Colour Fastness and What It Tells You — The Science Behind Whether a Ribbon Keeps Its Colour
Colour Fastness and What It Tells You — The Science Behind Whether a Ribbon Keeps Its Colour
Colour fastness is one of those technical terms that appears on test reports and specification sheets without much explanation of what it actually involves — why some ribbons hold their colour reliably across conditions and others bleed at the first hint of moisture or rub their dye onto everything they touch. Understanding what drives colour fastness, rather than just reading the grade, helps you ask better questions of suppliers and make better specification decisions for your packaging programme.
What Colour Fastness Actually Measures
Colour fastness is not a single property — it is a family of related properties, each measuring resistance to a specific stress that might cause a dye to move, change, or transfer. The most common tests in the ribbon industry assess fastness to washing, to rubbing, and to light. Each of these tests exposes a dyed sample to a defined stress and then measures the result using a standardised grey scale or blue scale.
The grey scale used for most colour fastness ratings runs from grade 1 (severe colour change or staining) to grade 5 (no change). The rating is determined by a trained assessor comparing the tested sample to reference standard cards — grey scale cards for colour change and staining, blue scale cards for light fastness. This comparative rating system is why colour fastness results are described as grades rather than measurements: the assessment is fundamentally visual and comparative rather than instrumental.
Why Different Dye Classes Perform Differently
The dye chemistry determines the baseline fastness ceiling for any given combination of dye and fibre. In polyester ribbon — by far the most common construction in decorative packaging ribbon — the dyes used are disperse dyes, which work by diffusing into the polyester polymer structure under heat and pressure during the dyeing process. When done correctly, the dye molecules are trapped within the polymer matrix and require considerable energy to move out of it. This is why polyester ribbon generally has good wash fastness and reasonable light fastness — the dye is physically embedded in the fibre, not sitting on the surface.
Nylon ribbon uses a different dye chemistry — acid dyes, which form ionic bonds with the nylon polymer. The fastness of acid-dyed nylon is generally slightly lower than disperse-dyed polyester for washing and rubbing, and nylon is more sensitive to pH — exposure to acidic or alkaline environments can affect the bond between dye and fibre over time.
The practical implication: if your programme includes both polyester and nylon ribbon in the same colour, the two may perform differently in fastness tests even if the colour looks identical. Specifying consistent fibre type across your programme eliminates this variable.
The Role of Dyeing Conditions in Fastness Performance
Even within the same dye class and fibre type, fastness performance varies significantly depending on how the dyeing was carried out. The key variables are temperature, pressure, time, and the ratio of dye to auxiliary chemicals (carriers, levelling agents, fixing agents). An under-dyed batch — one where the dye did not fully migrate into the fibre — will show lower fastness than a correctly dyed batch in the same colour, because the unfixed dye sitting on the fibre surface is easily removed by washing or rubbing.
This is one reason why colour fastness test results from a factory's standard production can be different from those produced on a specific controlled batch. A low fastness result is sometimes a process control issue rather than a dye chemistry issue — the same colour, dyed correctly, would achieve a higher grade. Factories with mature quality systems test colour fastness at the dye lot level rather than relying on historical results from similar colours.
What Dark Colours Reveal About the Limits of Fastness
Deep, saturated colours present the greatest fastness challenge in ribbon production. Navy, deep red, black, and dark forest green all require high dye loadings to achieve their depth. High dye loading means more dye molecules in and around the fibre — and more dye means a larger reservoir of potentially transferable colourant. Even when the dyeing is well-executed and the dye that has been correctly fixed is very fast, the presence of additional surface or near-surface dye brings rubbing fastness down.
This is a fundamental limit, not a quality failure. Grade 3–4 dry rubbing fastness in a deep navy or black ribbon is the realistic upper range for most production processes. Grade 4–5 dry rubbing in a pale blush or ivory is straightforward to achieve. The specification implication: apply more rigorous fastness standards to pale and mid-tone colours, and accept that deep saturated colours operate at a slightly lower ceiling, with the practical risk managed through application design rather than specification escalation.
Frequently Asked Questions
Why does some ribbon leave colour on my hands when I tie bows with it?
This is a rubbing fastness issue — the dye is transferring under the friction and moisture of hand contact. It typically indicates either a deep colour with inherently limited rubbing fastness, an under-dyed batch where surface dye was not fully removed in the after-treatment process, or a combination of both. In most cases it is manageable by washing the ribbon before use or by wearing gloves in high-volume bow-making, but persistent marking suggests a quality issue worth raising with the supplier. Contact msdribbon.com if you are experiencing colour transfer from ribbon in our range — we will investigate the specific batch.
Does ribbon colour fastness change over time in storage?
Colour fastness to light (light fastness) is the most time-sensitive fastness property — ribbon stored near windows or under bright display lighting will fade over time, with the rate depending on the dye class, depth of colour, and UV exposure. Fastness to washing and rubbing does not typically change significantly with normal storage time. For display applications where ribbon will be exposed to light for weeks or months, specify a minimum light fastness grade (typically 4+ on the ISO 105-B02 blue scale) and store stock ribbon away from UV exposure between use. Contact msdribbon.com to discuss light fastness specifications for display ribbon applications.
Is there a meaningful difference in colour fastness between recycled polyester ribbon and standard polyester ribbon?
For disperse-dyed polyester, the fastness performance of recycled polyester (rPET) fibre is broadly comparable to virgin polyester — the dye behaviour is determined by the polymer structure, which is essentially the same in both. The main variable is fibre consistency: recycled fibre has more batch-to-batch variation in polymer molecular weight and surface characteristics, which can introduce more variation in dye uptake and therefore in fastness results. Well-controlled rPET from certified sources is commercially available and performs consistently. Contact msdribbon.com to discuss our recycled polyester ribbon range and the colour fastness testing we conduct on it.
How is the grey scale used to grade colour fastness assessed in practice?
The grey scale is a physical reference card containing pairs of grey chips, each pair representing a specific grade of colour difference from 1 to 5 (with half-grade increments in some standards). The assessor places the tested sample and the untreated reference side by side, then identifies which grey scale pair most closely matches the difference between them. The assessment is done under standardised lighting (typically D65 daylight standard) to eliminate the effect of different light sources on the visual judgement. Multiple assessors sometimes grade the same sample independently to reduce subjectivity. Contact msdribbon.com for a copy of our test methodology and the grey scale standard we reference.
Can a ribbon pass a colour fastness test and still bleed in a specific packaging application?
Yes — test standards are generalised and may not replicate your exact conditions. A ribbon that passes a standard ISO 105-C06 wash test (standardised temperature, detergent, time) may still bleed when wrapped tightly against a coated paper surface in humid conditions, because the combination of sustained pressure, moisture, and a chemically different surface is not what the standard test replicates. If your application is unusual — ribbon in direct contact with food, wet environments, or chemically active surfaces — application-specific testing is more informative than standard test results. Contact msdribbon.com to discuss bespoke test conditions for atypical applications.
