The ink, not the base
A substrate certified to Blue Wool 6 tells you how the uncoloured material holds up. The print on it is a separate question, and on a printed wall it is the only one that matters visually.
Colour, light & rub fastness
Light fastness and rub fastness — reading the numbers on your spec sheet
A schedule asks for “light fastness: dry rubbing ≥ grade 4, wet rubbing ≥ grade 3”, and has just named two different things in one line. One is about fading in daylight, the other about colour coming off on a cloth, and they are measured on different scales. This page explains which number is which, what each one is worth, and what actually fades on a printed wall — which is not the thing the grade was issued for.
Send us your spec sheetThe schedule, the walls and the light they sit in — we come back on what fits.
- Blue Wool 1–8
- The light-fastness scale. Higher is better; interiors are often asked at 5–6
- Grey scale 1–5
- The rub-fastness scale. Dry ≥ 4 and wet ≥ 3 are the usual asks
- ISO 105-B02
- The light test — a xenon lamp, not a window
- The ink fades
- On a printed wall the grade belongs to the base; the colour is yours
Two different tests, written on the same line
We see this constantly, and on a live tender this month the row was headed “Light fastness” with rubbing values printed underneath it. Read what is being measured, not the heading.
| Property | Standard & scale | What it answers |
|---|---|---|
| Light fastness | ISO 105-B02 — a xenon arc lamp, graded 1–8 on the Blue Wool scale | How long before daylight visibly changes the colour. 1 fades almost at once; 8 is the most durable |
| Rub fastness (dry) | ISO 105-X12 — rubbing with a dry cloth, graded 1–5 on the grey scale | Whether colour comes off on a dry hand or cloth. Grade 4 is the usual minimum |
| Rub fastness (wet) | ISO 105-X12 — the same test with a wet cloth, graded 1–5 | Whether colour comes off when the wall is cleaned. Grade 3 is the usual minimum, and it is lower than dry for a reason |
| Colour change | ISO 105-A02 — the grey scale used to judge the result, 1–5 | The yardstick the laboratory reads the change against, not a test in itself |
If your sheet gives one number, check which scale it is on. A “grade 4” on the Blue Wool scale is poor light fastness; a “grade 4” on the grey scale is good rub fastness. The same word means opposite things one line apart.
What actually fades on a printed wall
The certificate is issued for the material. The colour on the wall is ink, and it behaves on its own terms.
Some colours go first
Magenta and yellow are typically the least stable, so reds, oranges, skin tones and greens shift before blacks and dark neutrals do. A wall can look as though it has gone cold or green long before anyone would call it faded.
Fading is only visible when it is uneven
A whole wall fading evenly is almost invisible. What people see is the difference — a lighter band under a window, a rectangle where a frame hung, a gradient across a reception wall. Specify by the worst-lit part of the wall, not the average.
Spotlights count too
Daylight is the usual culprit but not the only one. Halogen and close-mounted spots put real energy on a small area for twelve hours a day, and that shows as a bright patch on an otherwise unchanged wall.
Glass helps, it does not save you
Ordinary glazing removes some ultraviolet, and modern coated glass removes more, but visible light fades print as well. Behind glass is slower, not safe.
A laminate slows it
A clear laminate with a UV filter buys time and also protects the surface from cleaning. It is a delay, not a stop, and it is worth specifying where a wall is both sunlit and touched.
What a Blue Wool number is worth in practice
The Blue Wool scale is relative rather than a number of years: each step up is conventionally described as taking roughly twice as long to show the same visible change, under the same light. That is why a single grade cannot be translated into “this wall will last X years” — a 6 in a shaded corridor and a 6 on a south-facing atrium wall will not age alike. The useful conversation is not whether a wall fades but how long before anyone notices, and that depends on the light the wall actually sits in. Tell us where the wall is and how it is lit, and the answer becomes a real one.
What to send us for a specified wall
Send these and we will come back on what can be met, what cannot, and what the alternative is.
- The specification sheet or the WC schedule, exactly as the consultant issued it.
- Which fastness is required, and on which scale — light, dry rub, wet rub.
- Where each wall is, and how it is lit: daylight, spotlights, or neither.
- Whether the wall is behind glass, and whether the glazing is coated.
- Whether the artwork has large flat areas of red, orange or skin tone.
- Whether a protective laminate is allowed, or the finish must stay uncoated.
- Wall sizes measured on site, and the artwork for each code.
What we will not tell you
We do not publish a fastness grade for our printed walls, and we will not tell you a print does not fade. Everything printed fades eventually; a certificate on the base material does not change that, and the honest figure is how long before the change is visible in the light that wall actually sits in. Tell us the grade your schedule asks for, and where the wall is, and we will confirm in writing what is available for it before you order — including whether a laminate is worth adding, and where we think the artwork itself is the risk.
Questions we are asked
What is the Blue Wool scale?
The scale light fastness is graded on, from 1 to 8, under ISO 105-B02. A sample is exposed to a xenon arc lamp alongside eight reference blues that fade at known rates, and the grade is the reference it matches. 1 fades almost immediately, 8 is the most durable, and interior wallcoverings are commonly asked at 5 or 6. Each step up is conventionally described as taking about twice as long to show the same change.
Our spec says “light fastness: dry rubbing ≥ grade 4”. What does that mean?
It means the row is mislabelled, and it happens often. Dry and wet rubbing are RUB fastness, measured under ISO 105-X12 on a grey scale of 1 to 5 — whether the colour comes off on a cloth. Light fastness is a different test, ISO 105-B02, on the 1 to 8 Blue Wool scale. If your sheet gives rubbing values under a light-fastness heading, it has specified rub fastness and left light fastness open.
Why is wet rub fastness allowed to be lower than dry?
Because water is a harder test. A damp cloth lifts colour that a dry one would not, so the same material always scores lower wet than dry. That is why specifications ask for dry ≥ 4 and wet ≥ 3 rather than the same number twice, and a supplier quoting one figure for both has probably quoted the dry one.
Does a fire or durability certificate cover fading?
No. Light fastness is a separate property with its own test and its own scale, and a material can hold a fire classification, a Type II durability grade and still fade quickly. If fading matters on your project it has to be specified on its own line.
Will a print fade behind glass?
More slowly, not never. Ordinary glazing removes some ultraviolet and modern coated glass removes more, but visible light fades print too. A wall behind glass in a sunlit atrium is still a sunlit wall; it simply takes longer to show.
Which colours fade first?
Magenta and yellow are typically the least stable, so reds, oranges, greens and skin tones shift before blacks and dark neutrals. A large flat area of one of those colours is where it shows first — which is why the artwork itself is sometimes the risk rather than the material.
Does a laminate stop a wall from fading?
It slows it. A clear laminate with a UV filter buys time and protects the surface from cleaning at the same time, which makes it worth specifying where a wall is both sunlit and touched. It is a delay rather than a stop, and any supplier who calls it permanent protection is overselling it.
Our schedule only asks for “good colour fastness”. Is that enough to quote?
It is enough to start, not to finish. We would need to know which fastness — light, dry rub or wet rub — on which scale and to what grade, where each wall sits and how it is lit, whether it is behind glass, and whether a laminate is allowed. Send the schedule as the consultant issued it and we will come back with the questions that are actually missing.
Related
Fire-rated wallcovering
B1, Class A and B-s1,d0 — what each one means and which your schedule asks for
Type II commercial grade
Scrubbable, washable and what actually wears a corridor wall out
Waterproof & moisture-resistant
Bathrooms, lobbies and why Gulf walls fail from behind
Antibacterial wallcovering
ISO 22196, hospitals and what a treatment may lawfully claim
Low emission & environmental
Low VOC, formaldehyde, phthalate-free and what a rating system wants to see
Custom wallpaper & wall murals
Sizes, finishes, how a wall is printed and installed
Reviewed 2026-10-03