MDO vs veneered ply for painted panels

[Rob Blaustein]

After hearing how great a surface MDF is for painting I bought some MDO for a panel that I have to paint to match some cabinets. My reading suggests that we are best with an oil-based primer and oil-based paint to avoid wetting and swelling the MDF veneer and to get a nice finish (we will be using a brush since we don't have spray equipment). But now I'm wondering--does properly painted MDO look better than properly prepped/primed and painted veneered plywood? I ask because the MDO was pretty pricey and it also caused me another mild headache--the panel I have is 1/64" over 3/4" and I was going to edge band it with some solid 1 x popler which is dead on at 3/4 and the lip is noticeable.
--Rob

[Wayne Cannon]

You use both "MDO" and "MDF" in your posting. I don't know if that was intentional.

MDO (Medium Density Overlay) provides an excellent surface for painting and a good exterior glue -- in fact outdoor signage is one of its primary applications. It has a resin-treated fiber overlay surface and is quite water resistant in its raw form. It can be readily primed and painted with water-based products with excellent results.

MDO: http://www.plumcreek.com/downloads/productInfo/MDO.pdf

MDF is a significantly different animal. Attached is an article on finishing MDF (that uses water-based primer and finish products, by the way) focusing on treating MDF's cut/machined edges, etc., for a uniform finish.

MDF: http://www.josephfusco.org/Tips/MDF.html

[Rob Blaustein]

Wayne--I used both intentionally but perhaps errantly. I thought MDO was simply plywood core faced with a "veneer" that was essentially MDF, and therefore assumed that whatever rules applied to painting MDF applied to MDO. I assumed that the "medium density" part of each name referred to the same material. Is this wrong?

[Jim Becker]

No, the "medium density" is not referring to the same thing for these too products, more or less. MDF is a compressed fiber product. MDO is a paper/resin covered exterior plywood. (Typically used for highway signs, etc.)

Rob, MDO is a good choice for painting, but the wood grain may telegraph through the paper surface...and since it's exterior rated stuff, the wood underneath isn't as smooth as cabinet grade plywood. MDF will give a smoother end-result after painting, at least on the factory surfaces. (and once you work and fill the cut edges, you can achieve a smooth surface there, too)

[Rob Blaustein]

Thanks for the clarification Jim. So if you had to choose a material for a painted panel for a kitchen (to frame a fridge and support a small cabinet over the fridge) what would you use? I narrowed it down to MDO or MDF and ended up going with MDO though it was twice the price at my local lumber yard as the birch veneer ply at HD which doesn't carry MDO.

[Jim Becker]

Depends upon the design, Rob...but I'll tell you that I actually did use 3/4" MDF for the end panel for the fridge enclosure in our kitchen with 1/4" poplar overlays to simulate Shaker 15º bevel edge rail and stile design that is throughout the kitchen. It does tie into the cabinet over the appliance, but that cabinet is also attached to the wall and ceiling. The visible edge was banded with solid poplar. All of this "embellishment" was done prior to painting to match the kitchen cabinetry.

[Rob Blaustein]

Depends upon the design, Rob...but I'll tell you that I actually did use 3/4" MDF for the end panel for the fridge enclosure in our kitchen with 1/4" poplar overlays to simulate Shaker 15º bevel edge rail and stile design that is throughout the kitchen. It does tie into the cabinet over the appliance, but that cabinet is also attached to the wall and ceiling. The visible edge was banded with solid poplar. All of this "embellishment" was done prior to painting to match the kitchen cabinetry.

That's a very interesting idea. I will probably PM/email you about this approach since I need to make some end panels and this might be less work than making rail and stile Shaker doors.

[Doug Shepard]

Hope I'm not derailing this thread too far, but would MDO be a decent choice for a doghouse (painted)? Would it hold up to weather any better than standard exterior ply?

[Wayne Cannon]

Although I've never seen any sign of grain telegraphing through MDO, I believe MDO can have interior voids and it uses only a few thick plies (just like ACX plywood). MDO edges are pretty coarse. I would not consider MDO for kitchen panels (I use a lot of it for shop cabinets, though).

In other words, I think of the two, MDF is definitely your best choice.

[Wayne Cannon]

I think MDO would make an excellent dog house, painted or unpainted.

I used unpainted, untreated, unsupported, raw MDO plywood for "temporary" exterior gates with an unshaded southern exposure. After three years of hot sun, unprotected wind and rain (no snow or freezing -- only a light frost), it was still as good as new -- no signs of weathering, delamination, warping, or anything. There was only a very slight shift in color.


MDO is significantly more weather resistant than any exterior plywood I've ever used -- they've all delaminated from deterioration of the wood plies. In fact, before the "temporary" MDO gate, I had even more "temporary" CDX plywood gates for a year that bowed/warped an inch across their three-foot widths ("lumber yard" CDX, not "big-box" CDX -- but that's as refined as I know). I've also never paid as much for any exterior plywood as for MDO, though!