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



## JohnGray

FYI - Our local Menard's carries MDO.


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## LoggerHead

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


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## mauiwindwalker

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


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## AaronK

no noxious dust?


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## blackcherry

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


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## Routerisstillmyname

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


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## bobthebuilder647

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


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## araldite

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.


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## WindwoodTrader

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.


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## SteveMI

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.


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## a1Jim

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


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## MattinCincy

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


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## Tractorshaft

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


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## FunnelStudio

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.


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## Dusty56

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 .


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## Dusty56

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


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## WindwoodTrader

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.


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## JJohnston

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.


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## jake

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.


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## boboswin

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


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## stefang

Send some MDO to Norway!!!


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## boboswin

They probably have it there too Stefang.

Bob


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## gwurst

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.


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## shopmania

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


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## Tractorshaft

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


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## Russ_Loves_Tools

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.


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## JoeLyddon

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…


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## toymike

Sounds better than MDF to me, but would it make a good bench top ?


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## SuperCubber

Sounds awesome. Has anyone had any luck using this as a benchtop?


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## DS

You can buy the resin impregnated paper as a veneer sheet. 
Around here it is called Polybak. I use it as a backer sheet to balance my veneer layup panels. It also does wonders as a backer on PB for durable laminate tops.

Adding Polybak to laminate tops also increases the strength of the panel and it can bridge slightly larger spans for work spaces, etc.
It is really clean stuff and adheres very well.

MDO is a great product and very stable. Ditto all the positives above.


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## WindwoodTrader

Supercubber-
You should read several of the prior posts (including mine) that state MDO make a very good benchtop. Mine has been in place for 10 years. 
Whenever I seriously damage the top I just carefully cut out the damage and using a pattern router bit replace with a duplicate "plug".
Works great.


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## SLCcarpets

So many great ways to use it. Thanks


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## Gene01

> 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.
> 
> - JJohnston


Same with Arizona. I've been searching online for MDO and, can't find it anywhere in the state. Unfortunately, Menards isn't out this way.

Edit…finally found it in Phoenix. 160 miles away.


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## ianmugoya18

acr could you please clarify on what you mean… i am abit lost. Cause on my end i have used the MDO for my roofing company and the results have been not good. Give me some hints on this on my email. [email protected]


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## ianmugoya18

it is worth noting that MDF is not nearly as stable as plywood, it will expand and contract with … are making a shaper of router table jig, your edges won't be smooth. .... I make jigs for "lawn art", and short term use out of MDF which result in excellent result based on results form. At first glance, all of the large panels in the plywood aisle may look the same. but they arent.


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## tom4tide

Like somebody previously stated, Norm Abrams used MDO a lot for many projects. It is very stable and waterproof. Many of his work station projects were made from MDO and even a custom mailbox. Weight is comparable to ply…much lighter than particle board. Cost & availability are negatives but it's good material for outdoor projects and is user friendly. Great work surface for benches. Believe that 3/4", 4×8 is about $65. Big box retailers don't stock it or Melamine sheets either. Smaller lumber yards often keep it.


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## tom4tide

Like somebody previously stated, Norm Abrams used MDO a lot for many projects. It is very stable and waterproof. Many of his work station projects were made from MDO and even a custom mailbox. Weight is comparable to ply…much lighter than particle board. Cost & availability are negatives but it's good material for outdoor projects and is user friendly. Great work surface for benches. Believe that 3/4", 4×8 is about $65. Big box retailers don't stock it or Melamine sheets either. Smaller lumber yards often keep it.


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## secharles

little or no waste is a plus, too.


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## blareblare

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.


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## pianomoverslancaster

Thanks for sharing this amazing tips!
Lancaster Piano Movers


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