Alkyd systems
Alkyd and solvent-based systems oxidise over time. Yellowing is particularly visible in shaded spots where UV doesn't "clean" the surface.
Why Does White Paint Turn Yellow?
Causes of discolouration and how to prevent it
What happens technically
White is the most common choice for apartment buildings - bright, clean, Mediterranean. However, in some cases yellowing or dulling is observed within a few years.
Three mechanisms trigger discolouration: UV radiation degrades the resin, film components oxidise, and pollutants accumulate on the surface.
Common causes of yellowing
Yellowing is not random. Four factors are responsible in most cases.
Low-quality resin
Budget products with poor UV resistance. The resin degrades faster and shifts the white tone.
Atmospheric pollution
Exhaust fumes, particles and airborne substances settle on the surface, creating a gradual tonal shift.
Moisture & microorganisms
In high-humidity areas, microbiological deposits can develop that alter both colour and film integrity.
Yellowing vs chalking: not the same
The distinction is critical for proper remediation. Yellowing is a colour tone change - you touch the surface and your hand stays clean.
Chalking is resin breakdown - your hand picks up white powder. Chalking means the resin has decomposed and requires cleaning and priming before repainting.
If the surface leaves powder on your hand, it isn't yellowing - it's chalking and needs a different treatment.
How to prevent yellowing
Four practical measures dramatically reduce discolouration risk.
① Right system
Choose 100% acrylic or silicone-based systems. Modern acrylics offer significantly better UV resistance compared to older formulations.
② Quality pigments
Use high-quality white pigments (TiO₂). Cheap pigments degrade faster and promote discolouration.
③ Proper preparation
Clean the substrate, remove loose old layers, apply primer. Painting over a dirty substrate accelerates deterioration.
④ Periodic cleaning
Washing the facade every 3–5 years removes pollutants before they "set". Prevention costs far less than premature repainting.
When repainting is necessary
If yellowing is uniform and purely aesthetic, a simple repaint is enough for renewal. No special preparation beyond basic cleaning is needed.
If it's accompanied by chalking, the process changes radically: pressure cleaning, stabilising primer, then the new application. Without cleaning, a new coat fails even faster.
Repainting a chalked surface without cleaning = accelerating the next failure.
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Paints for Building Facades
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