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Is primer really necessary with modern paints?

Painting without primer

One of our readers asked why we'd bother to use primer since modern paints are, at least to some degree, self-priming. I answered that, in my limited experience, one coat of paint doesn't cut the mustard unless you're painting over existing wall Repaintingpaint. If I'm going to have to apply two coats anyway, why not start with a can of cheaper primer for phase one?

To illustrate my point, I pulled out our dinner table, which I painted with a single coat of paint (no primer) a bit less than a year ago. Tables see relatively hard wear, and eleven months was long enough to rough up the surface so bare wood was showing through in spots. Time to paint again!

The big question will be --- which surface looks better at this time next year, the table with two coats of paint or our bookcases with one coat of primer and one coat of paint? Let's see if I remember to report back in January 2018.



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I love to paint, number # primer is a sealant, which penetrates the wood. Sealing it allows the paint to adheres to the surface. Most paints today says paint and primer. However on bare wood you need to go with primer then paint.

Today's paints with primer do cover surfaces better than before covering marks, scuffs, without a second coat.

Comment by Rose Hamilton Mon Dec 26 10:23:05 2016

As often with such questions, the answer is "it depends"; on what you're painting, which paint you're using and what you are trying to accomplish.

General guidelines for any paint (or glue) are that the substrate should be dry and free of oil/grease and dust. Surface preparation is key to a good paint job. For the best adhesion I tend to de-grease, sand and de-grease again.

Beyond that it very much depends on the substrate. Aluminium generally has bad adhesion without a specialized primer. MDF which is 50% air by volume is like a sponge that can suck the water/solvent out of your paint before it is fully cured. In this case using a sealant saves on expensive paint and makes the paint work better. If you want to smooth a rough surface, that is best done with a filler primer. On soft wood, the underlying wood might fail allowing the paint to flake off. In that case a good epoxy or polyurethane could create a hard surface layer.

And so on and so forth.

Comment by Roland_Smith Mon Dec 26 11:15:32 2016

Ha! Got you to do an interesting experiment.

What about staining and polyurethaning? I don't think those last as long unless you put beaucoup layers on like I did when I "repaired" a kitchen counter by overlaying it with a board 1/2" deep and waterproofed it with 10 layers of polyurethane. Even then, a hot pot burned a hole through the polyurethane and I had to repair the hole. Because food and such would be in contact with the wood, I didn't want to paint the "new" countertop and I liked the look of the bare wood which is why I opted for polyurethane.

Comment by Nayan Mon Dec 26 11:18:18 2016
@Nayan: Did you use a 1-component polyurethane? For the most resistant coating you probably need a 2-component polyurethane or epoxy. Those can give a glass-like finish, and should resist a pan of hot water for a short time. A pan of hot oil is probably too much for almost any organic surface coating.
Comment by Roland_Smith Mon Dec 26 15:36:43 2016
Roland, I used Minwax fast-draying Polyurethane clear gloss. I did put ten (10) coats on the wood on the counter near the sink, but only five on the counter near the stove because I have a old cutting board that I put hot pans on when needed. You're right about any coating not being able to deal with hot pans and that's probably the mistake I made. Now I don't do that anymore! :)
Comment by Nayan Mon Dec 26 17:34:13 2016