Why shouldnt we wash our car when the paint is hot??

[qaz393]

Why shouldnt we??? any downside?? i see so many people take their cars to a automated carwash on a hot sunny day and im pretty sure 80% of the people there have hot paint already.

 

[rott3np3anut]

Well it makes it harder. The soap can dry and leave marks which are annoying to get out. The water will dry faster and leave water marks. Also pouring cold water on hot metal causes it to contract, which isn't too good for it.

 

[LegacyGT]

It drys very quickly, and you end up with water spotting.

 

[maluminas]

I wash my car when it's hot, but i park it in the shade and slowly mist it with the hose to cool it down first. The whole point is to prevent the soap and/or rinse water to dry on the paint and leave spots.

The people that use automated car-washes generally don't care or simply don't know any better.

 

[SeaJay's]

I think he has hit the nail on the head here. There is nothing worse than trying to apply wax to a hot surface...dries up immediately and is a PITA to remove.

Most people that are going to the automatic car washes just want to get their car clean for as cheap and least amount of labor. Which works for people who are working professionals. It's tough to find time to properly clean your car. But a lot of people are also not informed of proper technique etc.

 

[qaz393]

so whats a good way to cool down a car thats been sitting in the sun?? misting water onto it first?

 

[LegacyGT]

IMO it would use way too much water to cool it off (hundreds of gallons). I think your best bet is to park in the shade for a while then wash in the shade.

 

[VIP Reflections]

There are a few reasons why. 1. when surface is hot, the dirt, dust and grime gets kinda baked into the paint making it harder to loosen it up by pre-rinsing. the point of initial rinsing is to loosen up and rinse off excess dirt before scrubbing, so there is less of a chance of introducing swirls into the paint. so when hot, the dirt is more stubborn. not what you want when washing

2. the sun or a hot surface dries up suds. again, not what you want. especially if your trying to be quick about the wash doing a few panels at a time. washing in the sun, you have to be very quick to avoid this

3. Water spots... if your using hose water from your home or shop, depending where you live, the water has minerals and deposits that can be harmful to a clear coated surface when dried out by heat or sun.
so if you wash without drying right away, you will be polishing out water spots after the wash lol.

Now, take that 80% of peoples cars who go to the automated car wash with the sun been beating on their car all day, and compare their car to mine or my customers cars. Night and Day... Swirl city V.S the perfect swirl free finish

best time to wash your car, 6AM or 6PM

 

[maluminas]

IMO it would use way too much water to cool it off (hundreds of gallons). I think your best bet is to park in the shade for a while then wash in the shade.

I usually use no more water than what i would use with the first rinsing step (to remove loose dirt). This doesnt make the surface cool, but it cools it down enough that the soap/water wont dry on it. By the time im done washing, the water coming out of the hose is ice-cold and the rinsing step will bring the surface temp well below ambient. The hood might still be warm since the engine block can store a lot of heat, if thats the case i dry it first and start the next steps at the back of the car.

Of course i do all of this in the shade. If it was done in full sun then yes you would need to constantly keep the car wet, but then you cant to much work on it... lol

 

[Ted S.]

From my understanding, heat makes the paint softer and much more prone to scratches and swirls from contaminates.rops:

 

[LegacyGT]

I usually use no more water than what i would use with the first rinsing step (to remove loose dirt). This doesnt make the surface cool, but it cools it down enough that the soap/water wont dry on it. By the time im done washing, the water coming out of the hose is ice-cold and the rinsing step will bring the surface temp well below ambient. The hood might still be warm since the engine block can store a lot of heat, if thats the case i dry it first and start the next steps at the back of the car.

Of course i do all of this in the shade. If it was done in full sun then yes you would need to constantly keep the car wet, but then you cant to much work on it... lol

IME with a black car, black interior in direct noon time sunlight it is impossible to keep cool with water, that's what I was going on. A lighter colored vehicle would probably be less problematic, I guess I was just thinking worst case scenario.

 

[rott3np3anut]

I think your best bet is to park in the shade for a while then wash in the shade.

I think that's definitely the best way. What worries me more than getting water spots is that the cool water will make the metal contract. If you do it a lot, it could potentially crack your paint.

EDIT

A lighter colored vehicle would probably be less problematic, I guess I was just thinking worst case scenario.

I just realized I was doing the same. Although my car isn't black, it is relatively dark and really soaks up heat from the sun. But, even if I had a light colored car, I would just let it sit for a while to cool off.