Its LTP tile sealer and colour enhancer so it seems like a topical product, although it does say it allows the surface to breathe.
When I said window effect, when i put the sealer on it seemed to be wetter around the edges but I had another look tonight now its dry and I cant notice that effect. I did however notice what you said about wax on the surface because some of the mosaics have a brown tint. I guess it must have hapened when I stacked them out of the way before laying them. This was after I had sealed them.