Why Does Paint Fade?

Why Does Paint Fade?

Paint failure on external elements of a building can become unsightly and affect the overall appearance. The initial and subsequent coatings used to provide an identity to a building through colour and it also provides a protective layer to the underlying substrate. The resulting degradation of the coating can affect how potential customers and tenants view a building and this can have an impact on business. We look at the factors that contribute to the coatings life cycle and what can be done to prolong the life expectancy before re-coating is necessary. So why does paint fade?

Why does External Paint Fail?

The technical term for fading is photodegradation. A number of factors can affect the failure of a coating. These are:

  • Weather Conditions and UV light
  • Incorrect Paint type used previously
  • Incorrect preparation and application of paint.
  • Pollutants that attack the coating
  • Poor maintenance.
  • A combination of the above.

Certain colours fade faster than other with red colours tending to break down faster than blue for instance.

Why Does Paint Fade and Areas That Are Affected

Building materials that we regularly see affected by faded paint are:

  • Curtain Wall Sections
  • Metal Windows & Doors
  • Metal Cladding
  • Roller and Security Shutters
  • Signage & Fascia
  • Gutter and downpipes
  • Masonry

Faded paint on entrance

The direction at which the building is facing is a factor in the fading of the coated areas. Areas that have constant exposure to the sun will experience accelerated fading compared to the other elevations. Similarly, if an area is in complete shade, constant damp conditions can affect the coatings.

Chalking Paint

Paintwork on existing buildings can appear lighter in certain areas and this is often caused by the paint chalking.

What is Chalking?

Cladding showing chalking

Chalking is the term used when paint begins to fail and a white chalky like appearance appears from the paintwork and can often be wiped away. The chalking is most often caused by weathering. The binder in the paint is broken down by constant exposure to sun and damp conditions. Regardless of the paint system used on external building materials, it will eventually show some sign of chalking after a period of time when exposed to weathering.

To understand why chalking occurs we have to look at what paint is made up of. Paint is made up of a mixture of pigments. Colour particles are bonded together with a resin. As paint is applied to the underlying substrate and then dries, the clear resin is shown on the surface with the coloured pigments encapsulated beneath.

When UV rays and moisture attack the paintwork after a number of years the resin layer begins to fail and thins away. The result is that the pigments below become exposed and are no longer protected by the resin. The resin is easily wiped off and this is a typical sign of chalking. The chalking phase of paint failure is the ideal opportunity to carry out maintenance work to the affected areas. If left the next phase of the paint failure would be cracked and flaky paint finish which can result in rust.

As mentioned chalking would eventually occur on all coated surfaces (this is desirable as it provides an ideal surface for re-coating) but colour has an affect on how fast this can occur. Generally, Alykd paints chalk faster than acrylic latex coatings. Medium to heavy chalking will result in a lighter appearance of the of the paintwork. Extreme chalking will make adhesion of any subsequent coats difficult as there isn’t a sound coat to apply to. High-quality coatings that use quality binders tend to last longer before chalking is prevalent and although mild chalking may appear, they will last a number of years and maintain a sound surface that withstands weathering.

 

How To Prevent Premature Fading of Paintwork

  • Choose the correct coating system for the substrate and location. There are a wide variety of paint options available.
  • Ensure the correct preparatory work is carried out.
  • Ensure the correct application, following the manufacturer’s technical literature.
  • Regular maintenance according to the paint manufacturers guidelines.

How Vanda Coatings can help if areas have been affected by fading,

We can survey the affected areas and recommend a proposal for re-coating with a suitable system designed for the substrate. The coating systems we offer are commercial grade that are able to withstand UK weather conditions until the next maintenance cycle is due. Typical life to next maintenance is 8-13 years depending on the environmental conditions. Please contact us to discuss further.

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