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Home / News / Industry News / Colours Are Vivid at Printing — Why Do They Fade After Long-Term Storage?
Industry News
Packaging Inks · Label Printing · Flexible Packaging · Paper Printing
In packaging inks, label printing, flexible packaging, and paper printing, a consistent pattern appears: colours are vivid and saturated immediately after printing, all inspections meet requirements — but after a period of storage, the colour gradually becomes lighter, duller, and sometimes noticeably faded.
In most cases, this is not caused by the printing process. It results from the progressive effects of light, temperature, humidity, and ink system stability on colour over long-term storage.
Seven Factors That Drive Post-Storage Fading
1
Good Initial Colour ≠ Good Long-Term Colour Retention
When a product has just been printed: colour is vivid and saturated, gloss is uniform, and appearance meets requirements. These characteristics only indicate that the ink's initial colour expression is good — they cannot fully represent long-term weathering and colour retention performance. Vivid colour at printing does not mean fading will not occur during storage.
2
Light Exposure Accelerates Pigment Ageing
During storage or use: UV rays continuously act, visible light has a long-term effect, and photo-oxidation reactions occur continuously. Some pigments or dyes gradually undergo structural changes, causing colour to lighten and lose gloss.
3
Ambient Temperature and Humidity Affect Colour Stability
During long-term storage: high temperature accelerates the ageing process, humid conditions can affect the ink structure, and repeated temperature and humidity fluctuations reduce colour stability. If storage conditions are inadequate, fading may be more pronounced.
4
Ink System Stability Determines Long-Term Durability
Ink needs not only good printing performance but also long-term stability. If the system has insufficient pigment dispersion stability, weak resin ageing resistance, or poor compatibility between components — colour retention capability may progressively decline over time.
5
Substrate Also Affects Fading Rate
Different printing substrates provide different levels of protection for the ink. Plastic film, paper, metal packaging, and composite materials all have different barrier capabilities against light, moisture, and oxygen — which also affects the ink's long-term colour retention performance.
6
The Longer the Storage Time, the More Clearly Problems Appear
In the early period after a product leaves the factory: colour remains stable, appearance shows no obvious change. As storage time increases: light acts continuously, the environment changes continuously, and the ink ages gradually — colour change becomes more and more apparent.
7
Why Delivery Inspection Shows No Problems
Because when printing has just been completed: the ink is in its freshest state, the ageing process has not yet begun, and long-term storage effects have not yet been reflected. After months or more of storage: the colorant gradually ages, resin performance changes, and colour retention gradually declines — latent problems slowly become apparent.
Summary
Vivid initial colour but fading after long-term storage is fundamentally the combined result of light exposure, environmental factors, ink system stability, and material weathering performance.
Initial colour quality ≠ long-term colour retention
UV accelerates pigment ageing
Temperature and humidity variation affects stability
Ink system determines long-term weathering
Substrate affects colour protection
Longer storage = more pronounced fading
When analysing ink fading problems, in addition to focusing on the printing process, a comprehensive assessment of pigment light fastness, resin system, additive matching, substrate, and storage environment is needed to improve the product's long-term colour retention.
Frequently Asked Questions
Is fading primarily caused by the pigment or the resin binder?
Both contribute. The pigment's inherent light fastness — measured by the Blue Wool Scale or similar standards — determines how resistant its chromophore structure is to photodegradation. The resin binder affects how well the pigment is protected from environmental factors and how it is distributed within the ink film. A light-fast pigment in a poorly stabilised binder will still fade under sustained UV and heat exposure.
Does lamination or coating over the print improve long-term colour retention?
Yes — lamination, UV varnish, or overprint coatings add a protective barrier that reduces the rate at which UV, moisture, and oxygen reach the ink layer. The effectiveness depends on the barrier properties of the specific laminate or coating and whether it is UV-absorbing. This is why laminated packaging typically shows better long-term colour stability than unlaminated equivalents.
