I can't speak to layering of this product, however here's what I've been told by some:
Sealant, and wax for that matter, are formulated to bond to the surface of the paint and then cure. It's also formulated to then repel surface contaminants like water, dirt, etc.
So, as a result, most don't layer effectively. They either repel the 2nd coat or with many they don't build higher - they just push each other around.
Now, I've seen people layer products and it seems to create longer lasting results. So as a result, I have no idea what the truth is
