Hey everyone, it’s Mia from the cladding team—let’s cut right to the chase because if you’re dealing with exterior building materials, one thing that makes or breaks your project is color holding up, right? Last month we had an architect hit me up panicking because their old composite cladding was faded so bad after 2 years, they had to rip half of it off their mixed-use building. That’s the kind of headache we built our CO-extrusion cladding to avoid, so today I wanna break down the color fastness of our product—no jargon, just real talk about what it means for your jobs, how we test it, and why it’s not the same as that cheaper stuff you might be looking at. CO-Extrusion Cladding
First off, let’s get one thing straight: color fastness isn’t just “does the color stay pretty?” It’s how it holds up against the four big environmental bullies: UV rays, rain, temperature swings, and pollution. For CO-extrusion cladding specifically, the way we make it is a huge difference-maker. If you’re new to the process, CO-extrusion means we melt two separate polymer layers (usually PVC, but we also do co-ex with HDPE for some projects) and fuse them together while they’re still molten—no glues, no adhesives, just molecular bonding. That outer layer isn’t a thin paint or a thin wrap we slap on after; it’s a full, fused layer all the way through the outer part of the cladding. No peeling, no chipping, and way less chance of the color wearing off from the surface.
Now, let’s talk about UV fastness, because that’s the big one for anyone in places with intense sun—like the Southwestern US, Mediterranean, Southeast Asia, anywhere that’s not super cloudy 24/7. Most lower-quality cladding uses a “coated over” system, where they spray or roll on a color coating after the base cladding is extruded. That coating might be a basic pigment mixed with some UV stabilizers, but it’s sitting on top of the plastic, so over time, UV radiation breaks down that coating’s molecular structure, making it fade, chalk (that powdery residue you get when the surface breaks down), or peel right off. Our CO-extrusion process? We mix UV stabilizers and fade-resistant pigments directly into that outer extruded layer before we fuse it to the base. We use pigments that are specifically formulated for exterior polymers—no cheap indoor pigments here. I can throw up a quick example: our standard gray cladding is a carbon-black-based pigment mixed with 3% of our custom UV stabilizer blend, and our test data shows it holds up 2x longer than a coated PVC cladding we tested against last year. Wait, but don’t take my word for it—we do actual accelerated weathering tests, not just lab nonsense.
Accelerated weathering testing is basically the industry way to simulate years of sun and rain in a few weeks. We use a QUV chamber, which blasts UV light at a specific intensity and cycles in condensation to mimic rain and dew. For our CO-extrusion cladding, we run those tests for 3,000, 5,000, even 8,000 hours. The ISO standard for exterior building cladding is usually around 1,000 hours of QUV exposure with a delta E (that’s the color difference number—lower is better) of less than 2. What’s delta E? It’s a numerical score that measures how much two colors differ; anything under 2 is basically undetectable to the human eye, and we hit that delta E mark at 5,000 hours, and most of our custom color runs barely top delta E 1 at 5,000 hours. Last quarter we had a commercial project in Phoenix, AZ that’s been using our medium-brown CO-extrusion cladding for 3 years now—they sent us a photo last week, and a quick color check against the sample we sent them showed delta E 0.8. That’s insane, right? For comparison, the coated cladding they used on a different building by the same team had a delta E of 4.2 after the same 3 years.
But color fastness isn’t just UV—there’s also water fastness, which is how the color holds up to rain, humidity, standing water, even things like snowmelt that might have road salt or other chemicals in it. With CO-extrusion, since the outer layer is fused to the base, there’s no gap or weak point between the two layers where water can get in and wash out pigments. Coated cladding has a seam between the coating and the base, so over time, water seeps in, breaks down the coating, and causes blistering or discoloration. We tested our CO-extrusion cladding in a 1,000-hour water immersion test, submerging samples in both regular tap water and slightly alkaline water (to mimic hard water in places like Texas) and we saw zero color shift, no blistering, no pigment leaching. We also had a project in Florida, where salt air is brutal on building materials—our coastal CO-extrusion cladding samples, which have an extra anti-corrosion additive in the outer layer, have held up perfectly for 2 years, no salt-related discoloration. That’s a big deal because salt air eats away at any weak coating layer way faster than regular rain.
Another thing people sleep on is heat and cold fastness. If you’re in a place that goes from 100°F+ in summer to 10°F or lower in winter, that temperature swing can cause materials to expand and contract, which is a problem if your color layer is just sitting on top. Coated cladding will often crack or peel when the plastic expands and contracts unevenly, exposing the faded base layer. Our CO-extrusion layers are fused together, so they expand and contract as one single material—no separation, no cracking, no peeling of the color layer. We tested that by putting samples through 100 thermal cycles, going from -40°F to 140°F each cycle, which is way more extreme than almost any project will see, and the delta E after that was still under 1.5. The coated sample we tested? It had a delta E of 5.8, plus tiny cracks in the coating that you could see under a magnifying glass. That’s the kind of thing you don’t notice for a year, but by year 3, it’s a big enough deal that you have to replace panels.
Now, let’s be real—there are some caveats here, because no product is perfect, and I don’t wanna oversell this. First, color selection matters. We can’t make neon colors, or super vibrant hues, that are never gonna be fade-resistant, because pigments that are that bright don’t hold up well to UV. We have a range of standard colors that are tested and proven, and we can do custom colors if you’re okay with a slightly longer lead time—we just don’t guarantee neon or super-saturated colors for projects where color fastness is the top priority. Second, installation matters. If you install the cladding wrong, like not leaving the proper expansion gaps, or letting water pool behind the panels, even the best color fastness won’t save it. We always send an installation guide with every order, and our team is always here to help walk your installer through it if they have questions. Third, maintenance is basic—just wash the panels once a year with mild soap and water, don’t use pressure washers on the highest setting because that can scratch the surface (scratches might look like discoloration, but they’re just surface marks, not actual fading).
I know a lot of suppliers will tell you their cladding is “100% fade-proof” and throw out vague numbers like “10 year warranty” without backing it up. We do a 15-year limited warranty on all our CO-extrusion cladding related to color fastness—meaning if the delta E goes over 2 in that time, we’ll replace the panels for free. That’s not something we can do with coated cladding, because most coated cladding only has a 3-5 year warranty for color, if that. Last year we had a residential project in Colorado that had a custom gray color with a slight blue tint, and after 4 years, the home owner noticed a tiny amount of fade (delta E 2.1, which is just barely over our threshold). We sent a full set of replacement panels at no cost, no questions asked. That’s the kind of accountability you don’t get from the cheaper suppliers.
Wait, also, a lot of people confuse color fastness with color uniformity—like, do all the panels come out the same color? That’s part of CO-extrusion too. Since we mix the color pigments directly into the outer layer during extrusion, every panel is the same from end to end, no variation in the surface that you get with coated cladding, which can have slight color shifts between batches. We measure every batch with a spectrophotometer to make sure the delta E between any two panels is under 0.5, so when you put up a whole facade, it looks consistent, not patchy. That’s huge for architects and contractors who need a seamless look for a project.
Let me wrap this up with something practical, because I know you’re here for your projects, not just lab talk. If you’re working on a commercial building, a residential development in a sunny climate, or anything that needs to look good long-term without huge maintenance, our CO-extrusion cladding’s color fastness is one of our biggest selling points. We’ve done projects for office parks, apartment complexes, retail stores, even universities, and every single one has come back with positive feedback about how the color hasn’t faded at all, even after 5+ years. If you’re tired of dealing with faded cladding that needs replacement every few years, or you’re tired of arguing with suppliers who don’t back up their claims, reach out to our team to talk through your project, get sample panels, and we can give you a custom quote that fits your budget and timeline.
Don’t settle for coated cladding that’s gonna look worn out in 3 years. CO-extrusion is the future of exterior cladding, and the color fastness is why.
WPC Cladding References
- American Society for Testing and Materials (ASTM) D4587, Standard Practice for Fluorescent UV-Condensation Exposures of Building Materials
- International Organization for Standardization (ISO) 105-B02, Textiles – Tests for colour fastness – Part B02: Colour fastness to artificial light: Xenon arc fading lamp test
- Plastics Europe. (2021). Extruded Polymer Cladding for Outdoor Applications: Performance Properties and Durability Standards. Brussels, Belgium: Plastics Europe Association.
- Q-Lab Corporation. (2022). Accelerated Weathering of Building Materials: Practical Guide to Testing and Performance. Cleveland, OH: Q-Lab Corporation.
Zhejiang Timber Biology New Material Co., Ltd.
As one of the most professional co-extrusion cladding manufacturers and suppliers in China, we’re featured by quality products and good service. Please rest assured to wholesale custom made co-extrusion cladding at competitive price from our factory.
Address: No. 192, Longshan Road, Zhongguan Town, Deqing County, Huzhou City, Zhejiang Province
E-mail: info@tongrui.cc
WebSite: https://www.utimberwpc.com/
