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Can one laminate an MDF panel to plywood and still maintain dimensional stability?

I'm building a 4' x 2.5' desk primarily out of maple (I intend to use either cherry or walnut for trim) and for the top I'd like something thick and heavy. Veneer core plywood is an obvious candidate for the top but it will be neither thick nor heavy enough. My idea was to laminate the plywood to some MDF and then use hardwood for edge trim. My concern with this is that despite the stability of both the MDF and plywood, laminating them together will cause problems with warping.

An alternative would be to build a frame similar to that of a floating shelf and then attach the maple plywood to the top of the frame. I have no objections to this but it's significantly more work.

  • Another alternative (not that you need it) is to laminate 2 pieces of plywood together, and forgo the MDF entirely. You should be able to get 3 suitably-sized pieces from one sheet of plywood, so you may save yourself some money this way (barring you using the remaining plywood for anything else of course). – mmathis Sep 3 '18 at 22:52
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Can one laminate an MDF panel to plywood and still maintain dimensional stability?

I'm not sure why would you might have thought that combining two dimensionally stable products would somehow introduce an instability. If you think about plywood itself, this is layers of wood veneers that aren't dimensionally stable but when glued together you get something that is dimensionally stable*.

Veneer core plywood is an obvious candidate for the top but it will be neither thick nor heavy enough. My idea was to laminate the plywood to some MDF and then use hardwood for edge trim.

That's perfectly feasible and how many working surfaces are made up these days. My workbenches are all essentially made in this way, the ply hiding underneath MDF in my case, with wood strips all around to provide a durable edge.

You do have to be careful how you go about glueing the ply to the MDF in a lamination like this if you want a good bond, it's not quite as simple as it seems. If you'll be using PVA (white or yellow), or foaming polyurethane adhesive, you want to make sure there's quite a lot of pressure holding the layers together which can be difficult to arrange without recourse to temporarily tacking or screwing the boards together, something you may not be able to do here (depending on the thickness of the veneered ply).

So if you can't tack the boards together while the glue dries be sure to use enough clamps or very heavy weights to ensure you're firmly pressing the centre of the panel together (clamping the periphery is not sufficient on larger panels). See more in Gluing plywood together. Do also take note of the tip in the last paragraph.


*Not entirely, but so much so that its movement can usually be ignored.

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    The issue is that while both MDF and plywood are stable sheet goods, their characteristics differ enough that I could have an issue. I didn't think there would be a problem but since I've never done it I'd rather someone with experience share their experience so I don't waste several hours and $200. – gvkv Sep 3 '18 at 16:17
  • Brass and steel both seem "dimensionally stable" at room temperatures, but the small difference in their rates of thermal expansion still cause a bimetal strip to move a lot even with small temperature changes. Don't be so quick to dismiss the OP's concern. – Caleb Sep 3 '18 at 17:21
  • Context is everything @Caleb — material type, thermal/moisture, thickness. – Graphus Sep 4 '18 at 9:24
  • I'm just saying that the OP's question is entirely understandable and undeserving of your I'm not sure why would you might have thought... – Caleb Sep 4 '18 at 12:32
  • @Caleb, and I'll just say that that passing remark should not be read in isolation. Even putting aside a spurious comparison between metals and wood the comment is part of a paragraph where I expanded on the gist of what I was getting at (i.e. it wasn't just said in isolation where it could be read as a put-down). I added that specifically for this reason. – Graphus Sep 4 '18 at 13:12
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Are you going to be in an environment with large fluctuations of humidity and temperature, perhaps outside the range of comfortable human habitation?

This is just a gut feeling, based on secondary experiences over time, but the combination you're suggesting has quite a bit going for it. The plywood is, of course, a series of laminations of wood, with grain in various directions. Adding a piece of MDF to this merely provides another layer, grain-less that should not generate distortions in the overall piece. The glue used to bond the wood should be evenly distributed and clamped as per manufacturer's instructions. In so doing, you're providing for the uniform application of force over the entire piece.

If the assembly is going to have extremely high levels of humidity and temperature, followed by dryness and cooler temperatures, I doubt the plywood would hold up on its own, nor the MDF. Even joined, moisture would be your primary enemy.

Perhaps if this applies, a sealer on the completed project to keep moisture out, but I'm betting that moisture is not a factor in your application.

I believe you can accomplish your objective successfully.

  • Just indoors so humidity changes are limited to the Great Lakes region of Canada. – gvkv Sep 3 '18 at 23:11

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