Medium Density Overlay (MDO) Plywood for Jig Building and General Use

FYI – Our local Menard’s carries MDO.

-- Only the Shadow knows....................

Been using it for years – love the stuff .. also pick it up at my local Menards

-- Dan M, SW Suburbs, Chicago IL -- http://www.djay-crafts.com

Thanks for the review. I’ll give it a try. Been wondering about it and this will help motivate me!

-- Jim, www.greenteawoodworking.com

no noxious dust?

Great review and fine Jerry, I’m sure this is going to go over big….Blkcherry

I’m sold. Join the I hate MDF club.
Any links?

-- Router è ancora il mio nome.

This stuff sounds good.
I have never used MDF.
I use a lot of partical board, but it certenly is not moisture proof.

-- Rick, Pa. Courage is what it takes to stand up and speak; courage is also what it takes to sit down and listen.

Good tip. I’ve never heard of MDO. I hate MDF. I actually roll my tools out of my garage and do all my cutting outside on my driveway because the dust drives me nuts and it takes days to filter it out of my shop. I think I must be allergic to MDF. I’m going to look for MDO in my area.

-- Vince in Greenville, SC

I found out about MDO on the Norm Abrams New Yankee Workshop about 15 years ago and have used it for several jig projects. One major use that I found really worthwhile is to re-surface the WORKMATE top that is nothing but particleboard that swells when it gets wet. MDO won’t swell.

Another great use is to re-surface the radial arm table. You can customize radial arms to your need- Same as with the Workmate stuff. One more is to build a poor man’s version of the great FESTOOL project table.

MDO is available in 1” but really expensive. If I need more than 3/4” I will sandwich 3/4” or 1/2” onto a 5/8 exterior grade A/B or A/C and if appearance is important veneer the edges with laminate- Works great! If you have money just sandwich two MDO panels together.

-- John

I found out about MDO couple months ago. My info was that it originated from the needs of concrete forms where it had to be water resistant and resusable from job to job.

I bought a 1/2” full sheet for $30 locally and have been using it with great success. Cuts great, real flat, glues well and paints well.

Planning to use it for some shop cabinets.

Wonder why it isn’t used more for the panels of kitchen cabinets that are hidden?

Steve.

I’ve used it for years I agree it’s a great product

-- Jim from Heirloom Woodshop Southern Oregon

There’s a Menards about 45 minutes from me so I’ll be heading there this weekend to get a sheet – can’t wait to try it on a few table saw jigs I need to make.

Matt

-- Wag more, bark less.

Hi Guys,

Great, I am glad to hear few negatives about the product. I tested some glue joints (lap) and dado to destruction yesterday and was pleasantly surprised to see that the “Paper” layer did not delaminate from the “Skin” of the ply. The “Paper” layers appear to be almost melted into the wood under great pressure and heat. Basically when you glue it, its stuck for the long haul!

Jerry

-- Jerry, "Some people are like Slinkies, They aren't good for much of anything, but they put a grin on your face when you push them down a flight of stairs"

This stuff is really rad. You can also get it pre-primed, which results in a super smooth surface depending on how it’s been handled.

Excerpts from MDO manufacturer …”The surface is laminated with a resin impregnated fiber. The resin creates a very weather resistant barrier that when primed and painted, provides one of the best water and UV resistant surfaces. We emphasize that it still must be primed and painted according to industry standards. Never allow it to get wet before being painted. ”

Edge Sealing

The most vulnerable portions of overlaid plywood are the edges. Because they absorb water which can lead to finish and surface deterioration, the edges require the most effective protection. Two coats of edge sealer must be applied for adequate protection against moisture penetration.

Although I agree that MDO is a great product , in over 20 years of handling it , I have never seen paper layered between the core plys as you indicate in your post above. The fiber resin is in the “overlay” which is the paper on the outside of the plywood , hence the name Medium Density Overlay....I don’t know who your supplier is , but the 11plys is outstanding to me as most of mine has been 7-9 ply 3/4” , here in the NorthEast.
I realize that there are several manufacturers out there with their own recipes that meet the APA codes . I just want others to know that they might not end up with the 11 ply brand when they go shopping for jig material, etc.. : ) Thank you .

-- You know you're getting old when you know the difference between you're (you are) and your (belonging to you) AND how to use them in a sentence .

They also had this WARNING posted
MDO DUST IS TOXIC ! CARE SHOULD BE TAKEN TO AVOID INHALING IT. BREATHING PROTECTION IS A MUST WHEN WORKING WITH THIS MATERIAL. EFFECTS OF INHALATION ARE EXTREMELY HARMFUL TO YOUR HEALTH
ditto for MDF

-- You know you're getting old when you know the difference between you're (you are) and your (belonging to you) AND how to use them in a sentence .

The primary use for MDO is for traffic signs like along the major highways. They are exposed to all sorts of temperature change and weather extremes and keep on ticking. It is great for garden potting tables, building covered trailers, planters, deck sheds and storage boxes, outdoor shelving, stair treads (grit painted of course) and really good as a workbench top.

I believe the panels with the 11 plys are sign specs by the various governments that erect such.

As far as toxicity is concerned the EPA came out about 10 years ago stating that ALL glued panel stock is considered toxic.

-- John

I sure would like to know where to get this stuff. THE worst thing about living in New Mexico is that so many products and services are just not available here.

-- Measure twice, then try to figure out which one was right.

There are many manufacturers of MDO products so the quality varies. Many products are coming out of China, with some being very good and others less desireable. Some look like MDO on both sides but are not, as the ply can be made with one side being MDO and the other a brown film paper top. There are generally 3 levels of quality, resin paper coated plywood, MDO and HDO. The first is a decent product but is less robust than MDO and MDO is less robust than HDO. MDO is ready for paint and is why it is often used for signs while HDO has to be scuffed for paint adhesion but great for really heavy duty tasks that need chemical resistance and great durability. Any structural joint using these products should be mechanical and really not try to bond the paper film top to something with an adhesive. The bond should actually be with the wood substrate if that is what someone is trying to achieve and the film top removed in some manner, like a shallow groove, dado, etc. otherwise the joint is likely to eventually fail under load. Not that you can’t glue it, as I have but in time the professionals say the bond may fail. I have used epoxy with some success but after learning this I have changed my approach when using it for furniture frames. This information is from the plywood manufacturers association, who know the products qualities and best uses. Any cut to the panels requires the edges to be sealed in some fashion, and most suggest a waterbased, exterior finish of some type. I have used MDO extensively and come to like it. It is somewhat like working with Melamine, as you need a higher count tip/sharp blade to cut it smoothly to avoid chipping at the edge of the cut. So that is why be aware of the deals out there, as there can be a fair amount of variability in the product. I love the stuff, just wanted to pass along what I have learned.

I thnk you may find “off cuts” at a sign shop that you could probably get at a discount.
We used to end up with several kicking around that were too good to throw out and not good enough to keep.

Cash is King and whiskey is a great negotiator. <g>

Bob

-- A mind, like a home, is furnished by its owner

Send some MDO to Norway!!!

-- Mike, American in Norway

They probably have it there too Stefang.

Bob

-- A mind, like a home, is furnished by its owner

The Menard’s stuff I bought made decent jigs, but I highly doubt it was waterproof. There also seemed to be a lot of voids in the plays. Undoubtably cheaper stuff than the signboard you used.

-- You're a unique and special person, just like everyone else.

Thanks for the info, I’ll check it out.

-- Tim, Myrtle Beach, DrTim@ONeillChiro.com- Guys DO like shopping, as long as it's for tools! :)

Greg speaks of the cheaper variety of MDO, I too have “Found” some of this stuff and realized the minimal cost savings was false economy. I did however warm up some west systems two-part epoxy and put it in a big syringe and pumped the “Voids” that were visible full of the stuff. It works wonders and really serves to strengthen an otherwise excellent piece of wood. Have a great day!

Jerry

-- Jerry, "Some people are like Slinkies, They aren't good for much of anything, but they put a grin on your face when you push them down a flight of stairs"

I would like to join the I hate MDF club however, at 1/3 the cost of MDO I’ll keep breaking my back lifting the 90+ pound sheets until I need something that’s waterproof. If I want quality plywood jigs I’ll use 5’x5’ sheets of Russian/Baltic Birch.

-- Russ

Isn’t there a “Lite” – “Light” MDF?

Any good? Any reports?

MDO sounds good, in it’s field… MDO is not in MDF’s field, IMHO…
... different animals…

-- Have Fun! Joe Lyddon - Alta Loma, CA USA - Home: http://www.WoodworkStuff.net ... My Small Gallery: http://www.ncwoodworker.net/pp/showgallery.php?ppuser=1389&cat=500"