Aussies know the meaning of the words slip, slop slap, but you’re probably not aware that sunscreen pose a threat to your car.

The chemicals contained in sunscreen, hand sanitiser and insect repellent that you rub on your skin can prematurely age surfaces touched inside a car.

In fact, the higher the sun protection factor (SPF) offered by sunscreen, SPF 50+ for instance — the more of these chemicals it is likely to contain.

Higher sun protection factor lotions contain greater quantities of titanium oxide that can react with plastics and natural oils found in leather, especially when it is hot.

Diethyltoluamide, or DEET, is the most common active ingredient in insect repellents.

Figures show the European market for hand sanitiser, including gel, foam and wipes, many of which contain ethanol, is expected to rise by 60 per cent from 2018 to 2024 — from $371 million to $593 million.

It’s an ongoing challenge for engineers to deal with, as they continually test new products on materials that are used in the manufacture of motor vehicles, to  development resistant coatings that ensure they look good for years to come.

“From hand sanitisers to sun lotions to insect repellent, consumer trends are constantly changing, and new products are coming on to the market all the time,” Ford of Europe senior materials engineer Mark Montgomery said.

“Even the most innocuous seeming product can cause problems when they come into contact with surfaces hundreds and even thousands of times a year.”

Teams in Dunton and Cologne, Germany, test at temperatures of up to 74 degrees, the temperature the inside of a car parked at the beach on a hot day might reach (it might get a little hotter than that in Australia).

In other tests they simulate extended exposure to the sun, with samples bombarded with ultra‑violet light, equivalent to the brightest place on earth, for up to 1152 hours (48 days).

They also test plastics for strength at temperatures as low as minus 30 degrees when they become most brittle, repeatedly bouncing a rubber ball – that is 10 times heavier than a regulation football – to ensure the plastic doesn’t crack.

Based on the findings, the chemical constitution of protective coatings can then be reformulated so that interiors are protected.

Testing also applies to storage accessories, sold through Ford Customer Service Division, such as boot liners and interior plastic covers.

“Sometimes what we do requires a bit of detective work.

“There were instances of particularly high wear in Turkey and we managed to trace it back to ethanol potentially being a contributing factor, and most likely a popular hand sanitiser that contained 80 per cent ethanol – far higher than anything we’d seen before.

“Once we knew what it was, we were able to do something about it.”

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Riley

Chris Riley has been a journalist for almost 40 years. He has spent half of his career as a writer, editor and production editor in newspapers, the rest of the time driving and writing about cars both in print and online. His love affair with cars began as a teenager with the purchase of an old VW Beetle, followed by another Beetle and a string of other cars on which he has wasted too much time and money. A self-confessed geek, he’s not afraid to ask the hard questions - at the risk of sounding silly.