Plywood is plywood, right?

By , 25 September, 2010, 1 Comment

Wood furniture and cabinetry is built of, you guessed it, wood.  And while all wood comes from the same basic source (trees), that is where the similarity ends.  Logs are milled into hardwood lumber boards, sliced into veneer, chewed up and pressed into engineered panels, and even cooked down into paper.  I don’t build furniture from paper, so we can drop that category right there.  Engineered panels offer some advantages, but I don’t use them much either, and that is an entirely different post.  Most of the projects that I design and build utilize hardwood lumber boards, or blanks, and hardwood plywood veneer panels.

Everyone understands what hardwood lumber boards are.  Hardwood plywood veneer panels, however, need a bit of explanation.  These panels consist of several inner layers of wood glued together at right angles and then faced front and back with a nice thin slice of the chosen species.  For example, a sheet of Walnut plywood has the same core as a sheet of Cherry plywood, which has the same core as Maple plywood, etc…  The only real difference is that the outer layer, the one that we see, is the preferred species.  Still with me?  The core plies in any hardwood plywood are the same basic material.  But there are some critical differences in plywood.

First of all, the glue used to bind these plies.  I specify Columbia Forest Products PureBond plywood for most of my projects.  Why?  Easy.  It’s made in the US and uses a formaldehyde-free glue.  So, no off-gassing of urea formaldehyde in the final product.  Better for me in the shop, better for you in your house.

The second major difference is tied closely to the first; quality.  Plywood that is manufactured in the US is held to a higher quality standard than those made overseas.  The wages for the employees are higher, the workplace is safer.  I like these things.  And I support those things in what little sphere of influence I  have.

Several years ago I was asked by a client to build a project for as cheaply as possible.  Their budget simply did not allow for a higher quality material and I was hungry for the work, so I agreed.  We used an imported plywood that was to be painted.  Several of the sheets deformed once they were cut.  Usually this happens because the lay-up from the factory is not balanced in layer thickness or moisture content, or both.  Since these deformed into roughly the shape of a rainbow, I would guess both.  When this happens it is always a quality issue.  But what really turned me off imported plywood was the one sheet that I cut into only to find that two of the inner plies had no glue between them at all and the panel immediately delaminated.  But even that was not the worst of it.  The worst part was that inside that delamination was what looked like blood and hair.  I swore off imported plywood that day and have not used it since.

I realize this may be more than you ever wanted to know about plywood, but if you’re considering having some cabinet or furniture work done, it may be of interest.  Different manufacturers will have different reasons for using the products they do and some of those reasons may be valid.  But make sure you know what you’re buying before you toss down a stack of cash.  A bit of time spent now in education could save you alot of heartache later when you find that what you paid for and what you have are not the same thing at all.


1 Response {+}
  • Robo

    Oct01 Your chair is easily one of the most elaegnt forms in plwood I can remember seeing. It’s beautiful in plywood like none other. It really transcends the material. I don’t know how you achieved the strength at the front left and right corners of the seat. It is more as even plywood than I think it would be in metal, though there are textured stainless steels that are pretty cool and might be enough texture on say just the seat panels to give the chair a moore slightly more substantive presence than I think a single surface, particularly smooth, would. Avery, very nice piece. almost / maybe timeless, which is hard to accomplish these days. Brave.

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