I've heard that if the first couple of coats are "misted" over the decals, they should be okay. The rumor about TS-13 decanted ans spray through an air-brush is just that, a rumor. I've never "cleared" over decals as yet as my models don't need to be protected at all. I build them, show them at a couple of club meetings and an NNL, and then put them in my display case. I have a model that I've built in the early 80's with my first BMF job and it still looks great today. I know, some builders like to clear over BMF as well. I clear my models before any decals or BMF.