluted with clear |
| 7 | Orange | Gold at full strength |
| 6 | Dark orange | Gold with some red |
| 5 | Red orange | Equal gold and red |
| 4 | Red | Red and warm brown with a little gold |
| 3 | Dark red | Red and warm brown |
| 2 | Red brown | Intense warm brown |
The missing pigment column follows the Matrix underlying pigment chart. The direction column follows one rule: the deeper the target, the more the filler moves from gold toward red and warm brown.
Fill warm even when the target is ash. The ash target neutralizes the extra warmth on top of the fill. Skipping the fill for an ash result is the fastest way to get green.
Wella Color Touch fill chart
Wella publishes a full fill chart for Color Touch, the brand's ammonia-free demi. Every fill mixes 1 part color to 2 parts Color Touch Emulsion 1.9% (6 volume). Wella calls the chart a guideline to adjust for porosity and the target shade.
| Target level | Fill formula |
|---|---|
| 9 | 1.5 oz 0/00 + 0.5 oz 9/3 |
| 8 | 1 oz 9/3 + 1 oz 0/00 |
| 7 | 2 oz 9/3 |
| 6 | 1.5 oz 9/3 + 1 oz 6/4 |
| 5 | 1 oz 9/3 + 1 oz 6/4 |
| 4 | 0.5 oz 9/3 + 0.5 oz 6/4 + 1 oz 6/77 |
| 3 | 1 oz 6/4 + 1 oz 6/77 |
| 2 | 2 oz 6/77 |
Read it as a pattern. 9/3 Very Light Blonde/Gold does the work at the light end. 6/4 Dark Blonde/Red brings in red from level 6 down. 6/77 Dark Blonde/Brown Intensive takes over at the deepest levels. 0/00 Clear dilutes the gold at levels 8 and 9 so the fill doesn't overshoot. More Wella charts are in the library, and if the slash codes are new to you, here is how to read a hair color chart.
One-step vs two-step filling
Both methods put warmth back before the target shade sets. The difference is whether you rinse in between.
Two-step: fill, rinse, then color
This is Wella's Color Touch method:
- Apply the fill to pre-shampooed, towel-dried hair and develop up to 20 minutes.
- Rinse until the water runs clear, then towel-dry.
- Apply the target shade, mixed 1:2 with 1.9% emulsion, and develop up to 20 minutes. Pick a warm, natural or cool reflect for the finish.
Two-step takes longer, but you see the filled canvas before the target goes on. Any section that grabbed too much or too little shows up at the bowl, not after the blow-dry. Use it for big jumps, blonde to brunette changes and very porous lengths.
One-step: fill, then color on top
The IGORA Royal technical manual runs pre-pigmentation without a rinse:
- Apply a semi-permanent shade to the lighter, porous areas on dry or towel-dried hair. Schwarzkopf uses semi-permanent products only for pre-pigmentation.
- Apply the permanent target color right on top of the pre-pigmented hair and develop 30 to 45 minutes.
- Choose the permanent shade 1 level lighter or the same level as the desired result, depending on hair condition, so the finish doesn't go too dark.
- When the end result is more than 2 levels darker, mix the permanent color 2 parts fashion shade to 1 part natural shade.
One-step saves a full rinse and dry, which makes it the practical choice for regrowth plus highlights in a single appointment.
Some lines build the fill into the color itself. Scruples makes its Shadow Lowlights gels and Hypnotic cremes with filler inside, so lowlights go on in a single step with no separate fill.
Which one to pick
- Going 3 to 4 levels darker on evenly lightened hair: one-step works.
- Going 5 or more levels darker, or filling very porous ends: two-step, so you can check the canvas.
- Placing lowlights through highlighted hair: a filler-infused lowlight product or a one-step fill on the lowlight sections only.
Formulating the target over the fill
Filled hair takes color more readily than the same level of natural hair, so pull the target formula back slightly. The Matrix manual says to formulate a darkening service at the same level or 1 level lighter than the desired result, layered over the fill. The IGORA Royal manual gives the same rule for its permanent shade.
Lightened hair doesn't need lift, so keep the developer low. Demi and deposit formulas on low volume do the job without opening the cuticle any further. If the volume choice is the part that trips you up, see developer volume explained.
Apply the filler and target to dry or towel-dried hair evenly, and keep the most porous ends for last if they grab fast. Fill only what was lightened. Natural regrowth gets the target formula alone.
Build the formula
Fill by the target level, warm toward gold for lighter targets and toward red and warm brown for deeper ones, then lay the target shade on top one level lighter or at level. Formula Finder builds formulas from real shade codes in your brand, starting from the client's inspo pic.
FAQ
Why did my brown turn green on bleached hair?
Bleached hair has only pale yellow left, and the blue in ash or natural brown reads green over yellow. A warm filler first puts back the orange and red that cancel the blue.
Do I need to fill hair going 2 levels darker?
Usually not. A gap of 1 to 2 levels is covered by the warmth already in the target formula, and fillers come in at 3 or more levels darker.
What color filler do I use to go from blonde to brown?
Pick it by the brown you are going to. A light brown at level 5 or 6 needs gold with red in the fill, and a dark brown at level 3 or 4 needs red with warm brown.
Do you rinse a filler before applying color?
It depends on the method. Wella's Color Touch method rinses the fill until the water runs clear before the target goes on, while the IGORA Royal manual applies the permanent color right on top of the semi-permanent pre-pigment.