This may sound a little odd but it's for a job that I have been talked into. Its for an internal sliding bathroom door that is painted with matt emulsion. For reasons of colour and nagging I need to maintain the coluor but protect it from steam, light splashes and damp handprints. SO, can anyone advise on a water=based varnish that I can paint on, thus protecting both the matt emulsion and the door itself? Thank You !