I know one must use primer on raw wood for good performance of the paint that ultimately covers it. My question is - what is in primer that does the "priming" ? It looks for all the world like regular old paint, so why don't they just put the stuff that's in there right in the paint so we can just paint without multiple steps?
Yeah, I know that to pro painters this is probably a dumb question, but I'll bet there are others out there who wonder about that every once in a while too - so flame if you must, but I'm just wondering.