“Always wax your car in the shade, out of direct sunlight”
If you’ve ever waxed a car then I’m sure you’ve heard this before. Every different wax product I’ve ever used has had something similar to this on the label. In fact, you could hear a dozen different tips for waxing a car from a dozen different sources, but every one of them worth their salt would tell you to make sure that the car is in the shade. But the question then becomes, why?
Why would it make a difference whether the sun can see my car or not when I put wax on it? There are really several reasons for wanting to keep your car in the shade. The most widely known reason is that the sun can effectively bake the car wax right on to the surface of your vehicle, making it much more difficult to remove. This is really an inconvenience more than anything else, but still something that you’d probably want to avoid.
More seriously, the longer a car sits in the sun (especially a dark colored car), the higher its surface temperature will become. This can have the effect of softening the paint, making it much more susceptible to light scratches, swirl marks, etc. For this reason, even if your car is in the shade, be sure that the car has some time to cool down before you start to work on it.
Another problem that a hot paint surface can cause is that certain oils in carnauba based waxes can evaporate when the (carnauba) wax comes into contact with your car. Also, carnauba has a melting point of about 180°F. It is entirely possible that a black paint finish left in the sun all day could exceed this temperature and essentially melt your wax before it gets a chance to adhere. In either of these cases your wax won’t last as long as you’d like, if at all, and your time spent waxing your car will have been for naught.
Had any problems with waxing your car in the sun? Let us know about it in the comments!