It's Murphy's Law: just after you wash your car, it's guaranteed to rain. Keeping your vehicle looking spick and span is a tough job sometimes.
“But what’s the big deal?” You might be tempted to say. “It’s all water anyway, right?” Wrong!
While it might seem a good idea – after all, it’s cheaper than a car wash and less hassle than doing it yourself – the rain often leaves your car looking worse than when it started. That’s because, weirdly enough, rain tends to make cars dirty.
So, what’s up with that? Are clouds, like, unclean? Do they just need a good hoover and dust down? Where’s all the dirt coming from?
Apparently, the scientific reason that rain makes your car dirtier is that the air nearer the ground is filled with particles like pollen, dust, pollutants, contaminants and smoke. As the rain falls towards the ground, its force swishes these particles into the raindrops, so that by the time they hit the earth they’re saturated with them.
This process creates what’s called acid rain. And, no, that doesn't mean there's acid falling from the sky! When metal oxides dust and chemicals combine with hard water, it will commonly create spots on the surface of your car.
Acid rain can cause more damage than it helps – it can etch into your car’s duco and make it look dull and lacklustre. That’s why, after a rain shower, you’ll see a mosaic of grime left on your car.
If you’ve ever taken a deep, cleansing breath outside after a deluge, you’ve probably noticed that the air is cleaner and clearer just after a rainstorm. That's because all those particles have been swept away. But if the same rain falls on your nice newly washed car and dries, those particles are left behind.
Sure, if your car is plastered in dirt and mud, a nice shower might loosen it up a bit. But mostly it will just make it filthier. And if you the contaminants left over after the rain dries, your car’s paint finish will suffer.
Snow, hail and sleet are just as bad. If you live in an area where roads are salted to reduce ice, these chemicals can mix with the water and eat into your duco and wheel wells, creating a breeding ground for rust.
Besides, natural rain showers won’t wash all your car, top to bottom. Generally, only the exposed areas are wetted, allowing dirt to congregate in hard to reach nooks and crannies and leaving your car crying out for a good scrub with soap and clean water.
A rainstorm is never a viable replacement for the kind of good, deep clean you’ll get at a car wash or professional car cleaning company – one that uses pure water (not recycled water). Even better, you should get an expert hand wash around every two weeks or so to keep the paint looking bright.
In fact, it’s a good idea to head straight to your local car wash after rains and ask the professionals to remove water spots, minerals and calcium staining caused by acid rain. You might also want to ask for a protective finish to be applied to protect your car’s exterior surface against common pollutants.