Sunscreen – bad for your car’s health?

Bought in ever increasing quantities, hand sanitisers and higher sun protection factor lotion may be good for our health but they can be bad news for our cars.

Chemicals found in some such products can react with surfaces, causing them to wear prematurely unless they are protected by special finishes.

This is a challenge that our engineers deal with daily, continually testing new products on the materials that are used in its vehicles and supporting the development of resistant coatings that can ensure they look good for years to come.

Mark Montgomery, senior materials engineer at our Materials Technology Centre, in Dunton Essex.

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

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 $371.92 million in 2018, to $593.62 million by 2024. Higher sun protection factor lotions contain greater quantities of titanium oxide that can react with plastics and natural oils that are found in leather, especially when it is hot. Diethyltoluamide, or DEET, is the most common active ingredient in insect repellents.

Our teams in Dunton and Cologne, Germany, test at temperatures that can in some cases reach 74°C – the temperature the inside of a car parked at the beach on a hot day might reach. 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 1,152 hours (48 days).

They also test plastics for strength at temperatures as low as -30°C when they become most brittle, repeatedly bouncing a rubber ball – that is ten 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. This helps us to keep interiors looking good for the lifetime of the vehicle, which can help owners when it’s time to sell their car. Testing also applies to storage accessories, such as boot liners and interior plastic covers.

Richard Kyle, materials engineer, also based in Dunton.

“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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