ASTM D1499: Filtered Open Flame Carbon Arc Weathering Exposure for Plastics

What Is ASTM D1499?

ASTM D1499 is the standard practice for operating light- and water-exposure apparatus — specifically, the carbon-arc type — for the exposure of plastics. It defines the operating conditions, equipment setup, and exposure procedures for using filter, open-flame, and open-flame carbon arc lamps to subject plastic specimens to accelerated weathering simulating the UV radiation, heat, and moisture effects of outdoor solar exposure under controlled, reproducible laboratory conditions.

Carbon arc weathering is one of the oldest accelerated weathering technologies — predating xenon arc and fluorescent UV systems. While xenon arc instruments (ASTM G155) are now more commonly specified for new test programs due to their better simulation of full-spectrum sunlight, carbon arc testing remains specified in a significant number of existing product standards, OEM requirements, and regulatory frameworks — particularly in Japanese and some Asian market specifications.

Principle of Carbon Arc Weathering

Open flame carbon arc lamps produce intense UV radiation by creating an electric arc between two carbon electrodes. Different filter glass configurations modify the spectral output to better simulate the UV component of solar radiation reaching the Earth’s surface.

Two primary carbon arc types are used in ASTM D1499:

Sunshine Arc (Unfiltered or Daylight Filter)

The sunshine arc with a Corex D glass filter produces a spectral distribution that emphasizes the short-wave UV region — primarily simulating the UV component of solar radiation. Historically used for weathering tests where UV degradation is the primary mechanism of interest.

Enclosed Arc (Filtered with Borosilicate Glass)

Carbon arc enclosed in a borosilicate glass globe filter — producing somewhat different UV output compared to the open sunshine arc. Used in older test standards, particularly those derived from Japanese automotive specifications (JIS standards).

Test Equipment and Chamber Configuration

ASTM D1499 covers the Fade-Ometer® type apparatus (marketed by Atlas Material Testing) and equivalent carbon arc exposure chambers. Key chamber parameters include:

Irradiance (light intensity): Measured by a calibrated bolometer or actinometer — ensuring consistent UV dose delivery across different test runs.

Black panel temperature (BPT): Measured by a calibrated black panel thermometer — typically 63°C ± 3°C for standard plastic exposures, representing the surface temperature of a black specimen in sunlight.

Chamber temperature: Maintained at approximately 42–47°C for typical plastic exposures.

Water spray: Demineralized or deionized water spray is applied to specimens during defined wet cycle periods — simulating the effect of rain, dew, and condensation. Continuous light with a water spray, or alternating light/dark with a spray, provides the cyclic moisture exposure that is important for weathering acceleration.

Specimen mounting: Specimens are mounted on rotating racks that revolve around the carbon arc lamp — ensuring uniform exposure across all specimens throughout the test duration.

Exposure Cycles for Plastics

ASTM D1499 allows several exposure cycle options:

Continuous light (no spray): Used for initial screening and for materials where spray condensation effects are not a primary concern.

102 minutes light / 18 minutes light + spray: The most commonly specified cycle for plastics — providing 18 minutes of wet exposure per 2-hour cycle to simulate outdoor moisture cycling. Referenced in many plastic material standards as the standard aging cycle.

Other cycles: Various light/spray/dark combinations may be specified in the referenced product standard, depending on the simulated application environment 

Properties Evaluated After Carbon Arc Exposure

ASTM D1499 defines the exposure procedure but does not specify which properties to evaluate or the acceptance criteria. The referenced product standard defines these typical evaluations after carbon arc exposure, including:

Color change (ΔE, yellowness index change): Measured by spectrophotometry — quantifying UV-induced chromophore formation and color shift. ASTM D2244 for CIE Lab* color difference; ASTM E313 for yellowness index.

Gloss retention (ASTM D523): Specular gloss at 60° before and after exposure — measuring surface UV degradation effects on surface optical quality.

Tensile property retention (ASTM D638): Tensile strength and elongation after vs. before exposure — quantifying UV-induced chain scission and embrittlement.

Impact resistance retention (ASTM D256): Notched Izod or Charpy impact after UV exposure — particularly important for outdoor structural plastic applications.

Chalking (ASTM D659): Visual rating of surface chalk formation — indicating significant UV degradation of the polymer surface layer.

ASTM D1499 vs. ASTM G155 (Xenon Arc) for Plastics

While carbon arc (ASTM D1499) and xenon arc (ASTM G155) both provide accelerated UV weathering for plastics, key differences include:

Spectral distribution: Xenon arc with optical filters (particularly inner/outer borosilicate/soda-lime glass combinations) more accurately simulates the full-spectrum solar irradiance, including visible and near-IR components. Carbon arc produces a UV-heavy spectrum that over-represents short-wavelength UV relative to real sunlight.

Repeatability: Xenon arc instruments offer better lamp-to-lamp and run-to-run irradiance consistency due to irradiance monitoring and control systems.

Acceptance: For most new standard development, xenon arc (ASTM G155, SAE J2527) is preferred. Carbon arc remains specified in JIS (Japanese Industrial Standards) automotive and textile testing, and in many legacy product specifications where historical data continuity is required.

Industry Applications

Automotive: Carbon arc testing per JIS D 0205 for Japanese OEM exterior plastic components — specifying color and gloss retention requirements after defined exposure durations.

Textiles and Apparel: Carbon arc (Fade-Ometer) testing has long been used for textile colorfastness evaluation — AATCC TM16 references carbon arc for lightfastness testing.

Plastics and Coatings: Legacy specification compliance testing for export markets and historical data comparison with long-established product databases

Conclusion

ASTM D1499 carbon arc weathering testing — utilizing controlled UV radiation, temperature, and moisture exposure cycles — provides accelerated evaluation of plastic material durability under simulated outdoor conditions. These methods enable assessment of color stability, gloss retention, mechanical property degradation, and surface deterioration caused by UV exposure and environmental factors. Selecting the appropriate exposure cycle and test conditions based on material type, application environment, and specification requirements is essential for obtaining meaningful and comparable results, making the testing strategy as important as the performance outcomes themselves.

Why Choose Infinita Lab for ASTM D1499 Carbon Arc Testing?

Infinita Lab offers comprehensive accelerated weathering and UV testing services — including ASTM D1499 carbon arc, ASTM G154 fluorescent UV, ASTM G155 xenon arc, and full post-exposure property characterization — across its network of 2,000+ accredited labs in the USA. Our advanced equipment and expert professionals deliver highly accurate and prompt results for weathering qualification programs worldwide.

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