Repelling Repellant: Protecting Buick Interiors from Sunscreen, Bug Spray and Sweaty Mitts
DETROIT - June 18, 2014: Whether you are heading to the beach or the backwoods this summer, protecting your skin with sunscreen or bug spray is essential.
Similar to your skin, materials used in Buick interiors also need a protective coating to help keep them looking new. That includes protection from sun exposure and perspiration – and from the sunscreen and bug repellant that can be transferred to vehicle surfaces from human skin.
The General Motors Materials Test and Engineering group conducts a battery of durability experiments to help ensure a vehicle’s carpet, leather and fabric seat upholstery, wood and metal trim, plastics and other materials are less subject to 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,” said Doug Pickett, engineering group manager for the Materials Test and Engineering group. “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 test how well protective coatings on the dash, steering wheel or upholstery offer resistance to sunscreen and DEET, the substances are applied to the materials and baked in an oven. After baking, engineers evaluate the effects on the materials.
To test for material durability in heat and ultraviolet light, lab engineers at the GM Vehicle Engineering Center in Warren, Mich., use artificial light similar to a tanning booth for two to six weeks before analyzing results.
“The simulated UV light allows us to do the testing much faster and it allows us to do more experiments to improve the materials,” Pickett said. “But to absolutely confirm the durability, we have found we still need to use the natural sunlight test.”
Following initial tests in the lab, materials are exposed to natural sunlight in Arizona by placing them in special glass boxes that rotate with the sun for up to seven months at a time.
Sweat tests using a synthetic perspiration solution also are an important component of material durability. These tests are conducted on areas that have high skin contact, such as steering wheels and control knobs.
GM engineers apply perspiration solutions to material samples for two and a half hours before letting them dry. Once dried, the sample is scraped to determine if the material was softened or damaged. After the scrape test, the material is exposed to artificial light to assure it can withstand the combination of sun and sweat.
After examining the results, the Materials Test and Engineering works with material suppliers to fine-tune protective coatings on a particular material.
“While it is easy to make leather resistant to chemicals or abrasion, it is very difficult to find the balance of durability while maintaining the desirable look and feel that a Buick customer expects,” said Pickett. “The texture is an important factor, so it can’t be too hard, too slick or too sticky.”
The GM Materials Test and Engineering group consists of 13 engineers, all of whom perform a wide range of experiments on interior materials including leather cold-crack testing, seam fraying, tear strength, corrosion, dent and scratch resistance on hard surfaces and hook and loop fastener resistance on fabrics.