Sunlight vs. Surfaces: How Kleenstone™ Stands the Test of Time
Sunlight vs. Surfaces: How Kleenstone™ Stands the Test of Time
Understanding UV Exposure and Its Impact on Surfaces
When selecting materials for kitchens, bathrooms, or outdoor spaces, long-term durability under sunlight exposure is a key consideration. Ultraviolet (UV) radiation, particularly UVA (340nm) and UVB, can cause surfaces to fade or discolor over time. To assess its durability, Kleenstone™ underwent a rigorous accelerated UV testing process, simulating 10–15 years of real-world indoor kitchen sunlight exposure. The results showed minimal color change, even under extended test conditions.
Laboratory UV Testing: Methodology
Kleenstone™ samples were subjected to 1,000 hours of continuous UV exposure at 340nm, a wavelength known for its impact on color stability. This test approximates:
- 1 to 1.5 years of direct outdoor UV exposure, assuming 8 hours of peak sunlight per day.
- 10 to 15 years of typical indoor kitchen UV exposure, factoring in real-world variables that significantly reduce UV impact indoors.
Why 1,000 Hours Simulates 10–15 Years Indoors
Indoor UV exposure is considerably lower than direct outdoor exposure due to several key factors:
- Limited direct sunlight exposure: Indoor surfaces typically receive only 0.5–2 hours of direct sunlight per sunny day, rather than continuous outdoor exposure.
- UV filtering by windows:
- Single-pane glass blocks 25% of UV radiation, allowing 75% to pass through.
- Double-glazed glass blocks 42% of UV, allowing 58% to reach indoor surfaces.
- Seasonal and weather variability: Cloudy conditions, window blinds, and shading from nearby buildings further reduce UV intensity.
- Reflection and indirect UV exposure: Unlike outdoor surfaces, which receive direct high-intensity UV radiation, indoor surfaces are more often exposed to indirect or scattered UV light, further reducing total UV exposure.
Given these conditions, 1,000 hours of controlled UV exposure provides a reliable estimate for 10–15 years of real-world indoor UV exposure in a kitchen setting.
UV Test Results: Measuring Colour Stability
Color changes were evaluated using a 0 to 4 scale, where:
- 0–1: No visible change (Excellent UV resistance)
- 1–2: Barely noticeable shift (Strong durability)
- 2–3: Slight color change, visible upon close inspection
- 3–4: Minimal but subtle change, noticeable when compared directly
Even the highest recorded change on this article was a minor shift, demonstrating that Kleenstone™ surfaces exhibit exceptional long-term color stability.
Kleenstone™ UV Resistance: Test Results
Kleenstone™ Colour | Color Change Score | Expected Impact Over Time |
Salt | 0.40 | No visible change; ultra-stable color |
Pearl | 0.81 | No visible change; ultra-stable color |
Mist | 1.05 | Remains visually consistent |
Sunset | 2.52 | Slight change, visible only with A/B comparison |
Rocky | 0.58 | No visible change; ultra-stable color |
Star | 0.61 | No visible change; ultra-stable color |
Tide | 1.22 | Remains visually consistent |
Vortex | 1.15 | Remains visually consistent |
Spring | 1.61 | Slight change, visible only with A/B comparison |
Cava | 3.65 | Minimal but subtle shift after 10-15 years |
Even the most affected color (Cava at 3.65) displayed only a minor shift, which would not be easily noticeable in daily use.
Key Takeaways: Long-Term UV Resistance
- Kleenstone™ surfaces demonstrate durability against 10–15 years of indoor sunlight exposure, with minimal fading.
- Most colors, particularly lighter shades such as Salt, Rocky, and Star, exhibit virtually no color change over time.
- Indoor conditions, especially with double-glazed windows, significantly reduce UV impact compared to outdoor settings.
- Even in extended real-world scenarios, Kleenstone™ maintains its aesthetic integrity with minimal maintenance requirements.
For homeowners and designers seeking durable, UV-resistant materials, Kleenstone™ provides a proven long-term colution.
For Those Curious: How 1,000 Hours Translates to 10–15 Years
The accelerated UV exposure test simulates real-world conditions, but indoor UV exposure is significantly lower than outdoor environments. Below is an outline of the calculations used to estimate 10–15 years of real-world exposure from 1,000 hours of controlled UV testing.
Step 1: Outdoor vs. Indoor UV Exposure
Outdoor surfaces receives 8+ hours of direct sunlight per sunny day, while indoor surfaces, such as kitchen counters, generally experiences:
2 to 5 hours of direct sunlight per sunny day, depending on window placement and shading.
Less intense indirect UV exposure the remainder of the day.
Step 2: Adjusting for Seasonal & Weather Variability
While New Zealand receives 83 sunny days per year, real-world UV exposure is further reduced by cloud cover, shading, and indoor placement.
A more realistic estimate suggests that an indoor kitchen counter receives significant UV exposure only on 50–70 days per year.
Step 3: Factoring in Window UV Filtration
- Single-pane glass allows 75% of UV to pass through.
- Double-glazed glass allows only 58% of UV to reach indoor surfaces.
- Additional shading from eaves, curtains, and reflections further reduces exposure.
Thus, indoor UV intensity is only about 30–40% of outdoor UV exposure on average.
Step 4: Calculating Indoor UV Hours Per Year
Using these assumptions, an indoor surface accumulates:
- Lower estimate: 50 sunny days × 0.5 hours × 35% transmission = 9 effective UV hours per year.
- Higher estimate: 70 sunny days × 2 hours × 35% transmission = 49 effective UV hours per year.
At this rate, 1,000 hours of concentrated Lab based UV exposure would ≈ 20 years at consistent upper end and ≈ 100 years consistent lower end to accumulate naturally indoors.
To remain conservative and realistic, the claim is refined to:
1,000 hours of controlled UV exposure equates to 10–15 years of real-world indoor kitchen sunlight exposure.
Sources & References
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- Studies conducted using Laboratory Testing services provided by BRANZ
- New Zealand Climate Data – NIWA (National Institute of Water and Atmospheric Research)
- Glass UV Transmission Studies – Glass & Glazing Federation (GGF) reports on UV transmission through different glass types
- UV Exposure & Material Degradation Studies – ASTM G154 & ISO 4892-2 UV testing standards
- World Health Organization (WHO) Research – Data on UV intensity and transmission indoors
