MDO as a workbench top? What glue?

[Mark Burnette]

I'm building a reloading bench and I thought MDO might make a good work surface without needing extra steps to paint or poly for protection. Time will tell how rugged it is--but reloading shouldn't subject it to much abuse.
Choosing it has created an unexpected issue for me, though. My bench top is 2 layers of 3/4 ply and to bond the MDO top sheet to the regular ply bottom sheet I realized I can't use regular yellow glue. To get a good intimate bond I also can't use construction adhesive or a thick glue.
I think that only leaves me with epoxy.
Is there something else that might be a better choice to bond with MDO? It's my first time using it.

[Paul F Franklin]

My ww bench is 4 layers of MDO with solid oak edging. I used polyurethane glue for the MDO sandwich and it worked well. Also has the advantage of longer working time. I spread the glue on one surface with a roller, and spritzed the other surface with a spray bottle. I did two groups of two and then glued those together but I think I could have done all four in one step. I used lots of clamps and cauls to keep the surface flat.

After a few days, I took an offcut (I made the benchtop oversize and trimmed it after gluing) and tried to separate it at a glueline with a chisel. The wood failed in spots, the overlay to wood bond failed in spots, but as far as I could tell, the overlay to overlay bond didn't fail anywhere.

The top has held up well so far, although it doesn't see really heavy action in my shop.

[Jerry Bruette]

Why not put a few screws in to hold the top down?

[John TenEyck]

Actually, you can use yellow glue with MDO. Just rough up the surface a little with 100 grit and it glues fine.

John

[Jim Becker]

Personally, I feel MDO would be a poor choice for a workbench top but it would be fine for the second layer. I'd stick with MDF for the actual top if you want to use a composite. MDO's top layer is a very thin paper or MDF veneer and is easily damaged. Some MDO also telegraphs the grain of the exterior plywood core.

But to your glue question, you absolutely can use normal PVA glue with MDO...it's paper/MDF/Plywood.

[Erik Loza]

I would likewise think about MDF over MDO. The plastics company I did a brief stint with sold MDO, since a segment of their business was sign shops. The basic premise of MDO (at least for us) was "it's a cheap wood panel that lasts longer than expensive wood panels" outdoors but beyond that, no real redeeming characteristics. Just my experience. Good luck with your project.

Erik

[Mark Burnette]

Am I wrong about MDO? I've read the top layer is resin-impregnated paper that's weather-resistant.
I took that to mean it wouldn't be affected if I got some water or solvent on it, unlike MDF that soaks it up and swells.

[Jim Becker]

Am I wrong about MDO? I've read the top layer is resin-impregnated paper that's weather-resistant.
I took that to mean it wouldn't be affected if I got some water or solvent on it, unlike MDF that soaks it up and swells.
Yes, it it is weather resistant, but ONLY after it's painted. The paper is very thin and the main reason for that is to provide a very smooth surface...for painting. I have another full sheet in my shop from couple of projects "as we speak? My opinion is that the surface is not "physically durable" as you would want for a work surface.

[Mel Fulks]

The mfg. of the stuff really pushes that it must be painted. If you will be sliding stuff around on it. You need to paint it
or cover it . Even old newspapers would help.

[Brice Rogers]

I have several workbenches. They have 1-1/2" thick plywood tops attached to formed HD steel legs (industrial shop benches). Two have masonite tops and two have formica tops. Both have turned out to be fine after 20 years of use. The one that gets the roughest treatment is one of the masonite tops that I painted initially and which I re-paint every 3-5 years with some light colored gloss or semi-gloss discount/mismatch paint from HD.

I too would find MDF and MDO too soft of a top surface. Just slightly better than raw plywood. If you are going to drill holes in wood and perhaps drilling into the top surface of the MDF/MDO, then it doesn't matter what you do. But if you want a top surface that isn't going to see that sort of rough treatment and you want it to look nice for as long as possible, consider Masonite or a Formica type product.

[Jim Becker]

Brice brings up a good thing that could be relevant if you already bought the MDO...make your work surface with a couple layers of the MDO, put a solid wood edge on it that's proud of the surface by the thickness of a piece of "Masonite" (hardboard) and make a replaceable insert out of said hardboard. Lots and lots of folks have done this over the years. If you get the hardboard in "slick both sides" you can have a pristine surface for assembly and a "not pristine" (used) surface for things like finishing and just flip. When things get too worn, make a new topper.

[Alex Zeller]

If you haven't bought it yet I would suggest HDO over MDO. It's used as forms for cement work. I believe you can get it in a one sided version. As for gluing it I would use construction a adhesive like PL400. It's cheap and will work well. It comes in a caulking tube and can be troweled into an even coat.

[Scott Winners]

My reloading bench top is some kind of particle board, 3/4" single layer, much smoother than any plywood, handy for keeping brass standing up straight. The only alterations I did were to sandwich the particle board with a half inch layer of red oak top and bottom at the places I bolted stuff down like my press and trimmer.

Where I bolted the board down to the metal frame of the bench undercarriage I just used a regular washer and then a fender washer on the bolt head showing proud on the bench top, and then whatever fit under the nut on the underside. The washers and bolt heads are not countersunk, I was concerned the remaining top material would be too weak if I countersunk.

I used 3/8 hardware on my rockchucker, 1/4 inch for the trimmer and autoprimer. If I was going to mount a progresive press I would grab a couple glued up panels from the home center, something like 12x16x1 nominal, mount one of those top and bottom and then drill all three layers to mount the progressive press with 3/8 hardware.

[Mark Burnette]

I was going to post a water resistance test I did but then found I couldn't include pictures. I'm very sorry to see this forum go that way.

[Mel Fulks]

All of the one good side MDO type stuff I've seen wouldn't stay flat without screws.

[Jim Becker]

I was going to post a water resistance test I did but then found I couldn't include pictures. I'm very sorry to see this forum go that way.
It's only six dollars to be a Contributor and have access to Photos, Classifieds and Private Messaging. This change was made sometime ago and isn't something new. It costs a lot of money to run a huge forum like this and nobody's making a profit. Advertising doesn't cover it, either, especially with a huge percentage of folks blocking them. I hope you'll consider making that tiny contribution to both help keep the SMC community strong and also have access to those features.

Jim
Forum Moderator