Hi gang,
Layering has much to do with the solvent content and properties of a product, as well as the ability (or inability) of that product, once cured, to redissolve back into that solvent.
i.e. Surf wax has a low solvent content, so it layers easily--that's what it's designed to do.
By the way, I prefer the carnauba look on my black Benz as opposed to a polymer look. Gives the car a rich, silky glow rather that a bright dazzling shine. However, I do like the way a poly looks on my silver Nissan Quest. Both work for me!
Aloha,
Keoni