The third and final element of our “Decoding Your Warranty” blog series covers paint chalking. As with fading, chalking is an expected occurrence with any paint system that is subjected to outdoor exposure, and while it may be preferable to other issues such as cracking or peeling, it is still important to the metal roofing industry and its customers. As a result, similar questions should be asked about how this is addressed in paint system warranties to ensure chalking isn’t the cause of premature damage to your metal roof system.

On the left, the resin takes on a white, chalky, appearance that compromises the paint's true color.
On the left, the resin takes on a white, chalky, appearance that compromises the paint’s true color.

What is paint chalking?

Also referred to as “powdering”, chalking happens when the resin (binder) of the paint system is compromised. The resin is the substance that holds the paint pigment together. It also ensures the color is evenly distributed and provides glossiness, durability and flexibility. In addition, resin has the very important job of adhering the pigment to the metal surface it’s applied to and protecting the finish against damage.

When the resin at the surface of the paint finish deteriorates, most often as a result of exposure to ultraviolet (UV) rays, the embedded pigment particles lose their adhesion to the paint film (resulting in color fading) and the resin particles take on a white (chalky) appearance that is easy to wipe off of the surface. In addition, chalking can erode the film resulting in a loss of substrate protection and run down onto the underlying structure, further degrading the appearance of your structure.

How can you protect against paint chalking?

Climates that are exposed to more intense UV rays for longer periods of time will experience chalking sooner as the environment plays a big role in how painted metal will perform. While you may not be able to control how much UV or moisture exposure your roof gets, you can choose a paint system that is not over-thinned or over-spread and that uses high quality components. ABC’s Signature® 200 system incorporates a 30 percent SMP Resin—one of the strongest in the marketplace—to help reduce the amount of chalking experienced.

Similar to the fading section of the warranty, paint system warranties allow for an acceptable amount of chalking. Chalking is measured in accordance with the standard procedures as defined by the “Standard Methods of Evaluating Degree of Chalking of Exterior Paints”, ASTM D4214. ABC guarantees the level of chalk on vertical panel applications will not chalk in excess of a numerical rating of eight (the higher the numerical rating, the better) for 30 years for our Premium paint system colors and 25 years for our Select40 paint system colors. For non-vertical panel applications, ABC guarantees a rating of 6 for 30 years for our Premium paint system and 25 years for our Select40 paint system. Consumers should be aware of these numbers, and expect them to be expressed in sample warranties.

Check out ABC’s metal color resources and warranty information to learn more!


Missed parts one and two of the “Decoding Your Warranty” blog series? Start reading now!

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