Do you guys have a problem with soft finish when using poly out of rattle cans? 3 months after finishing my guitar with satin Cabot's exterior poly (3x triple coats) I can still dent it with my fingernail if I press hard. It's not woefully soft, just softer than some of my furniture finished with a poly varnish (brushed). Is it just because the finish is too thin, or is spray poly a bit softer?