Remember when Scotchgard was the latest and greatest thing to keep your interior clean from the rigors of kids and messes? General Motors has continued to research materials to keep your interior looking new.
Sun exposure, perspiration, sunscreen, and bug repellant all can alter the condition of an interior, which is why the General Motors Materials Test and Engineering group conducts a set of durability experiments to help maintain the integrity of a vehicle’s interior. Whether it’s carpet, leather and fabric seat upholstery, wood and metal trim, plastics, or other materials, GM has an interest in keeping it all from fading, discoloration, or premature wear from these and other substances.
Some of the experiments take months to complete. “Our group tests for durability and resistance to natural and artificial elements on materials you see and don’t see inside your Buick,” says engineering group manager for the Materials Test and Engineering group, Doug Pickett. “We test not only for sun exposure or humidity, but commonly spilled things like ketchup and mustard and even stronger substances like sweat, sunscreen and DEET, a chemical often found in bug repellent.”
To determine how well protective coatings offer resistance to sunscreen and DEET, substances are applied to interior materials and baked in an oven. After baking, engineers evaluate the effects. To test durability in heat and ultraviolet light, lab engineers at the GM Vehicle Engineering Center in Warren, Michigan use artificial light (similar to a tanning booth) for two to six weeks before analyzing results. Following initial tests in the lab, materials are exposed to natural sunlight in Arizona for up to seven months at a time.
“The simulated UV light allows us to do the testing much faster and it allows us to do more experiments to improve the materials. But to absolutely confirm the durability, we have found we still need to use the natural sunlight test,” adds Pickett.
Sweat tests, using a synthetic perspiration solution, are also an important part of material durability testing. These tests are conducted on areas that have high skin contact, usually the steering wheels and control knobs. Engineers apply “perspiration solutions” to material samples for 150 minutes before letting them dry, then the sample is scraped to see if the material softened or was damaged. After the scrape test, the material is then exposed to artificial light to determine whether it can withstand the combination of sun and sweat.
After examining the results, the Materials Test and Engineering group works with material suppliers to fine-tune protective coatings on a particular material.