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Let me start with a confession. I began my woodworking
career with a prejudice against sheet materials of all kinds, and I still
carry puritanical tendencies that lead me towards real wood whenever I
can get away with it. That said, I also use plenty of sheet goods for
furniture and interior woodwork. I've done it for years and I'll continue.
Why the inconsistency? It has to do with my old-fashioned ideas of craftsmanship
and design, versus the real-world practicality of sheet goods. I just
can't pass up what they have to offer. Sheet goods are dimensionally stable,
strong, and consistent in thickness. Some types even look great, without
the need for heavy sanding. Here are my favorites and what they can do
for you.
Veneered Plywoods:
If you're building large cabinets or built-ins, then veneered
plywoods can help. They include a thin outer layer of good-looking, high-grade
veneer (1/64-inch to 1/32-inch thick), glued to a softwood plywood core
typically ranging from 1/4-inch to 3/4-inch thick. Most veneered ply comes
covered in hardwoods like birch, maple, ash, oak, cherry and walnut, but
you can get it in white pine, too.
There are three big advantages to veneered ply. Unlike
lumber, it's ready to use without the need for a jointer, planer or edge-gluing
operations. It costs about the same as an equal grade of solid wood, yet
doesn't expand and contract seasonally, so you can build in ways not possible
with lumber. On the downside, the core of veneered ply often contains
voids -- internal air pockets caused by flaws in the laminated layers.
Exposed edges are ugly, too, even without visible voids. That's why you've
got to cover them with strips of glued-on solid wood. Occasionally I've
also had trouble with the veneer peeling off due to a factory flaw, but
that's happened only twice in 12 years. Despite the drawbacks, veneered
ply has become a woodworking mainstay. It's my favorite for kitchen cabinetry,
especially when encased with a network of solid wood frames and panels.
The results are strong and good-looking on the inside, with attractive
solid wood where it counts outside.
Veneered Particleboard:
On the surface this stuff looks just like veneered plywood,
except it's 20% to 30% cheaper. It's also much heavier and doesn't take
nails or screws as willingly. Should you opt for particleboard's low cost
in exchange for these drawbacks? If your project is small, or destined
to be permanently mounted in a house (like kitchen cabinets), then yes,
it makes sense. But for large, portable furniture, you'll probably end
up cursing your stinginess next time you empty a room for painting or
move house. Another drawback of veneered particleboard is that scraps
aren't as useful for making jigs and fixtures in the workshop because
of that resistance to nails and screws I mentioned. You can still build
workshop doodads from particleboard, but it's not quite as fun. Particleboard
also contains more urea formaldehyde glue than veneered ply, increasing
the potential hazards of off-gassed fumes, especially during a Canadian
winter in a poorly ventilated home.
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Baltic Birch Plywood:
Who would have thought that the world's strongest, most
precisely manufactured sheet material is a product of the former Soviet
Block? Baltic birch ply is made entirely of 1/16-inch thick, flaw-free
hardwood laminations. It comes in metric thicknesses ranging from 3 mm
to 18 mm, all in quirky 5-foot x 5-foot sheets. If I had to choose a skid
of only one kind of plywood to take with me to my desert-island workshop,
I'd choose some 12 mm Baltic birch. Even the edges look good. The fine,
contrasting laminations always remind me of an All-Sorts candy.
You can't beat Baltic birch for drawer
boxes, small cabinet bodies and toolboxes. Its weird sheet size means
it's no good for floor-to-ceiling cabinetry, but hey, nothing's perfect
Particleboard:
This is simply the core of veneered particleboard, without
the pretty, hardwood face. It's an inexpensive, no-nonsense building material
for places that nobody sees. It's coarse textures means that after you
paint it, it still looks like particleboard. The only application where
it shines in the good-looks department is as a finished flooring material.
Shop-cut particleboard tiles -- with solid wood edging strips -- look
great and work well in dry locations. Just sand, stain and seal as with
any wood floor. Some people say it reminds them of cork. And at less than
60 cents a square foot, how can you go wrong?
Medium-Density Overlay (MDO) aka
Signboard: If you're painting a sign, making folksy standup silhouettes
for your lawn, or building painted gingerbread trim, this is the only
stuff you should use. MDO is a tough exterior plywood sheathed with a
layer of thick, all-weather paper. This outer layer is key. It eliminates
the cracking of surface veneers that happens on all other kinds of plywood
that's exposed tot he weather. Even marine-grade plywood develops tiny
surface cracks that'll undermine the integrity of paint, besides looking
terrible.
Medium Density Fiberboard (MDF):
This is a very fine-grained composite board that
mills crisply, takes paint willingly, glues well and costs little. In
fact, it's so finely textured that it carves nearly as well as basswood,
one of the world's greatest carving woods. But be warned: MDFs fine texture
also means it's very dusty when cut, routed or sanded. A vacuum system
is more than optional when working with MDF. The best way to join this
material is with biscuits and glue. You can use screws, but you'll need
to drill ample pilot holes in sheet edges to prevent splitting. If edge-splits
happen anyway, fix them by squirting glue into the open crack, while the
offending screw's still in place, then back the screw out and let the
glue dry.
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