Dogtag114

So my wife tells me her late father washed his car in the rain because it looked cleaner. Since he's not around to ask, I thought maybe it doesn't spot due to a lack of minerals found in tap water.

A few weeks ago, I washed my car in the rain, let it ran on it for another hour and pulled it in the garage. Then I dried off only the driver's side of the car to experiment.

Would you believe the rain just dried up and disappeared with no spots?

It wasn't the music playing, tranquil experience I usually get from washing my car, but I thought it was interesting and good to know if you want to wash your car on a Sunday and its raining all day...

Eskareon

It depends on the hardness of the rain in your area as well as the light you're using to look at your car. And some paints hide water spots much better than others. Next clear, sunny day, take a look at your paint from various, close angles - I'd wager you'll see the water spots left behind by the rain. But if it requires blazing sunlight and your face being 6 inches from the paint to see them, I'd also wager it passes the "clean enough" test for 99% of drivers, hah.

Little anecdote here - my previous car, a Mazdaspeed 6, was black mica, essentially a metallic black color. When I bought it used from the dealer, I assumed the rain spots all over it were recent and would come off with a little washing. They never did. The harder rain water here in Georgia must have sat on that black paint throughout the summer sun and etched right into the clear coat. I could feel some of them with my finger nails.

I picked up a Porter Cable orbital buffer and after trying several polishes, I was able to reduce most of the rain spots to nearly invisible - I had to be in intense sunlight and pretty close up to see them. But that took hours and hours of work, though it was pretty fun nonetheless. Since then, I try my best to wash the car after rainy periods, before days of intense sunlight. Just in case.

Edit: Actually, I picked up my C63 used, and it had a fair amount of light water spots as well. They were most noticeable on the carbon hood since it was darker. I was able to polish them out easily. I've heard detailers use a saying that goes something like, any surface parallel to the ground will have issues. Meaning, anywhere that water and debris can collect and then bake in the face of the sun. Roof, hood, trunk, bumper ledge,etc. These tend to show spotting issues before the other body panels do.

F355C5

I'll post later when I go to the garage and look at my car. It rained last night and it will be dry . Hope it looks good ,because if it is water spotted I will have to wash the car.

JumpinJim

Rain itself has a TDS level of 0 so it won't spot on its own. It can pick up some contaminants on the way down, but if it's been raining a while that won't be an issue. When it mixes with dust and dirt already on the car it creates spots. The problem is rainwater that's been on the ground that splashes up onto the car that's dirty.

coladin

I don't know why but this made me LOL! Therapy...

sinape62

Eskareon- where do you live in GA? I'm in Fayetteville.

Shellbmb

I once left my Jet Black M roadster in the parking spot next to my house and I didn't realize the sprinkler system covered that area. And my sprinklers are tied into the well water. Let's just say the next day after all that dried I was nearly in tears when I walked out. Water spots everywhere!! And huge ones. I honestly thought the paint was ruined after I quickly tried to re-wash it with no success. But my detailer worked miracles. And this was just before I was to turn it in back to the leasing company.

So the quality of water has a lot to do with hit. I assume our well water is very hard.

F355C5

Forgot to post my finding sorry. No water spots on car when dried in garage.