Contemplating Water Spots

[Mikeman]

Given moderately hard tap water, and CLEAN, well-protected paint, which of the following situations is toughest on the paint if not promptly attended to? Rank them in order of severity if you wish.



A) Water dries in the shade, paint temp 70 F.

B) Water dries in the shade, paint temp 90 F.

C) Water dries in direct sun, paint temp 70 F.

D) Water dries in direct sun, paint temp 90 F.



If the car was put into the garage after the water dried under the above conditions, and left undisturbed for 7 days, what would you expect to find when you returned (besides dust)? How tough would it be to remove any water spots? Would a QD do it? Maybe a full wash? A full wash including vinegar treatment? Would you expect any etching?



Just out of curiosity, what's your guess as to the surface temperature of a car parked in the mid-day sun for several hours with an air temp of 90 F? I suppose color would make a difference here. I'd guess 120 F to 135 F.



I'm just trying to get a grip on water spots here. I want to get an idea of what I can get away with WITHOUT using my car as a test subject. THANKS !!



Mikeman

 

[oaevo8u]

I would say that D would have to be the worst, and if I was to rank them D,C,B,A.....im guesing though

 

[Mikeman]

If C is worse than B, then sunlight itself causes problems, not the heat generated by sunlight. I say this because the paint temp of item C is only 70 F, where B is 90 F. Situation B is in the shade, but much warmer. You could think of situation C as a sunny day in late fall.



I think surface temperature is what makes water more dangerous, not sun or shade. It's just that higher temps will USUALLY be found when sunlight is present. Higher temps = quicker evaporation = worse spotting. I may be totally wrong here. That's one reason I started the topic.



Mikeman