ASTM F1515: Measuring Light Stability of Resilient Flooring Materials
What Is ASTM F1515?
ASTM F1515 is the standard test method for measuring the light stability of resilient flooring by color change. It evaluates the resistance of vinyl, rubber, linoleum, cork, and other resilient flooring materials to color change caused by exposure to artificial UV light—a critical performance attribute for flooring installed in naturally or artificially lit environments.
Light stability testing per ASTM F1515 is essential for the resilient flooring, interior design, and commercial property sectors, where flooring appearance must remain consistent over years of exposure to sunlight and artificial illumination without fading, yellowing, or bleaching.
Why Light Stability Matters for Resilient Flooring
Resilient flooring installed near windows, in skylighted spaces, or under intense artificial lighting is continuously exposed to UV and visible light radiation. This exposure drives photochemical reactions in pigments, plasticizers, stabilizers, and polymer backings that cause:
- Fading: Loss of color saturation due to pigment photodegradation
- Yellowing: Oxidative discoloration of polymer matrix or plasticizer degradation products
- Bleaching: Localized loss of color in lighter pigment systems
- Surface chalking: Surface degradation creating powdery deposits
Light-induced color change is one of the most common appearance-related complaints in commercial flooring installations and a key criterion in product specification and warranty claims.
ASTM F1515 Test Procedure
Light Source
ASTM F1515 uses a xenon arc lamp weatherometer (as defined by ASTM G155) with daylight filters to simulate the UV and visible spectrum of sunlight. Xenon arc provides a closer spectral match to solar radiation than UV fluorescent lamps, making it more representative of actual installation conditions.
Test Conditions
- Irradiance: 0.35 W/m² at 340 nm (standard xenon weathering condition)
- Specimen conditioning: Half of each specimen is masked (covered) to serve as the unexposed reference; the other half is exposed to the light source
- Temperature: Black panel temperature controlled (typically 63°C for standard conditions)
- Exposure duration: Typically 72–96 hours of exposure (equivalent to a defined radiant energy dose)
Color Measurement
Before and after exposure, color is measured using a spectrophotometer or colorimeter in accordance with ASTM D2244. Color difference (ΔE) is calculated using the CIE Lab* color space:
ΔE = √(ΔL² + Δa² + Δb*²)
Where ΔL* = lightness change, Δa* = red-green shift, Δb* = yellow-blue shift.
Acceptance Criteria
Flooring specifications typically define a maximum allowable ΔE value after the defined exposure. Common specifications require ΔE ≤ 8 for acceptable light stability; premium products may require ΔE ≤ 4. Products with ΔE > 8 are considered to have poor light stability.
Flooring Materials and Light Stability Performance
| Material | Typical Light Stability | Key Concern |
| Luxury vinyl tile (LVT) | Good to excellent | UV stabilizer type and concentration |
| Homogeneous vinyl | Good | Plasticizer yellowing |
| Linoleum | Moderate | Natural oil oxidation (recovers in light) |
| Rubber flooring | Variable | Pigment type sensitivity |
| Cork | Fair | Natural tannin fading |
Why Choose Infinita Lab for ASTM F1515 Light Stability Testing?
Infinita Lab offers ASTM F1515 light stability testing and comprehensive weathering and color stability testing for flooring and interior materials through its nationwide accredited laboratory network. Our experts provide fast, accurate color measurement and technical interpretation of light exposure results.
Looking for a trusted partner to achieve your research goals? Schedule a meeting with us, send us a request, or call us at (888) 878-3090 to learn more about our services and how we can support you. Request a Quote
Frequently Asked Questions (FAQs)
What is the difference between ASTM F1515 and ASTM G155 for light exposure testing? ASTM G155 is the standard practice for operating xenon arc light apparatus for exposure and irradiance of non-metallic materials—it defines how to operate the xenon weatherometer (irradiance levels, filters, temperature control). ASTM F1515 is a product-specific application standard that specifies how to use the xenon arc apparatus for testing resilient flooring and how to evaluate the results (ΔE color change).
Why is the unexposed half of the specimen used as a reference in ASTM F1515? Masking half of each specimen creates a side-by-side comparison of exposed vs. unexposed material from the same production lot and batch—eliminating batch-to-batch color variation from the color change calculation. The ΔE calculated between the exposed and masked halves represents only the color change due to light exposure, not initial lot-to-lot variation.
How does linoleum's light stability behavior differ from vinyl? Linoleum contains linseed oil, which yellows when stored in darkness (due to oxidation without photobleaching) but recovers its original color when re-exposed to light—a phenomenon known as "linoleum bloom." ASTM F1515 testing of linoleum should account for this by adequately conditioning samples before masked/exposed comparison.
What UV stabilizers are used in resilient flooring to improve light stability? HALS (Hindered Amine Light Stabilizers) and UV absorbers (benzophenones, benzotriazoles) are incorporated into the wear layer of LVT and other vinyl flooring products to scavenge free radicals and absorb UV energy before they cause pigment and polymer photodegradation. The type, concentration, and distribution of UV stabilizers directly determine ASTM F1515 performance.
Is ASTM F1515 suitable for predicting actual years of service before noticeable fading? ASTM F1515 provides a comparative ranking of products and a pass/fail criterion against a specification—it is not designed to predict calendar years to visible fading in a specific installation. Correlation between xenon arc exposure (kJ/m² radiant energy) and years of indoor solar exposure depends on geographic location, window orientation, and glazing UV transmission—making absolute service life prediction complex and highly site-specific.
