no serious.... what i do is apply by sir brush .. or paint brush .. johnson's clear .. its a floor polish .. its water based and ypu can get in most supermarkets ....
brush on .. let dry 12 to 24 hours ... apply decal ... and then put a layer of matt or satin varnish on top .. then bobs your uncle done!
once done the decla becomes alost indestructiblae ....
its so easy to do .. i belong to an ipms group of modelmakers and we meet once a month for a model makeing day ..the aircraft builder swear by that methord .. and the results are brill ..and a lot cheaper and easyier that othere systems !