Paint system chalking and fading on metal panel systems are important considerations to be aware of and educated about. Know what questions to ask and what to look for before you buy.
When compared to other materials used in the roofing industry, like asphalt, tile, or cement, metal roofing has considerable advantages. In addition to lasting decades longer than other materials, metal panel systems have become even more affordable and practical for both commercial and residential uses. One of the most attractive characteristics is the variety of colors that metal offers, which is why having the option to choose from a variety of different paint colors and finishes is so important.
But how much do you know about how the color on a metal roof will change over time? Or, have you heard the terms “fading” or “chalking” and wondered how those might affect your roof?
Sheffield Metals is an industry leader in the distribution of metal coil and bare metal products used for roofing and wall systems. Before you make the decision to purchase that metal roof or wall system you’ve been looking at, we want to help familiarize you with how different paint systems will perform, especially in regards to chalking and fading, depending upon the elements they are exposed to.
In this article, we hope to give you a better understanding of:
If you’re purchasing a metal roof or already have, you might be asking yourself: Will my metal roof fade?
The answer is yes.
Fading on painted metal roofs occurs when substances like water, pollution, and chemicals in the atmosphere and specific environments react with the pigment of the paint. In other words, the pigment begins to break down, which causes the color change. This change usually lightens the color, but it has been known to darken or completely change specific colors. Also, it’s important to note that panels on the same structure may not even fade uniformly, as every portion is not always subject to the same elements.
No matter what type of pigment or resin that a manufacturer uses on a coil, nothing will preserve the color forever in an outdoor environment. As we discussed in our explanation of metal roof paint warranties, the best way to imagine what fading on metal will look like is to compare it to how a piece of clothing might fade its color over time. Even though the color fades because of regular wearing and washing, it doesn’t take away it from how well it wears, or in a metal panel’s case, it doesn’t take away from how well it protects your structure.
That being said, there are ways to prolong the life of the color on your roof, and it starts with being educated and informed about the factors that affect fading, the types of resins/how well they stand up to the elements, and how fading is actually measured.
The resins used in paint systems make all the difference when it comes to the longevity of the color on a metal coil or panel. While these names are very technical, think of these as “good, better, best” classifications to help you determine what resin will work best in your environment.
The standard for measuring the fade on a metal panel is determined using Hunter Lab’s Delta E (∆E) unit, according to ASTM International standard D-2244. The number that represents “E” in ∆E is the difference between a sample of the paint and the paint’s original color. For example, if a sample comes in at ∆3, it means the color has changed three Hunter Delta E units from the original. See the sample photo on the right for a visual of paint fading.
Paint system warranties cover fading up to a certain Hunter Delta E (∆E) unit during a specific time frame. For example, if you have a 30-year warranty on color fading up to five (∆5) Hunter units on a metal roof and you think the paint has faded beyond ∆5 units before the warranty has expired, contact the manufacturer. They’ll come to the site and inspect the panels to determine if there was a failure in the paint system or if some other event has occurred to alter the color. From there, the manufacturer can investigate further and determine the correct course of action.
The warranty should spell out the ∆E units and if any specific colors within the warranty have variations. For instance, brighter colors generally have less of a fade warranty and most metallic colors do not carry a color warranty at all because there is no way to measure them with a color spectrophotometer.
Most warranties will have differing ∆E units for metal roof panels and metal wall panels because the two are not subject to the same amount of sunlight (wall panels are typically covered at a lower ∆E number than roofing).
Chalking is the whitish residue that can become visible on a painted or coated metal surface over time. As a panel is exposed to sunlight and UV rays, the resin begins to break down and degrade. Once the resin starts to break down and continues to be exposed to the sun, oxygen, and other pollutants, it loses its adhesion to the surface and those degraded particles begin to turn white. These particles will eventually become visible to the naked eye on the metal’s surface.
Often, the difference can be subtle. However, if you swipe the panel with your finger, you can notice the chalky residue on your skin.
The degree of metal roof chalking is dependent on the paint system, especially the resin type and quality. Assuming the same environmental conditions apply, the rate of chalking based on resin type is usually in the following order:
Chalking is measured using one or more of the methods defined in the ASTM D-4214 standard. This standard also defines parameters for the numbering system, ranging from Number 1 to Number 10 with Number 1 being the worst and showing signs of extreme chalking (see photo above). Warranties often cover chalking in excess of a specific number using a specific method to determine that number.
For example, if a manufacturer says that their warranty covers chalking in an excess of Number 8 using Method A, also called the Cloth Tape Method, the testing process would follow these instructions:
It’s important to remember that manufacturers and paint suppliers test their paint systems in the harshest of conditions well before the products ever hit the market. Testing helps manufacturers gauge how well their products perform so they can offer you and other consumers the correct warranty based on where your structure is located. Some of the tests measure for:
For example, some of the common paint testing methods include:
Remember to ask your manufacturer about the testing methods their paint supplier uses before their metal panel systems hit the market and that they can substantiate these tests. It’ll give you a better understanding of how trustworthy the manufacturer and their products are if they are willing to have a conversation about the results of weather testing and if the products are in line with industry standards.
In the end, nothing will keep outdoor metal panels safe from chalking and fading forever. But that doesn’t mean there aren’t ways to stretch out the life of a metal roof or wall panel system. Being proactive instead of reactive truly will make a difference.
If you want to import GOOD QUALITY Steel Coils from Vietnam, please contact us at:
– Email: firstname.lastname@example.org
– Mobile/Whatsapp/Wechat/Line/Viber: +84 973 765 730
– Website: https://steelvn.vn/