Check out the original MDF vs. Plywood video: kzfaq.info/get/bejne/jN2oZrya28e0eJ8.html

My main observation with MDF is how it warps over time. It seems nice and strong at first but If I have a shelf made from MDF it will sag over time much worse than plywood with the same weight on it.

Fun bonus idea: measuring the difference in red water volume would help understand just how much is being absorbed by the pieces.

we used the physical properties of MDF to save our basement in case of flooding. Two tracks of U-shaped aluminium on both sides of a critical doorway, just slightly wider than the thickness of the MDF-Board. A bead of silicone to seal the entrance. If water entered the basement the MDF expanded and closed the gap in the u profile stopping the water to intrude any further.

I watched this and the previous video at cheap desk with a painted MDF top. When it gets a tiny scratch, any amount of water (condensation on glasses, spilled drinks, or even from sweat in the summer) causes it to swell and create bumps. There's no fixing it. Stumpy Nubs had a tip to use CA glue to re-seal the mdf, so it won't get worse in those locations, but the desk has pock marks all over it now.

At our shop we sometimes use “marine grade MDF” that’s more stable in situations with water exposure; we use it mainly for doors, in rooms that get lots of humidity

I made shelves a long time ago with MDF and they warped so hard it was more a roller coaster than a shelf even though there was very little weight put on to them (the vertical boards held pretty well which is interesting). I also made another shelve around the same time I made the MDF ones but this one was made from plywood and it is still standing strong even after putting a huge old heavy tv on it for years.

15:39 lol how excited you got at the failure. Love it! Great tests Brad!

I still think you need to test the MDF deflection over time. I'm reasonably certain if you put the MDF shelf under a load of a full month, it will deflect a lot more than when you first applied the load.

Brad, I hate to break it to you, but those ARE NOT bags of concrete, but rather concrete mix. 😁 Unlike the plywoods, the types of binders used in MDF produce VOCs that significantly contribute to "sick home syndrome"... and I hate the weight of MDF... moving full sheets of 3/4" gets old really quickly.

I always appreciate your videos! If you would have flipped the plywood over so it bowed downward, it would have likely been weaker than placing it with the bow upwards. This is the same reason they design flatbed semi trailers to bow upwards when they're not loaded.

Great job! Would be Intersting to see a similar test with exterior sheathing options like OSB, OSB with a weather barrier, and a zip type board. Could even test tape applications on joints, etc.

Two thoughts: One, I've noticed that both MDF and particle board fail slowly when they have a constant load on them. Shelves that seem fine with a certain weight when built will gradually bow and eventually break over the course of years. I suspect it has to do with changing humidity, but that's just a guess. Second, what is the water resistance rating of the glue in that plywood? I think most ply now uses water-resistant glue, but I know that if you soaked a piece of older standard plywood overnight you would just have a stack of veneer flitches when it dried out. MDF has its uses, but I wouldn't use it for anything that is load-bearing or that has a high probability of getting wet. These tests pretty much reinforce my opinions formed over several decades of using the stuff.

Great video! As far as moisture resistance goes....30 years ago I had Formica counter tops made. The counter top guy told me to paint the underside of the back splash with oil base kilz or oil base primer before he installed it. He said this would keep the particle board from swelling up if the silicon caulk seal should fail. I also paint the underside of the front (especially near a sink). I have had great success with both applications. I would also paint the side of the particle board on the side of the cut out for a sink. I would paint any wood product for this kind of application. (I was a professional painter. I would understand if people are saying, they paint everything.)

My experience is the same as the outcome of this video except for the solid wood edge version. I haven't done that, but I will now. I'll be using mdf in different ways now. Thanks Brad!!

I have not even seen the video yet ...but 600 pounds of concrete and a flame thrower have got me riveted to the screen!

The plywood that my company gets, comes apart from humidity change. I think it's held together by hope.

Brad, this video was very useful and I thank you for all the time and effort you put into it! But seriously: this was fun, you had me laughing out loud, for real!

If the materials are in danger of getting wet, use marine ply or waterproof (outdoor) MDF.

Brad-always appreciate these kinds of educational videos; am wondering if you could do an educational video on LEDs 101? I know you’ve done a couple videos (which I’ve watched) on putting LEDs in your work but feeling like I can’t find a soup to nuts video from design to installation on LEDs in woodwork and think you’d be great at teaching something like that. Thanks for any consideration you give this idea.

Interesting and informative video. I work on cabinets (mostly refinishing existing cabinets) and I have the same experience with MDF shelves that I'm reading in the comments about warping over time. I've seen it on both ply and MDF but is certainly more pronounced in MDF. If we don't end up replacing the shelves for whatever reason, I just flip them over.

Brad, thank you very much for your time and effort xo

Brad, thank you very much for your time and effort.

The last plywood deflection test had physics on its side. I would have liked to seen it tested with the bow down as well.

I don't even work with wood at all and I still watched the whole video. Thanks for being both educating and entertaining!

It would be interesting to see how exterior grade and marine plywoods compare.

Interesting, Brad. The arch in the plywood actually strengthened it. That's why it had less deflection. Look at a large dam and they're arched against the water pressure. Also, you were having entirely too much fun with that torch. Bill

Very interesting test :) You should also try to see if those smaller boards that were completely submerged would snap under load too. It would require a different jig, but it'd be interesting for sure :)

Informative and fun! I just wish you'd done the plywood at the end as well to show the load-bearing difference between them.

I’m digging the Mr. Brad science dad with this testing 😂. Also cool slo-mo at the end where the concrete bags were levitating. Good fun!

Re. the water tests; it would be interesting to see the results using marine ply (as used in boat building) which is made with a glue with resistance to long term water exposure, even under pressure (as when it forms the hull of the boat).

Great video! One interesting thing to add to the water soak test - you could weigh the water cup before and after the test. There could be a difference between surface and internal soaking. Weighing the water would give you the amount of water being held in each wood/mdf sample.

You have to be really careful when applying heat to MDF. Formaldehyde is usually part of the manufacturing process.

great video! The biggest problem I have with MDF is that even though it seems like it can hold a lot of weight, it can't do it indefinitely. little by little it will sag more and eventually fail. At least thats my experience with it.

We call it Major Deficiency Fixer because MDF is so versatile, I even use drywall mud on it to blend it into walls

These look like a combo of fun, curiosity, and hard work to make. Thanks! For future one’s regarding water exposure: 1) Seeing Marine Plywood in comparison would be interesting to see if/when it’s worth using 2) What easy and fast to apply finishes (and how much) return adequate water protection. Eg how far Water based Poly or Lacquer go vs expoxy. Is soray can sufficient.

It wasn't until AFTER the MDF snapped that I thought "I wonder if he's wearing steelcaps".

I'd love to have seen the edged MDF tested until breaking. For a follow up consider mdf versus moisture resistant (mr) mdf AND acetylated mdf (e.g. Trycoya). The latter has the wood fibres chemically modified before bonding making them hydrophobic. It is claimed to be suitable for structural work outdoors. Very expensive but, if it's as good as claimed, you might get a free sample from the manufacturer. Would be really interesting to see if the considerable extra expense is worth considering for e.g. making perfectly smooth external doors and trim.

This was so entertaining to watch! Scratched that geek itch with your %Swole chart for sure. I’m even a non-builder-handyperson type and this was great to watch. Well done

I really appreciate you taking the time to make videos like this. Awesome job!

The only thing I see that could be questionable when you place the weight on the shelf. You've got it dispersed across the two sides more than in the middle. I would be curious if you stacked one row of concrete directly in the middle vertically how much it would hold that would be a better representation of the strength

The only thing I would say is that by widening your gap that the mdf had to span you built in a flaw to your test because no matter the material, the wider the gap with weight centered on it, the more deflection and lower load capacity it will have. Wish you’d kept the gap the same width as when you were testing to 600 lbs. at that width you might have actually gotten to 1000 lbs. Also, did you consider testing plywood with a hard wood edge banding? That’s the most common method is hobbyists use. Love your content and the conversation.

Oh my god, you are an answer to my prayers Sir. As an entry level cabinet installer, I will have more confidence facing and explaining to my customers. You answered a dozen important questions in this 10 minute video.....thanks once again.

❤ (the vid i didn't know i needed! also, love how you talk fast and there isn't dead space. quicker to get info while researching, etc. :D )

That new MDF snap-dance is gonna be a big hit at the club! :D What really got me was the sealed MDF still swelling like crazy. In the past I've used SMD Sunflash fiberglass resin to seal MDF, but after seeing this, I'm changing my materials list for a couple sheltered outdoor projects to avoid MDF entirely. Thank you!

Great tests, data, and presentation! Easy subscribe Would be interesting to see how different woods fare in more realistic conditions - say a room with high humidity over the course of a few months. The wicking action I think helps the plywood dry faster, but that wouldnt necessarily be so relevant if the air itself was moist. Would be a hard test to do though, something so subtle over a long time vs something more extreme over a short time. Maybe a decent humid air test setup could be constructed within a plastic box with a little fan inside and then stuck in the garage for a few months It's a relevant point that warped wood can be stronger than flat wood, if you utilize the curvature to help distribute the force like you did in the shelf deformation test. Whereas I cant think of any situation where wettened mdf would ever get better The slowmo breaking looked like a cartoon with how much faster the wood floor broke out vs how long it took the concrete to start falling lol

Resided a house w/ an MDF like faux t1 11 of sorts. That Georgia Pacifc siding we replaced was falling apart lol. Over time plywood will (can) last a long time when used appropriately.

Kinda wish you'd have tested to failure on dry vs wet plywood & mdf, like that last test. Also it's probably worth mentioning in the swell tests, that that massive amount of swelling will do things like rip screws through MDF. Even if your shelf doesn't outright fail, it'll weaken and loosen considerably after even limited moisture exposure - not because the board itself is substantially compromised, but because the swelling and shrinking process is so extreme that it shakes the whole structure up.

Plywood comes in interior, exterior, marine, and treated. MDF comes in many different types also. You should also show OSB and particle board.

Another great video. In the UK we have different grades of MDF big box is worst ( crumbly edge ) , normal MDF and MR MDF ( moisture resistance ). Edit after a little research Medite ( better quality MDF maker ) also do a Flame retardant MDF , no added formaldehyde MDF , Exterior MDF , Breathable MDF , Lightweight MR MDF , Industrial (High density) MDF .

Thanks for running the tests! I was surprised at the performance of the MDF.

In regards to the wet shelf test when you were wondering why someone might have water on them long term - if someone raises houseplants or has a seedling nursery then you can't avoid a near permanent water presence on the wood. My grandmother did both the plywood shelves all had water stains.

Really interesting on the MDF with hardwood face, might actually consider that for shelving when I wouldn't have before.

Fantastic testing, Brad! Really well done! 😃 My problem with MDF is that it's REALLY humid here where I live... So, if I buy MDF and there are scraps left... They turn into mud in about 6 months. 😬 BUT... There's the waterproof MDF (which I forgot the name)... And I still need to try it! Anyway, stay safe there with your family! 🖖😊

The thing that's hardest to test, but that I've observed in the real world is how in humid environments over time the ambient moisture tends to soak into MDF and make it sponge up, and weaken then fall apart. Which is why when I was looking at vanities for my bathroom remodel, I looked specifically for wood construction and immediately nixed any that had any mention of MDF

Excellent testing Brad & that slow-mo at the end of the video is classic! 😂😂👍👍

weight distribution. place the weight in the center. you have it spread across the entire width of the board, which test the cleat strength, not the boards. Your results would appear faster that way.

wow look at all those plans you have. and reasonable! i'm coming back to get some as soon as i have stuff sorted that i have room to build!

Built a platform to hold my front load washer and dryer. Used 1 inch MDF for the deck. That was 8 years ago. Recently had to remove the washer and dryer, absolutely no issues with the MDF.

I'll buy the concrete from you since you didn't use it... You just have to pay shipping thanks 👍

I use a ton of mdf, but I only use Finsa fibrapan hidrofugo mdf which is moisture resistant. I left a piece submerged in water for about 24 hours and it was exactly the same size and shape. Would be really interesting to se you test different types of mr mdf and maybe marine ply 😊

Built custom cabinetry, shelving and whatnot for 30+ years and have never heard any tradesman call it "edge banding". 'Finished edge', 'nosing', 'front edge', 'trim boards', 'front supports'... probably a bunch more names for it. We always use 'edge banding' if it's just a veneer over the edge of the shelf material.

Try Medex mdf amazing product, use it for outdoor signs, have one that is close to 30 years old, still good shape, stiffer product too. Testing water resistance of an interior mdf really isn’t fair.

Interesting information. Thanks for spending the time doing it. But after building cabinets for 50 years. There is no comparison in the quality and strength of the cabinet between MDF and plywood. The plywood is going to be much lighter and much stronger because all of the joints are far stronger with plywood.

I hear what you are saying... If you want a thicker face profile on your shelving, get some 3/4" MDF and soak it in water. Boom! Much less expensive thicker shelf.

I think the big takeaway is that each type has its own uses. Some shared, some not. It's another tool that needs to be selected by use case.

One of the tests we used to do, when testing for the effects of moisture on a building material, is to run wet/dry cycles. More than long-term exposure to moisture, I think you'll find that the number of wet/dry cycles a material can withstand will surprise you, especially with mdf vs a wooden laminate like plywood.

This was amazing. I never know why I watch your videos since I do make anything but for some reason they are fascinating. You are such a nerd about exactness…that’s not an insult😂

Brad, thank you very much for your time and effort

During Christmas week of 1984, my wife, 9 yr old son and I went to my mother's house 100 miles south for a week. Temps dropped to about 22 degrees Fahrenheit, enough to freeze the water pipes in my mobile home. It was a 1969 model, built with 3/4" MDF flooring. The water covered the kitchen, living room, and hallway floors, all carpeted. We tore up the carpets and replaced them, and over the next 6 months, the floors started sagging between joists. I had to pull up the new carpeting, and replace the flooring. I used 3/4" CDX plywood (I think about $8.00/sheet at the time) and it's still there, having had pet water spills and another 2-day flood sit on it. I'd probably have had to replace MDF at least twice more.

Haven't watch the video yet but taking from the last one one of the issues with MDF is long term load, so it bents permanently over time.

5:35 I hope you used metric units for these tests. It's pretty each to see how much more accurate the millimeter scale would be in this test alone. Plus metric is much better overall for all use cases, except for some historical context.

Brad, I would have liked to have seen one more shelf tested - the radiata plywood with a hardwood face... I suspect that would be quite a bit stronger than the MDF/hardwood shelf.

When it comes to shelfs I have found it's about what happens after 5 years. And often the shelfs that didn't warp at all and weren't seriously loaded end up sagging tremendously. Take the shelf off and it is a permanent bend.

:)

After MDF has been wet, it's no longer structurally sound, but I still use it for forms, templates, and router carving projects. I glue a few layers together and use the router to make dishes and trays, then cover with epoxy or polyurethane and paint. If it's so far gone that it's flaky and brittle, it makes some pretty hot fires, once it completely dries again.

Dude is killing it. Great tests and presentation. Fellow Tennessean to boot! Go Vols!

Brad, than you very much for your time and effort. This was great.

THANK YOU!! My girlfriend has always thought I was using the word 'Deflected' wrong when doing DIY stuff around the house.... YOU sir have proven her wrong.. 😎😁

Well done mate But just saying, it would be easier to weight whe wood before and after soaking them in water, to see how much they have gained

Mdf is bonded with a wax and resin binder with high temperature and pressure, which is most likely why the surface resists water, but the cut edges allow more water in. As with any wood end grains not sealed, allow water to soak in due to the structure of the wood being straw like fibers

Another thing worth noting... marine grade mdf exists. In my humid environment of SW Florida, regular mdf is nearly worthless (unless you have $50k worth of plastidip lol).

Good video as always. I enjoyed the various tests you performed and have no complaints. I do wonder how well a “MR/moisture resistant” mdf such as Medite MR or a pressure treated plywood would have faired. I know we don’t usually use pressure treated plywood much as woodworkers but I do use MR style mdf on occasion. I am a fan but I’m not THAT heavy! 😊 Ron

You should've thrown a sheet of MDO into the mix. Since it's got an mdf overlay. From my understanding mdo is pretty much waterproof. It's an exterior glue used instead of interior, which I know will play a major role in these style of tests

Good content on these two videos. I'm curious what the absorbion weight is on the various materials. Also what the duration of time is to get each material back to near-new moisture content. Could also use a wood moisture meter to measure. Just some thoughts.

Great job Brad! Thanks for sharing the video with us!💖👍😎JP

Watched the last video and this one and found them both pretty interesting but I had a couple of random thoughts/notes I wanted to share. The line for the radiata pine on the chart at about 6:52 I think suggests some kind of non-elastic deformation above 400lbs. Maybe that was the eye-bolts getting bent/pulled out? or maybe one of the layers developed a crack? There's also just not that many data points so it could be just one of the measurements being flawed in some way. The bow going up making the board stronger makes sense geometrically: that's the design of the hoover dam. Something that might be interesting w/ the boards left standing in the water is weighing them to see just how much water they've absorbed giving us some more things we could graph (though I'm not sure just how actually useful those points would be for comparison purposes they might be fun to see). The way the three materials fail will likely be different and somewhat interesting. In the case of the mdf it's probably relatively tame when it fails and will likely break horizontally with relatively straight edges whereas I think the plywoods due to the grain structures will be a bit more spectacular w/ more jagged edges to the breaks and will probably be a bit more likely to fling chunks out. That's my guess anyway so it'd be cool to see it put to the test. Also, if you're gonna be intentionally breaking these boards you might want to consider some safety squints.

The quality of plywood varies greatly. I’ve had builders supply it and pick it up from a box store and it was made in Indonesia. It had a lot of voids in it and just all already was a cheaply made product compared to materials sourced from my local supplier that was made in the USA

I had a couple two gallon jugs of water on an MDF shelf. One of the jugs leaked and soaked into the MDF. The shelf dried but it has a permanent bow in it now. I just flipped it upside down to help counteract the bow.

I laughed way too hard at "Thank you very much for your time and effort" 🤣

So the take away here is, don't let wood get wet. Awesome, thank you.

When i made cabinet doors out of mdf i coated the edges in glue amd let it dry before painting them. Seals them really well.

So for the plywood loaded test, when you put the shelf in with the bow "up" it acts as a pre-stressed shape and resists deflection. If you had installed it the opposite way (bow down), it would have deflected more.

There's a water resistant MDF called Armorite. I've never used it before and would be interested in seeing it tested.

The upwards bow of the ply probably functioned akin to prestressing, reducing the deflection by adding forces acting against the added weight.

Thanks for testing the plastic shelf supports - I've always been leery of the ones supporting my 1x6 pantry shelves with, like, 5 lbs on them. Now I know I can jump up and down on them ;-) Not quite.

Hi I like your videos, I do a lot of door jambs, I made them from solid wood but I need to do better price and time. Am thinking mdf. What do you think ?

that slow mo at the end there was actually awesome and felt like a will e and road runner moment lol.

Would be interesting to add particle board to your tests. When I used to design and build melamine furniture, we almost always used MDF for verticals and particle for horizontals - especially where we needed less flex, like shelving.

Plywood was placed bow-up. The bow, acting as an arch, is the source of the increased strength. Had you placed it bow-down, it would have deflected more. Thanks for the video. Was a lot of fun. First time I've seen your channel.