So, for years and years I have been refinishing exterior stained doors that have faded or started to show some wear. I sand them a little, touch up stain where required and clear coat them. I used to use the Sikkens Cetol Door and Window product for the clear coat (oil based) but recently have started using the Modern Masters MasterClear Supreme (acrylic). This last door I did for my dentist was one of those factory finished fake grained stained doors (like Therma-Tru, but some knock off brand) and a couple of days after the door was done, some white cloudy areas started to appear under the finish. The tech guy at Modern Masters says this is moisture trapped under the finish which I supposed I already knew, but am baffled as to how that could happen, being that the door was completely dry when I left and crystal clear. The guy also said that I should be removing the factory finish from the door (because it's oil based) before topcoating with their product. It says nothing about that in their technical data sheets and I would have never considered it necessary to completely remove the current coating. I'll stick with the oil based Sikkens topcoat if that is really the case. What do you guys think?