LumberJocks Woodworking Forum banner
Cancel
Create thread New Forums

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

1 reading
Jump to Latest
104K views 40 replies 33 participants last post by  pianomoverslancaster  
#1 · (Edited by Moderator)
Medium Density Overlay - Plywood for Jig Building and General Use (Rating: 5)

As an alternative to the less than ideal MDF, a cabinetmaker friend of mine recently turned me onto "MDO", aka "Signboard". It is made up of phenolic resin coated paper laminated between layers of ply (11 layers of wood in 3/4") and twice again as many of the phenolic- resin impregnated paper. Its what roadsigns are made of, its waterproof, flat , flat, flat and did I mention waterproof?

You wont find it in Home Depot or Lowes, I have looked. I have had success at many of the local lumberyards catering to contractors and other construction "Professionals:. The nice thing about this material for jig building is that it is relatively void free like marine ply and the paper exterior is very smooth. It is not quite as hard or slippery as phenolic ply but I think availability and price is much better than the hard to find fully phenolic plywood. My local lumber yard carry's it in 3/8'ths, 1/2" and 3/4". A 4/8 sheet of 3/4" MDO up here is $65.00.

I really like MDO for projects that call for plywood of any kind and have been using it exclusively when I can. As a side note, I hate MDF and have never been impressed with it for anything other than creating a noxious dust storm and blown out screw holes. I never understood it popularity but there are those who argue that its great…

Here is a link to the exact product I have been buying; Follow blue hi-lighted text for mfgr's website.

The MDO I have been using lately is so pleasant to work with, cuts and machines wonderfully, accepts primer and paint like a magnet and has the added bonus of being moisture resistant even after being cut. Its about half the price of marine plywood. I have actually been thinking about building a 20' Dory out of the stuff.

If you haven't tried it for anything yet give it a shot. I bet you will be as impressed with its qualities as I am.

Image


Here are some notes from the MDO/"Lusterboard" manufacturers website

MDO Plywood - The Paintable General Purpose Panel

Characteristics: An EXTERIOR type plywood with a weather-resistant resin overlay bonded to the wood by heat and pressure. This process fuses the molecules of the overlay with the fibres of the wood to form a bond as strong as the wood itself. MDO has all the advantages of regular plywood as well as additional properties. The overlay, which has 28% resin content, resists water, weather, wear and degradation. It has texture that paint can grip with remarkable tenacity. 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.

MDO

MDO is saturated with Phenolic Resins, just not as much in the paper layer as the true phenolic ply.
"
MDO (Medium Density Overlay)

MDO is made with a high-quality paper saturated with phenolic resin solids and overlaid on exterior-grade plywood panels.

The selected hardwood veneer beneath the overlay is free of patches, providing a smooth surface with minimal grain show through.

MDO plywood is manufactured with waterproof resins that meet or exceed all veneer-grade, adhesion, and construction requirements.

It is stronger, more rigid, and less subject to creep than composition products. Innerplies and backs are all ÒCÓ grade or better.

MDO plywood can be sawn, nailed, routed, shaped and drilled.

The overlay is bonded to a hardwood substrate for a smooth, paintable surface and may be specified on one or two sides. "

I am so glad I found this product, it really gives jigs, cabinets and other projects that you will otherwise paint an easy to work with, fairly economical, durable and weatherproof material option that I did not have on my radar before now. Try it, I am betting you have a use for it and did not even know it!

Enjoy
 

Attachments

Save
Reply Quote Like Like
#9 · (Edited by Moderator)
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.
 
Save
Reply Quote Like Like
#10 · (Edited by Moderator)
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.
 
#11 · (Edited by Moderator)
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.
 
#14 · (Edited by Moderator)
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
 
Save
Reply Quote Like Like
#16 · (Edited by Moderator)
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 .
 
#18 · (Edited by Moderator)
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.
 
#20 · (Edited by Moderator)
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.
 
#26 · (Edited by Moderator)
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
 
Save
Reply Quote Like Like
LumberJocks Woodworking Forum
posts
2.5M
members
128K
Since
2006
A forum community dedicated to professional woodworkers and enthusiasts. Come join the discussion about shop safety, wood, carpentry, lumber, finishing, tools, machinery, woodworking related topics, styles, scales, reviews, accessories, classifieds, and more!
Full Forum Listing
Explore Our Forums
Blogs Power Tools, Hardware and Accessories Woodworking Skill Share Off Topic Coffee Lounge Hand Tools