A freshly waxed car tends to make water bead up on the surface of its paint finish. Ditto with a brand new car that has a paint finish with clearcoat or clear coat over it.
The beading effect because wax is hydrophobic. It's the same effect you'd see on umbrella fabric, which makes it perfect for weathering storms or heavy downpours.
The water slides off of the paint rather becoming absorbed by it, which can lead to corrosion of the metal underneath in the long run.
This is especially true of acid rain, which contains quite a number of contaminants and an unfavorable pH balance that could make short work of any unpainted car, turning its body into a rust bucket of sorts.
Hydrophobic Wax Is the Way to Go Against the Elements
- Why Is Wax so Hydrophobic? Wax repels water because it's water's polar opposite. It's like a pasty version of oil, which is also hydrophobic until you add soap over it, allowing oil and water to mix. Water is made up of molecules with the opposite polar charge that allows it to get attracted to metal and dirt. When rain falls on a car that's unwaxed, it tends to spread out more easily than hot butter on toast. This results in clear coat finish destruction and metal body corrosion in the long run.
- Wax Is Nonpolar: A waxed car repels water because wax molecules are nonpolar. If the car has a coat of wax protection, water has nothing to stick unto but itself, hence it beading like on umbrellas or certain hydrophobic plants. Its scattering into round beads that rolls off of the surface of a vehicle can also be seen in most modern cars with clearcoat on them. Adding wax to clearcoat paint finishes therefore results in double the protection.
- How Does Car Wax Protect Against Sunlight? Car wax is able to protect your car from sunlight, specifically ultraviolet rays, through its reflective properties. To ensure superior sun radiation shielding, you should get synthetic wax products made of silicone or natural wax derived from palm leaves for best results. The reflection or deflection of the sun is akin to putting suntan lotion over your car, to be quite honest. There are even waxes with extra polymers and oils specifically formulated to make them more reflective.
- That Shiny Look Is There for a Reason: A shiny car, as opposed to a dull car, isn't only pretty to look at. It's also a reflective car that makes the damaging UV rays bounce off the surface like a mirror. That shine is also an indicator that dirt and water aren't able to stick unto the painted finish that would normally make it corrode and peel off, revealing the rust-vulnerable metal underneath. A dull-looking, waxless car is more likely to absorb ultraviolet radiation to boot.