Let me answer right off the bat here…if you’re painting with latex paint over anything that already has an oil-based finish on it (whether it’s paint or stain or varnish or polyurethane), and you’re not intending to do some sort of dry brushing, let-the-original-finish-show-through type of finish or any other specialty finish, then the answer is absolutely, unequivocally “YES”!!!
But what if you’re painting with an oil-based paint over an existing oil-based finish? Is primer really necessary then?
I’ve always believed it was…that is until I had a conversation with a professional painter (who’s been doing this for many, many moons) who said it wasn’t really necessary. He explained to me that oil-based paints contain solvents that cause them to actually bond into the previous finish, rather than just sitting on top like latex paints do.
Hmmmmm…intriguing! So I decided to put it to the test.
Remember my two dining chairs that I decided to go ahead and use in my breakfast area (after months of searching for chairs on Craigslist with no success)?
After I removed the seats from both of them, I spot sanded each of them (they were pretty dinged and scratched), and then I primed ONE of them with oil-based primer…
I skipped the priming step on the other chair. Then on both chairs, I painted two coats of oil-based paint.
So, can you tell a difference?
Not at all. They look identical.
But of course the real questions is…are both finishes equally as durable?
Well since they were only painted one day ago, and paint takes a few days to really cure, I didn’t want to be too rough with either of them and potentially ruin my work. But I will say that I used my fingernails and scratched back and forth over the finish with moderate pressure on both chairs, and neither of them chipped or scratched. The two finishes were equally as durable.
So what does this mean? Have we all been wasting our time with primer?
I think my answer to that would be “sometimes”. In some cases, I think primer is still a great first step.
Consider this: Let’s say that you’re painting your kitchen cabinets in your moderately-sized or large kitchen. You know that the cabinets will take two coats to cover completely.
You can use your oil-based paint (which costs anywhere from $40 to $50 per gallon) for both coats and take the chance of running out and having to purchase more paint to finish the job, OR you can use primer tinted to match your paint for your first coat (at the cost of about $18 per gallon), and follow up with one coat of your paint and probably have plenty left over to keep on hand for future touch-ups when the need arises.
I’ll also add that there really is something about primer that “seals” the previous finish, so if you’re dealing with something that has stains that may bleed through, knots in the wood, or the previous finish has worn down to bare wood in areas, then I definitely would NOT skip the primer.
But on smaller projects, like chairs, end tables, and similar objects, this is definitely something to keep in mind!