warping wood with latex paint

[Michael MacDonald]

I think I know the answer to this, but want to get a second opinion... I recently finished making a poplar desk--a base with typical apron and drawers, desktop to be attached with wood buttons, and a large hutch that attaches to the desktop with sliding dovetails.

I wanted to make it from cherry and finish it with oils, but the request was for white paint... so all poplar.

I started painting the desktop with kilz premium primer and put two coats of latex paint (ben moor cabinetcoat) on the bottom side of the desktop. Both are water-based products. And I discovered that the primer and paint had warped the top badly. I let it cure, turned it over and finished the other side, and got luck--warped right back almost perfectly. A little bit with each coat. I got lucky?

So I am thinking I should use shellac sealcoat for at least one layer before touching the rest of the desk with latex again. is that correct? Should have done that to begin with. It would be seriously sad if I goofed it at this point. Will one sealcoat layer be enough?

[Rich Engelhardt]

Will one sealcoat layer be enough?

Kill two birds w/one stone and use BIN instead.

[Scott Holmes]

AND lose the latex, (wall paint) if that's what you are using. Use a harder 100% acrylic paint.

[Michael MacDonald]

Rich - Good point on the BIN. I looked that up, and it is a better idea. Didn't know it existed--pigmented shellac. I will use that instead of normal primer. Glad to not stress over priming the other parts now... certainly I would have had a problem.

Scott - thanks for your suggestion. I went to a Benj Moore store and asked what they recommended. They provided me with Insl-x CabinetCoat, which is a "urethane acrylic" with satin finish. It is a water-based enamel paint, but I think it fits your recommendation. Is there a better product you have in mind? (note I first went to HD, and they just suggested I use a wall pain with gloss finish... I had the suspicion that was not right, and I hope the Ben Moore guys did not steer me wrong.)

So far, I have finished the table top, it appears flat enough right now, so I dodged that bullet. I think the surface is usable, but my judgement on this is not from experience.

Regards,
Michael

[Rich Engelhardt]

I first went to HD, and they just suggested I use a wall pain with gloss finish

LOL!..love the typo...& I agree, wall pain is a good way to put it .
Anyhow - they may or may not of been correct@ HD.
Lot's of things have changed on the last year or so.
More and more of the "latex wall paint" is going over to a 100% acrylic.
The Behr Premium Plus Interior line, which is all "latex wall paint", is all 100% acrylic.


Tremendous strides forward have been made in the last few years in the area of waterborne coatings.
A lot of "changes" in the wording on labels/the way paints are marketed is also taking place.
The word "latex" appears to have been recently added to quite a few materials recently.
I just ran into this with a Sherwin Williams product.
I can only speculate that the marketing machine wanted "latex" on the labels to let people know it was "soap and water cleanup".

Just a short time ago, the advice to avoid "latex wall paint" was a 100% valid recommendation since other resins than 100% acrylic were the norm.
Recently though, more and more and more products are coming out with 100% acrylic or an acrylic hybrid.

What I find a little bit odd is that a Benny Moore dealer would recommed Insul-X over Ben Moore Impervo?

[Michael MacDonald]

Not sure why they didn't recommend their own product... perhaps the dealer thought CabinetCoat brushed better. I do not spray at the moment and told him I would be brushing, and needed the right product for a writing surface. He carried it and was able to tint it, so it is not like he sent me to another retailer. So this isn't made by Ben Moore? I didn't realize that.

Thanks for your comments. Just for fun, here are some pictures--only the writing surface is finished so far. Sliding DT to attach the hutch to the top. hand-cut DT for all four drawer corners. Sliding sub-drawer in the sid drawers. I didn't carve the top detail--it is purchasd and applied.
IMG_3208.jpgIMG_3210.jpg

[phil harold]

You got lucky
paint or finish all sides at once, will reduce warpage on flat panels or doors

[Rich Engelhardt]

Just for fun, here are some pictures--only the writing surface is finished so far.

Looks great! Post more pictures when it's all done.

[Michael MacDonald]

Finished product pic. LED light under hutch. Kitty cat drawer knobs. I regret now using poplar... too soft. (nice and light, though.) Paint may be OK--too soon to tell. The paint was tough to do by hand, though... I don't want to do another coat, so I hope it holds up

I should also add--I love BIN... using it on other things now. Tossing out the water-based sealer.

2012-09-06 07.11.34.jpg

[Jason Roehl]

No luck involved at all. I doubt any of the primer products mentioned form a true vapor barrier in one or even two coats. So, even primed, when you paint one side of a panel with a waterborne product, some of the water in the paint will seep through the primer on that side, causing it to expand slightly. Since the other side is still dry, the panel will cup toward that side. As you found, painting the other side brought the panel back to flat--when that second side absorbed moisture from the paint and expanded.