Can I apply more than one layer of Liquid Luster?

Of course!

That's one of the great things about Liquid Luster. You can put one layer of Liquid Luster on your sandblasted surfaces to fingerprint proof the surface and keep as much of the sandblast appearance as you want or you can apply multiple layers to move the surface closer to translucence. 

It all depends on the aesthetic you are trying to reach.