Plywood core for Laminated Cherry Bathroom Cabinets

[Eric Arnsdorff]

495192


I will be vacuum laminating Cherry onto a plywood core to make panels on some upper (countertop) cabinets for my bathroom. I will be re-sawing Cherry lumber that I have to make the larger panels for the cabinets. I expect to make the pieces ~1/4" thick and put a 1/2" to 3/4" strip on the edges of the laminated plywood. So only the back edges would be exposed and those would be against the wall.

My question is if I should be concerned with using MDF for the plywood core?

I'm interested in thoughts on this in a potentially humid environment. One of my justifications is that the drywall in this portion of the bathroom is the standard drywall and there is no issue with it. So I don't think MDF would pose any problems in a bathroom environment for this application. I am interested in feedback on this.

Note - I will also be following this up with a tall floor standing cabinet as well and the same question I have applies.

[Maurice Mcmurry]

I have had problems creating laminations that are unbalanced. A knowledgeable lumber sales person that I questioned about why the cabinets I had made had warped told me that I had created un balanced panels by not having the same amount and type of material on both sides of the core.

[Jim Becker]

You "should" be fine with the ~1/4" material but "thinner thick veneer" would be better and reduce risk further. Along the lines of Maruice's comments, both sides of your substrate should be veneered with material of the same thickness and preferably the same species or compatible species relative to wood movement. Your edge banding doesn't matter much and leaving the wall facing edge bare shouldn't be an issue functionally, but putting solid stock on it would help seal it better.

MDF is fine for your substrate, IMHO, but exterior rated MDF is an even better choice. But ALL edges must absolutely be sealed for moisture resistance.

[Eric Arnsdorff]

Thanks for the feedback.
I do laminate both sides. I didn’t mean to imply it was to be on one side.

I’m open to use any other core material if there is a better choice. I don’t know of a source for outdoor MDF. I can check on that next week at the local supplier in town.

[John TenEyck]

The doors and drawer fronts on two cabinets in my bathroom have standard MDF cores with 3/4 wide edging all around and then veneered with 1/16" shop sawn veneer. One is close to 10 years old, the other around 5. No issues whatsoever.

I would not use 1/4" material. It's not veneer at that point, it's wood that wants to move. MDF is ultra stable. See the potential problem? I would not go thicker than 1/8".

John

[Eric Arnsdorff]

Thanks John! I think Jim was also indicating to resaw the cherry a bit thinner and is something I can do.
Knowing this has been proven to work is very helpful!

[Mel Fulks]

I think the old books call 1/8th and over a “facing “. Thinner is “veneer “

[Jim Becker]

Thanks John! I think Jim was also indicating to resaw the cherry a bit thinner and is something I can do.
Knowing this has been proven to work is very helpful!
1/8"-3/16" max would be my recommendation for the veneer...you may need access to a drum sander to get that smoothed without tearing it apart, but some portable planers can sometimes thickness down to that level without destroying the wood. I've successfully used 1/4" material for faux rails and stiles, but like John, I'd be really concerned about a whole panel "veneered" with that thickness.

[Jamie Buxton]

Thanks John! I think Jim was also indicating to resaw the cherry a bit thinner and is something I can do.
Knowing this has been proven to work is very helpful!

I do a lot of thick veneering, cutting the veneer on my bandsaw. I generally cut it a fat sixteenth -- .08"-.1". The saw leaves a gluable surface, so I sand it after gluing it to the substrate. Sanding leaves the veneer .06-.08" thick, which is way thicker than commercial veneered plywood. I veneer both faces of the substrate with the same veneer thickness.

I edgeband with solid lumber, around 1/8" thick. Usually I edgeband after veneering, but with veneer this thick, it is possible to edgeband before veneering. The veneer is thick enough that you can ease the corner without going through it. The thickness also means that the veneer doesn't fray in service, which conventional veneer would do.

For me, a big issue with an MDF core is that is doesn't hold screws well. In cabinets, that mostly leads to problems with door hinges. I have glued hardwood plugs into the substrate where I know screws will be, and that works, but it is easier to use plywood for the substrate.

[John TenEyck]

I have used wide inserts of solid wood for better screw holding in MDF. But I've made a lot with hinges directly in the MDF, and never had a problem with Euro style hinges. The cup does most of the work; the screws are there more to keep the cup from rotating or falling out. You can fill the holes with epoxy or even yellow glue when you drive the screws for added reinforcement, if desired.

The big issue with plywood is it's often not truly flat, even Baltic birch these days. I've never had that problem with MDF. No material is perfect.

John