Painting - Water or oil based primer

There appears to be some debate on the use of oil-based or water- based primers on exterior trim... what are the thoughts here? Apparently old-schooled contractors use the oil-based, but the current thought is that the water- based primers are just as good nowadays? Yes? How about on ext. rails and balistsers on a porch? Thank you for your thoughts.

No doubt this debate will rage on. I am a middle-schooled paint and paper contractor but getting closer to old school every day and treat every project on a job by job basis using both materials. New Work- The plus for latex primers aside from ease of use and cleanup is they allow the wood to breath and any moisture trapped in the wood is able to get out without causing blisters. In that I don't come across the trapped moisture problem much where I live I prime with oil primer because latex will not hold back saps and knots and by the time I spot prime all of these areas it is just as easy to go all over with oil. Also, pre-primed masonite tends to discolor if not primed with oil. Existing Work- Here again the oil wins out because I don't want the raw scraped areas to discolor and I feel that trapped moisture would have shown up as a problem by the time a repaint is needed.....Mike

Thanks Mike, for your reply. So it sounds like oil wins out unless there is high hummidity in the area... which we have very little here. We also have fiberglass collumns. I imagine we will call the manufacturer on how best to paint those... but what is your recommendation there? I was told at the ye 'ol paint store that I can use a "uniprimer" on both the raw wood and fiberglass...Yes? Oh, and another, I'm afraid stupid question. We have hardiplank siding, a cement composit... does that need to be primed? And would that use probably less paint than wood ?

Do check with the maker of the fiberglass products but I would say its safe to use the latex primer on those. Get the best primer you can buy from a pro paint store. Some of the paints at big box stores work well but the primers most often are thinner. The exception would be Zinsser products which are great. I used the 6 inch Hardiplank that produces a lapped siding on my shop and just put 2 coats of satin latex paint and it was fine for 6 years until I had a small fire that smoked it up a bit. I'm not sure but I think it has a primer on it from the factory and no doubt would take less paint on the first coat than wood and about the same as a second coat over wood....Mike

Mike,

Thank you. Yes, we are using the lap 6 inch Hardiplank as well. How did the Satin finish look?? I just got back from a Sher. Wm's and they were still pushing the latex primers unless in was on Cedar or Redwood. Hhmm....

Much appreciated for all your help.