Will paint protect wood from moisture?

[Tim Andrews]

Hello all,
I want to build a small “caddy” to hold our electric toothbrushes and clean up the cords. Our bathroom is contemporary, white with color accents, so I want to keep the caddy white. My plan is to build it with lightly figured solid wood or MDF and paint it white to match the decor. I would prefer spraying for a cleaner look. I’m wondering if multiple coats of spray paint (after priming) will be sufficient to protect it from water damage. Anyone have experience with this? Thanks!

[Lee Schierer]

Yes and No, it depends. Enamel type paint will protect against casual splashing, Latex will not. If it sits in water or has water on it for extended periods the paint my let water penetrate. I would use several coats of brush on paint to get a thick coating. Make sure the end grain and any joints are well covered. I would recommend feet on the base so water doesn't linger under the base. Any nicks or chips will allow water to get in.

[John TenEyck]

Yes, paint (pretty much any paint) will protect it from water as long as you have a contiguous film. I made a sink base for my half bath out of MDF, primed and painted with BM Advance. It's about 4 years old now and looks new.
John

[Maurice Mcmurry]

Protect yes, waterproof no. Some specialty paints will waterproof. Products like Palgard and Gluvit create an impermeable film. Single component enamels, latex, acrylics, etc. create a permeable film. Multiple coats of marine enamel can become waterproof.

[John TenEyck]

To further clarify, paint is waterproof but it is not moisture proof. That is, it will keep liquid water out but let water vapor transfer through. For your application primer and paint should work well. It has for me.

John

FWIW, most all finishes behave as described above.

[Tim Andrews]

Thanks gentlemen, I appreciate your replies!

[roger wiegand]

If you're really worried about it you might make the piece out of cpvc (eg Azek, or similar). That won't absorb water or moisture and hangs onto paint even when pretty wet.

In most bathroom situations painted wood will be fine. I'd not use MDF anywhere water is a possibility. It will absorb moisture and swell.

[John TenEyck]

If you're really worried about it you might make the piece out of cpvc (eg Azek, or similar). That won't absorb water or moisture and hangs onto paint even when pretty wet.

In most bathroom situations painted wood will be fine. I'd not use MDF anywhere water is a possibility. It will absorb moisture and swell.

Not if it's primed and painted well, as I mentioned above. My half bath sink base is living proof.

John

[Scott Clausen]

Nothing lasts for ever but if you seal the end grain it will close the pathway that water formally went up the tree. Of course that will interfere with a glue surface and maybe between the glue and some caulk you can keep those water droplets at bay. Might help to shake off moisture well before dropping them in.

[roger wiegand]

Not if it's primed and painted well, as I mentioned above. My half bath sink base is living proof.

John

OK, I could dig up pictures of both bath and kitchen cabinets I demoed that self-destructed despite paint (no notion of whether it was done "well", and therein may lie the rub!), also providing living proof of a sort. Where does that leave us? I'll be happy to continue to use less moisture sensitive materials in settings that might involve water. I'll admit I don't trust my, or anyone else's, ability to create impervious barriers with paint. I've just taken apart too much rotted stuff over the decades to think it's a good bet. And I don't dispute your evidence at all, I'm just not sure it can be generalized. I'm sure you're a better painter, and certainly more knowledgable about finishes, than I am.

[Mel Fulks]

The paint protects well IF the bark side of the board is the FACE SIDE. The heart side will peel and leave razor blade type pop-up grain .
Modern methods are good , except when they don’t have directions on how wood works.

[Maurice Mcmurry]

It is interesting to look a paint films through a microscope.

A good example of the limitations of paint is the very short life span of masonite siding. Even Colorlock (which was advertised to have an impervious factory applied paint) fails terribly when exposed to rain.

[John TenEyck]

Yet highway and business signs made of MDO last for many, many years. The key is to seal the edges well. Siding that is cut for installation eliminates the benefit of any factory coating unless it is resealed prior to installation. Many folks fail to do that, hence the short life.

John

[Maurice Mcmurry]

Yet highway and business signs made of MDO last for many, many years. The key is to seal the edges well. Siding that is cut for installation eliminates the benefit of any factory coating unless it is resealed prior to installation. Many folks fail to do that, hence the short life.

John

Exterior fiberboard used for signs, skateboard ramps etc. is a very different product than wood or regular MDO.

Colorlock used a H channel to protect the ends. The failures and resulting class action lawsuits have to do with general over all failure.

[mark mcfarlane]

I sprayed a couple coats of SW rattle can oil primer on some 1/2 BB plywood 3 years ago to do a temporary shower repair. It has held up so well that 3 months turned into 3 years. No sign of water penetration, just a little yellowing. Edges were coated in silicone to adhere it to the shower wall.