What happens to old wax?

[lasthope05]

I'd think abrasion from washing/drying and environmental factors play the biggest role. I think we aren't taking into account just how miniscule a "layer" of "whatever it is you use on your paint" really is. It probably doesn't take much to "wear it off."

You just hit it on the dot. I believe it is the environmental factors that effect wax and sealants. Friction abrasion with driving the car and also factors like dust and dirt in the air/wind slowly but surely abrade away at what protection there is on the car. Also we all know frequent washing also dramatically reduces the LSP's durability.