Short answer: A hair-colour shade number is meaningful only with its brand and product line. A chart can identify the manufacturer’s shade family and instructions, but it cannot predict the exact result on hair with an unknown starting colour, previous colour history, porosity or grey percentage. Developer strength, mix ratio and grey-coverage guidance also belong to the named formula; do not transfer them from another brand or line.
Evidence scope: This guide compares published Wella Professionals material for two Wella colour lines as an example. It is not an independent colour test, a recommendation for a particular client, or a universal formula for salon work.
What a shade chart can tell you
A brand chart helps locate a shade in that brand’s system: level, tone family and product range. It does not establish that a shade code such as 7/0 or 7/75 means the same thing in a different manufacturer’s chart. Nor does a printed swatch reproduce every starting base, lighting condition, hair history or application method.
Before comparing two chart entries, record the exact brand, line, shade code, country-market packaging and chart date. A product name may be reused across markets while instructions or available shades differ. If the chart’s market or revision is unclear, consult the current manufacturer page or technical guide for that product.
Manufacturer guidance is formula-specific
Wella’s Koleston Perfect material gives separate mixing instructions for different shade groups. The core Pure Naturals, Rich Naturals, Vibrant Reds and Deep Browns guidance uses a 1:1 colour-to-developer ratio, while Special Blonde uses 1:2. The same guide assigns developer strengths to stated lift goals and gives separate grey-hair mixing examples. Those numbers describe the named Wella line and its instructions; they are not a conversion table for another permanent colour.
| Published Wella line guidance | What the document says | What it does not authorize |
|---|---|---|
| Koleston Perfect | The usage booklet gives Pure Naturals additions by stated white-hair ranges: 1/3 for 30–50% and 1/2 for 50–100%, alongside its own ratio and developer directions. | It does not make the same ratios valid for another Wella line, another brand or every colour service. |
| Illumina Color | Its technical folder says up to 70% grey/white hair may use the shade alone; above 70%, it advises a 1:1 mix with a neutral base and says not to mix with Koleston Perfect. | It shows why a coverage rule from one colour family should not be copied into another, even within the same manufacturer. |
Wella’s own guidance therefore gives different grey-coverage thresholds and mixing instructions across these two lines. That is a concrete reason to identify the formula and the document version before interpreting a “grey coverage” claim.
Grey percentage is an input, not a promised outcome
“Up to 100% grey coverage” is a manufacturer’s stated capability for a named product under its instructions; it is not a guarantee that every shade, hair history and application will produce identical coverage. The technical materials distinguish ranges of visible grey and direct users to particular bases or ratios. They do not measure a specific client’s hair or establish a result from a photograph.
For a consultation record, keep the client’s requested outcome, starting level and tone, visible grey distribution, previously applied colour, target shade code, product line, developer and mixing instructions as separate fields. If any input is uncertain, the colourist should explain that the result cannot be read directly from the swatch. We have not observed or interviewed a salon or client for this article.
How to compare two shade-chart claims
- Check the complete product name. “Permanent”, “demi-permanent” and “toner” do not by themselves identify a formula or its coverage claim.
- Keep the brand and line attached to the code. Write the code with the full product line and market, not as an unlabelled number.
- Open the matching technical guide. Confirm developer type and strength, ratio, timing, shade-family exceptions and grey guidance in the manufacturer document for that line.
- Separate a shade match from a coverage claim. A swatch comparison addresses tone/depth; a coverage statement has its own product-specific conditions.
- Check safety instructions independently. Colour selection does not replace allergy-alert or application directions. Wella’s Koleston guide advises an allergy alert test 48 hours before each colouration and says a reduced risk is not zero risk; use the latest package instructions for the product actually selected.
- Do not mix instructions across lines. If an instruction is missing from the chart, ask the manufacturer or use its current professional guide rather than improvising a ratio or processing time.
Quick comparison template
When checking a shade recommendation, record: brand; exact colour line; shade code and name; country-market chart and revision; starting level/tone; grey estimate and distribution; product-specific developer; mixing ratio and time; and the source URL. Mark any unknown field as unknown. This makes advice easier to review without presenting a catalogue swatch as a guaranteed result.
Primary manufacturer sources
- Wella Professionals Koleston Perfect shade chart and usage guidance — named-line mixing, lift and grey-hair examples.
- Wella Professionals Koleston Perfect usage booklet — product-specific application, ratios and safety instructions.
- Wella Professionals Illumina Color technical folder — separate line-specific grey guidance and compatibility note.
- Wella Professionals: covering grey on dark hair — consumer explanation of different Wella product-line options; promotional claims are attributed to Wella.
Sources checked 2 October 2026. Manufacturer documents are product guidance, not independent tests. Shade charts and formulas may change by market or revision; confirm the current product insert before use.
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