MDO PLYWOOD

[Paulyboy]

This is only my 2nd or 3rd post on this website. I have a suggestion that may or may not have been discussed previously. I'm planning on one day building a teardrop trailer. One thing I learned years ago while supplementing my income with the occasional free lance sign painting job was the MDO plywood. This plywood has a permanent paper overlay and is constructed to be used as sign material outdoors. It's durable, indestructible ( moreso than regular plywood), and can be had with the overlay on one or both sides.
I've also used this in some of the industrial furnishings I've made. The advantage this has is the fact that it is paintable as is, and you can really achieve a very high gloss paint job if desired. As I stated, since it's an outdoor substrate, it'll last as long as the highway signs you see, because most of them produced at least thru the late 90's used this stuff. It's about 10% higher than regular plywood, but a decent supplier can also supply it in 5X10 foot sheets as well.
Hope I've helped.

[SteveH]

What about the weight? Isn't it a lot heavier?

[GeorgeTelford]

MDO, or medium density overlay, it's engineered plywood with a resin treated fiber applied to both faces. This gives an extremely smooth finish that is easy to paint. In addition it's rated for exterior use, which means it is safe from the elements, insects, or other outdoor hazards, making it a perfect choice for the new deck or porch or even teardrop !!



http://www.bobvila.com/TipLibrary/Subject/Framing/Wood/0299-MDO_Plywood.html

It weighs 75Lb for a 8 X 4 X 3/4" thick Sheet, so the weights only fractionaly higher.

Paint finishes on MDO are up to three times more durable than the same finish applied to ordinary plywood.Ideal for Painted Signs: In many instances, overlaid MDO plywood has proven a more durable sign material than metal. MDO plywood is resistant to the elements with no danger of rust or corrosion.

Edit to add sheet thickness to weight

[Paulyboy]

George, thanx for the vote of confidence. This is really great stuff. The other advantage it has over regular ply is that since the paper is bonded to the outeside, any machining you do to the ply, as in routing, cutting, etc., will have less (as in almost none) tearout around the edges.

[demtears]

Can MDO be found at home depot or any other building supply store? I have never seen mdo at home depot in canada.

[shil]

I'd found 3/4 coated both sides 4 x 8 at Rona. It was sold out when I went to pick it up, I ended up using paint grade maple. It is available.

[SteveH]

I found MDO at a plastic supply place (they sell it to sign companys) and at a specialty veneer lumber yard.

[DestinDave]

I've always thought they were the same but maybe not... Is there a difference between MDO and MDF? I've heard people refer to Medium Density Overlay and Medium Density Fiberboard as if they were the same horse... Dave

[shil]

MDO is plywood with a paper overlay. MDF is made from dust. They have nothing in common.

MDF explodes if it gets wet, it should never be used to build anything that might be used outdoors. It's great for building cheap furniture, the stuff you see on 'Trading Spaces' and those other fictional how-to shows.

[GeorgeTelford]

Hi Shil

Thats a little unfair on MDF, its actually been used to make bathroom furniture including bath panels. If its sealed correctly and painted it is water resistant.

Way to heavy and not my cup of tea.

[shil]

To be fair, I use MDF a lot. It cuts, finishes, and paints up just swell, and it's cheap. My point was that it's NOT the same as MDO.

[ralaco]

This is a topic for Doug Hodder, as he worked in the sign business many years and could talk about the good and bad of using medium density overlay.

Raul

[rwhitley]

Hey guys, I have been reading the posts and have started my tear drop project. I was considering the MDO, and I was curious as to how well it will hold a screw. Particle board doesn't hold a screw well even though you can use a special thread screw.

[GeorgeTelford]

Hi RWhitley


MDO is actually a plywood not any kind of particle board and will hold a nail just like any plywood, if you want to do a good permenant job always pilot and shank a screw in, this means using 2 different drill bits, the pilot should be the correct size for the stem of the screw and should be drilled through both pces of would to within a couple of mm of the total length of the screw, The shank should only be drilled through the pce of wood that is being attached and is slightly wider just under the size of the plain part at the top of the screw.

Reading through that description makes me wince, I know exactly what I mean, but my descriptive powers leave a lot to be desired. I will trawl and try to find a description that is clearer and hopefully with pictures too.

And yes I have been has guilty as the next man of driving screws in without any kind of pilot.

[GeorgeTelford]

Hi all

Here is the picture

and here is the description by someone with far better descriptive powers than I

http://www.woodworkingtips.com/etips/etip052600ws.html