GMW 14162 Color Fastness to Artificial Weathering

The “GMW 14162 Color Fastness to Artificial Weathering” standard, developed by General Motors Worldwide (GMW), describes a test method used to evaluate the resistance of automotive interior materials to artificial weathering.

This standard uses a xenon arc light source to simulate the effects of sunlight, heat, and humidity that automotive materials might be exposed to inside a vehicle. In addition to color fastness, this method is also used to evaluate material degradation caused by prolonged exposure to simulated sunlight.

Vehicle interior materials are constantly exposed to solar radiation through the windshield and windows. Over time, this exposure can cause:

• Color fading
• yellowing
• Darkening or discoloration
• Loss of brightness
• Surface degradation
• Cracking or brittleness
• Changes in appearance
• Degradation of coatings and polymers

The GMW 14162 standard provides a controlled laboratory method to accelerate these effects.

Artificial abrasion is the accelerated exposure of a material to controlled environmental conditions designed to reproduce key aspects of natural wear. In the GMW 14162 standard, the primary radiation source is a xenon arc lamp. The test environment may also include high temperature, humidity, and alternating light/dark periods. The aim is not simply to expose a material to ultraviolet light. The test is designed to reproduce a combination of environmental stresses that might occur inside a vehicle. This is particularly important for interior components because temperatures on surfaces exposed to sunlight can be significantly higher than the ambient temperature inside the cabin.

The GMW 14162 standard defines four possible exposure methods. These methods differ primarily in terms of radiation wavelength, temperature, and whether the samples are exposed to alternating periods of light and darkness:

• Method A Light and Dark Exposure: This method uses alternating light and dark exposure with a specific black standard temperature of approximately 100 degrees and a control point of 420 nm. This method is based on ISO 105-B06 standard exposure condition No. 3. This approach is useful where the behavior of the material under both radiation and high temperature is important.
• Method B - Light exposure only: This method uses continuous light exposure at approximately 100 degrees, with radiation controlled in the 300-400 nm range. This approach is also based on ISO 105-B06 standard exposure condition No. 3. The absence of a dark period makes this method particularly useful in situations where continuous radiation exposure is required.
• Method C: High-temperature light exposure only: This method raises the specified temperature to approximately 115 degrees while keeping the radiation in the 300-400 nm range. This approach corresponds to ISO 105-B06 standard exposure condition No. 1. Due to its higher temperature, Method C represents a more severe thermal/radiation exposure than Method B and may be significant for materials expected to be exposed to high solar loads.
• Method D Light and Dark Exposure: This method uses alternating light and dark exposure at approximately 89 degrees, with radiation controlled at 340 nm. This method is based on ISO 105-B06 exposure condition No. 5 and is related to the SAE J1885/SAE J2412 family of standards, with SAE J2413 being a complementary standard. Method D is particularly important for automotive interior weather resistance programs and is still listed among the accredited General Motors laboratory capabilities.

A xenon arc weatherproof chamber produces radiation intended to reproduce the spectral characteristics of natural sunlight. The equipment monitors the following parameters:

• Radiation intensity
• Spectral distribution
• Exposure temperature
• Relative humidity or moisture conditions in the specified locations.
• Light/dark sequence
• Exposure time

Commercial xenon arc weather resistance systems specifically list the GMW 14162 standard among the automotive test methods they can perform. Therefore, laboratory equipment needs to be configured appropriately for the specific method requested.

The GMW 14162 standard is specifically applicable to automotive interior materials. Accredited automotive laboratories list the standard for the following materials:

• Coated textiles
• Plastic roll products
• Skin
• Leather fiber sheets
• Plastics
• elastomers
• Films/foils
• Textiles
• yarns

Typical automotive applications include:

• Instrument panel trims
• Door trim materials
• Upholstery materials
• Ceiling fabrics
• Armrest covers
• Decorative films
• Interior plastics
• Coated fabrics
• Synthetic leather
• Polymer components

The exact material, exposure method, duration, and acceptance criteria generally depend on the relevant material specification or component requirement.

One of the primary aims of the GMW 14162 standard is to determine whether a material retains its color and appearance after accelerated exposure. Typical assessments include:

• Color change: The exposed sample is compared to an unexposed reference. Instrumental color measurement can be used to gauge the changes.
• Visual appearance: The sample is examined in terms of the following:
  • Fading
  • yellowing
  • Staining
  • Discoloration
  • Surface changes
  • Material degradation
• The test can also reveal physical impairments such as those listed below:
  • Cracking
  • Fragility
  • Surface degradation
  • Loss of coating integrity
  • Other visible signs of aging

In conclusion, the GMW 14162 standard is more than just a simple color fading test. It can also serve as an assessment of artificial weathering/deterioration.

The GMW 14162 standard is important because automotive interior materials must maintain their appearance and functional integrity throughout the vehicle's lifespan. A material that looks perfect when new can significantly deteriorate after prolonged exposure to sunlight. For example, a dashboard material might initially have an acceptable dark color. However, after prolonged exposure to sunlight, it may become lighter, take on a brownish or yellowish appearance, or undergo surface degradation.

Tests conducted according to the GMW 14162 standard allow manufacturers to identify these problems before production vehicles are released to the market. The main benefits of these tests are as follows:

• Material selection: Helps engineers compare alternative materials and coatings.
• Supplier qualification: Material suppliers can demonstrate compliance with General Motors requirements.
• Durability estimation: Accelerated weather resistance provides information about resistance to environmental aging.
• Appearance control: Helps prevent unacceptable fading and discoloration.
• Product development: Weak formulations can be identified and improved during development.
• Quality assurance: Production materials may be periodically tested to verify their consistent performance.

For many years, our organization, with its competent and experienced staff, has been understanding the needs of its clients, providing the advanced testing services they require, and assisting them in the establishment, implementation, and improvement of management systems. Within this framework, we also provide testing services in accordance with the GMW 14162 standard.