- Lightfastness describes how colours change exposed to light.
- It is just as important as abrasion resistance, ease of care and fire protection.
- Key factors include lighting conditions, colour tone, dyeing method and fibre.
- The blue wool scale (1–8) serves as a common guide.
- ‘Fading’ in sunlight is often predictable.
The Sparkasse Rattenberg bank is a place where historical architecture meets contemporary use. Stone, beams, existing structures and, at the same time, consulting, waiting areas, aisles and interactions.
Properties like these demonstrate the requirements that fabrics must meet. They should not be susceptible to damage when many people use them every day. They should be easy to clean, easy to handle and visually reliable, even when light is an issue in the room.
And anyone who has experienced a sofa by the window ‘fading’ after a while will know this phenomenon. Colours change, sometimes gradually, sometimes significantly. Not overnight, but more like a subtle shift that you don’t notice until you move a cushion.
This is where the lightfastness of fabrics becomes important.
Key Facts
Home & Contract Fabrics
If we're talking about interior fabrics, there are a few things to keep in mind:
- Abrasion and everyday use
- Pilling and appearance: ensuring that textures do not look ‘tired’ too quickly
- Cleaning and care: stains, disinfection, care intervals
- Fire protection and safety requirements: depending on use and specifications
- Response to light: ensuring that colour concepts do not drift unintentionally
Requirements that should be considered early on when discussing windows, lighting and colour concepts.
What does "lightfastness" mean?
Lightfastness is not a feeling.
It is a verifiable value. Often, this value is shown on data sheets as a scale, frequently as the ‘blue wool scale’ ranging from 1 to 8.
Lightfastness describes how significantly a colour can change when exposed to light. This primarily refers to the fading or changing of colour tones when daylight, UV rays and artificial light impact a material over a longer period of time.
Understanding values
The blue wool scale ranges from 1 (very low resistance) to 8 (very high resistance).
- The scale helps with comparison.
- It provides information about the resistance of a colour to light.
- It is a guide.
- The specific application determines how relevant a value is.
The difference between two levels is usually clearly visible in practice. Especially in window areas or with long-term lighting, a small number in the data sheet can have a big impact later on.
Sun, spotlights, table lamps
Light is not just ‘bright’ – there are significant differences:
- Direct daylight: high intensity, especially with large glass surfaces
- Diffused light: less aggressive, but constantly present UV components: often the cause of colour changes, depending on glass type and shading
- Permanent artificial lighting: relevant in commercial properties.
Key point: Different light qualities come together in the real world. Therefore, lightfastness must be considered as part of the overall concept rather than on its own.
Why do fabrics fade in the sun?
Colours react differently.
Light, especially light containing UV rays, can alter dyes and pigments. Some colour systems react quickly, others more slowly. The result is not always classic fading. Sometimes a colour tone shifts slightly. Sometimes it loses depth or a surface suddenly appears flatter.
Fibres, colours, dyes
It is tempting to categorise lightfastness by material. However, lightfastness is determined by a combination of fibre type, colour tone, dyeing method, finish and location in the room.
The same fibre can show big differences depending on how it's dyed and what colour it is. Even a fabric that's ‘suitable for commercial use’ can surprise you when it's in the wrong spot and if the light and colour don't work well together.
A comparison of materials
Wool
Wool can reach solid lightfastness values indoors, especially if it is well dyed and has suitable colour tones. In addition, it offers practical advantages. For areas with intense light exposure, check the value in the data sheet, consider the colour tone and determine the position in the room.
Linen and cotton
Both can be sensitive, depending on their dyeing and colour. Especially clear colours show changes faster than muted tones. This is an good reason for smart placement: choose indirect light, carefully select colour families, or opt for a patina to develop over time.
Synthetic fibres
Some synthetic fibres come with colour that's built into the fibres. This can be a good thing in bright areas because it means the colour won't fade as quickly. These fabrics have a different feel compared to natural fibres. In busy areas, this is often perfectly fine.
Velour, chenille, microfibre
Depending on the pile of these fabrics, light and viewing angle alter colour perception. Small colour changes are less apparent than in smooth fabrics. Care, abrasion and lightfastness are three separate issues. Data sheets instead of gut feeling!
High-performance fabrics
Technical fabrics designed for high light exposure are appearing more and more often in interiors. They are particularly popular as a solution for conservatories, large glass surfaces or workspaces with lots of light.
What level of lightfastness is "good enough"?
There is no single figure that fits all rooms without knowing the context.
It makes sense to use a guideline combined with simple reasoning:
- Lots of direct sunlight or very bright window areas: generally plan for higher values.
- Mixed light, less direct exposure: medium values may be sufficient.
- Sensitive colours (very dark, very intense, very clear): take a closer look.
- Areas with long-term use: opt for a more conservative approach.
If a project is particularly challenging, it is worth taking an extra step. View samples in real light. Not just in the showroom, not just in the evening light.
Four questions
on fabric selection
The Hands-on part
- Where is the surface located in the room?
At the windows, in a niche, at an interior wall or passageway - What is the light profile like?
Lots of sun, lots of scattered light, long exposure duration - How complex is the colour tone?
Deep blue, rich green, warm red, light pastels - How long should the solution remain before being replaced?
Short-term versus long-term, private versus commercial
These questions may seem trivial, but that is precisely why they are so useful. They shift the focus from technical aspects to planning.
Sparkasse Rattenberg
Lightfastness was just as important in this project as cleaning properties, durability and appearance. It was considered a design parameter and a guideline for fabric selection.
The same applies at home, only on a smaller scale: if a sofa is exposed to sunlight every day, this will affect its colour. If you take this into account early on, you can feel more relaxed about your decisions. Often, the result will look better too, because the material, colour and positioning have been considered together.
CONCLUSION
Lightfastness is not specialized knowledge for laboratories. It is a tool for making good decisions. In commercial spaces, in private rooms, wherever light plays a major role.
We therefore recommend a clear routine: understand the lighting situation, take the colour tone seriously, check the value, view samples in real light. With expertise.
Teresa Gruber
BSc.; Interior Design
With her keen eye for textures, colours and the delicate balance of functionality and design, she contributes to interior design in a wide variety of projects. In her articles, she shares insights from her professional experience, inspiration from the world of interior design and tips for thoughtful planning.
‘For me, good interior design begins where materials have a very subtle effect and shape the ambience.’
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