Painting MDO Plywood?

[minuteman62-64]

Planning to use new MDO plywood for decking over the bow section of my boat. Original seats were MDO plywood, appeared to be painted with an oil based paint w/o primer. Held up well for 30+ years. I re-painted one of these with good quality oil based paint (with out primer) and that (applied over a well aged MDO surface) is holding up well. I can't tell if the manufacturer scuffed up the MDO finish prior to paint application.

I have also had excellent results using Rustoleum oil based paint, as well as the oil based paint I've been using on my boat, applied directly on regular plywood (w/o primer).

So, I'm wondering, when I paint this bow decking, with a brand new MDO surface, primer yes or no? Scuff the MDO surface prior to paint application? I should add, the guys who sold me the oil based paint I've been using (it is called "Aro-Plate II, SG" by Frazee) said no primer necessary over plywood as long as I'm not aiming for a smooth sanded surface.

Appreciate input, particularly from you guys with experience painting over MDO surfaces.

 

[Grub54891]

Re: Painting MDO Plywood?

Might be just me,but I would not have it within 30 yards of my boat.

 

[crabby captain john]

Re: Painting MDO Plywood?

might be just me,but i would not have it within 30 yards of my boat.

x 2 !!!

 

[minuteman62-64]

Re: Painting MDO Plywood?

Might be just me,but I would not have it within 30 yards of my boat.

What would be the issue? A lot of the aluminum boat manufactures (Westcoaster, Valco, etc.) routinely use MDO for seats/decks.

 

[Bob_VT]

Re: Painting MDO Plywood?

No need to prime. Good quality oil base and more then a single coat. I would actually do all the edges first then the surfaces.

The edges are the weak points for water to get in and wherever you drill a hole.

Keep in mind when original manufacturers used the MDO it was with a planned lifespan and not made to last "Forever"

Yep go with multiple coats of paint (Maybe add in a hardener) and have fun!

I hope the people who are afraid of it are not confusing the MDO with MDF (which is mostly cardboard)

 

[gm280]

Re: Painting MDO Plywood?

What would be the issue? A lot of the aluminum boat manufactures (Westcoaster, Valco, etc.) routinely use MDO for seats/decks.

Before redoing your deck with MDO, do you realize just how heavy that stuff is? I would go with a quality exterior type plywood route and save the weight. Weight is a true killer on most any type boat to get the power out of the motor. Just a thought...

 

[Grub54891]

Re: Painting MDO Plywood?

Agreed,mdf/mdo are different. I personally don't like either one. Mdo,harder to use staples if need be (for upolstry) , mdf,just rotten bad news,and as stated ^ heavier.
Grub

 

[minuteman62-64]

Re: Painting MDO Plywood?

Before redoing your deck with MDO, do you realize just how heavy that stuff is? I would go with a quality exterior type plywood route and save the weight. Weight is a true killer on most any type boat to get the power out of the motor. Just a thought...

I'll be using a little less than 1/2 sheet of 1/2" for my decking. ACX would weigh about 24 lbs. The same amount of MDO would weigh about 30 lbs. - a 6 lb. penalty. I'll pay one of my fishing buddies to lose 6 lbs. to make up the difference

 

[jigngrub]

Re: Painting MDO Plywood?

MDO is one of the best plywoods you can get for boat building.

I would sand the surface before painting, I don't like to paint on top of anything slick and shiny. Sand with 150 or 120 grit and just dull the finish, the paint will bond better. Paint the edges until they're completely sealed and closed up.

For your elevated you only need to paint the exposed to and edges, but it won't hurt to do both sides if you want.

 

[Bondo]

Re: Painting MDO Plywood?

MDO is one of the best plywoods you can get for boat building.

I would sand the surface before painting, I don't like to paint on top of anything slick and shiny. Sand with 150 or 120 grit and just dull the finish, the paint will bond better. Paint the edges until they're completely sealed and closed up.

For your elevated you only need to paint the exposed to and edges, but it won't hurt to do both sides if you want.

Ayuh,.... I Agree with All yer points, but Especially Sandin',....

Any surface that's gettin' Painted, needs Sandin', 1st,....

 

[minuteman62-64]

Re: Painting MDO Plywood?

Keep in mind when original manufacturers used the MDO it was with a planned lifespan and not made to last "Forever"

I just turned 73. How long does it need to last?

 

[jbcurt00]

Re: Painting MDO Plywood?

I just turned 73. How long does it need to last?

Until your grandkids are done using it :watermelon:

There might be plywood that is considered a 'better' alternative, that are likely more expensive, but there are LOTS of choices that are worse.

I used MDO for my recent transom fabrication & couldn't be happier w/ it. I will suggest that you use single sided NOT 2 sided. You only 'need' 1 side of the plywood faced w/ the paper. It should be the up side, and will sand nicely in prep for paint. It might also be referred to as 'Good 1 side'.....

 

[NSBCraig]

Re: Painting MDO Plywood?

Cant even think about using it. Some people on here started talking it up so i had to try it out on a job and learn about it. Everybody has a opinion and mine is not a chance.

Also wasnt it figured out that the stuff used by those builders was a special order item.

Transoms of mdo oh my!

 

[jbcurt00]

Re: Painting MDO Plywood?

Craig, your the only 1 I've ever heard that wasn't happy w/ MDO, for any use, marine or otherwise, and how great it is to work w/....

To avoid hijacking this thread, I'd love a PM w/ a link to your thread or info about how you used & the difficulty you had using MDO.

 

[Lone Duck]

Re: Painting MDO Plywood?

Cant even think about using it. Some people on here started talking it up so i had to try it out on a job and learn about it. Everybody has a opinion and mine is not a chance.

Also wasnt it figured out that the stuff used by those builders was a special order item.

Transoms of mdo oh my!

Well sir. I guess I am in a lot of trouble. I did my whole hull with 3/8 MDO With 3/4 MDO added to the flat bottom and 3/4 sheets on the stern. Hull is framed with 23 ft long 1x4 fir and 2x4 fir 1/4 sawn. all wood encapsulated with epoxy before paint. Paper side of MDO was not sanded just epoxy encapsulated and finished with epoxy paint. The MDO was paper one side. In my opinion it is beautiful stuff. But that is just me.

 

[jigngrub]

Re: Painting MDO Plywood?

Cant even think about using it. Some people on here started talking it up so i had to try it out on a job and learn about it. Everybody has a opinion and mine is not a chance.

Also wasnt it figured out that the stuff used by those builders was a special order item.

Transoms of mdo oh my!

Let me guess, let me guess... you tried to use polyester resin on a phenolic (epoxy) coated plywood and it didn't turn out too well?

 

[Watermann]

Re: Painting MDO Plywood?

I'm for the sand it first. Actually I like to use a wire brush with a handle on it to lightly scuff the surface, then run a palm sander with 180g to knock the loose stuff off and finish by wiping off the dust. I do however always use a good oil based primer as a base coat, I think it just makes the final product look better too.

 

[minuteman62-64]

Re: Painting MDO Plywood?

I'm for the sand it first. Actually I like to use a wire brush with a handle on it to lightly scuff the surface, then run a palm sander with 180g to knock the loose stuff off and finish by wiping off the dust. I do however always use a good oil based primer as a base coat, I think it just makes the final product look better too.

I'll be doing a splatter paint job (to match the existing paint), which will result in a rough-textured finish. So, I won't need a primer coat for an ultra smooth finish. Based on responses it appears I won't need primer for top coat adhesion as long as I sand the resin surface.

 

[jbcurt00]

Re: Painting MDO Plywood?

I'll be doing a splatter paint job (to match the existing paint), which will result in a rough-textured finish. So, I won't need a primer coat for an ultra smooth finish. Based on responses it appears I won't need primer for top coat adhesion as long as I sand the resin surface.

W/ most paint systems it's advisable to prime before top coat. I'd probably use the recommended primer for whatever top coat you'll use.

Small effort to prime 1st. Large effort if there's a problem later. My 1 & 3/4 cents :watermelon:

 

[Woodonglass]

Re: Painting MDO Plywood?

I always recommend that you use the recommended primer. That's what primer is for!!!