There is a lot of confusion out there on what “protected” paint looks like. Often times it is associated with those really high contact angle beading photos, and for good reason. That means there is a strong hydrophobic layer on the paint, which in turn helps with “self-cleaning” where contamination doesn’t stick to the paint as well so water will push it off.
However, beads do not mean good protection. Many things are hydrophobic. Oil, for example is extremely hydrophobic, you could slather some coconut oil on your paint and get some insane beading photos. Obviously that wouldn’t provide good protection, wouldn’t last and would attract dirt like crazy. Hydrophobic means a tendency to repel water, thus creating the beads. Most car protections bead water as it is common sign of protection.
Then, there is water sheeting. This is where a surface is more hydrophilic, an attraction to water, so the water has a very low contact angle, yet the water glides off the paint in large “sheets”. The thing with a hydrophilic surface is it actually will keep more water off the surface as to create beads there has to be some level of tension holding it in place. These types of coatings are more often used in commercial and medical industries. You can also have a hydrophobic surface that sheets water when the beads come together to form one water mass, think of when you watched the rain drops race on the window when you were a kid and two would link up to form a super water drop so your wins the race. Everyone did that right?
Ok, so what does this all mean? It means that beading does not mean protection but is usually a good indicator. Water sheeting or beading does not mean one is better than the other. You want solid protection and depending on the chemical formulation the surface makeup may be one or the other. As long as the protection does not easily wash away and makes the paint easier to clean, you know you have good protection. then the longevity of it is what makes it even better. This is why coatings are so popular, and expensive. Automotive paint protection is the resistance to UV rays, chemicals, etc over an extended period of time, not the ability to rain or disperse water.
See below the left photo is a surface that is sheeting water where the left is beading water. On a horizontal surface it may look like the left has no protection.
When turned vertical all of the liquid on the left glides off the surface leaving it dry, where the right is still holding tension of the beads.
