(Nearly) All Woodwork Depends on Glue

Most of us have a lot more idealism in us than we realize. This is not necessarily a bad thing.

However, at times it can be a severe liability. It can make us susceptible to sales tactics that recognize and exploit those idealisms. Generally, when you are about to make a major purchase like a car or a kitchen remodel, you want to shed any simplistic notions you may have and find out “the real deal” about whatever it is you are buying.

In this case, I'm talking about buying cabinetry. Should you insist upon your cabinets being made of bona fide solid wood or is it okay if they are made of plywood? What about particle board or MDF? Plastic? Foam? Cardboard? (Don't laugh — I've seen it all)

Elsewhere in this blog I've written about the use of the term “solid wood” by salespersons. This is an example of an attempt to capitalize on your simplicity and idealism.

What idealism, you may ask?

To a normal, well-educated person with no background in wood working, it might seem self-evident that the best quality in a cabinet or furniture would be found in pieces made from solid, uncut pieces of wood, taken straight from the tree.

If you've seen the movie “Meet the Parents”, you've seen a telling reference to this notion. As a way of showing us just how wonderful the bride's previous boyfriend is, it shows the boyfriend in his shop, finishing a large, vine-covered gazebo, carved entirely from a single piece of wood. Later in the movie, the bumbling groom manages to torch this priceless masterpiece.

The truth, as usual, is a lot more nuanced. You really wouldn't want a gazebo carved from a single piece of wood. It would fall apart very quickly after its construction was complete.

(Now, I will admit that there are a few pieces of woodwork in a house that do not depend on glue. Generally, these would be narrow or small pieces that actually are taken from a single piece of wood. One example would be the railing spindles in your staircase if you have stained spindles. In some cases, though, a close inspection may reveal that even those are glued-up from multiple pieces of wood.)

Solid Wood, and by that I'm meaning pieces of natural wood bigger than an adult thumb, gets “glued up” into panels or joined up into frames for doors or cabinet “face frames”. All of these applications depend on glue. Over time, many of these joints (I'm guessing somewhere around 10%) will develop cracks due to the unpredictable combination of wood, time, and moisture.

Plywood is thin layers (usually between a sixteenth and an eighth of an inch) that are glued together to form large sheets, usually 4'x8' size. How are such large (albeit thin) pieces of continuous wood possible? A large log is spun as a long knife cuts into them from the side, creating a thin sheet of wood that can be easily uncurled and mated together with sheets that want to curl the opposite way. The other important detail is that the sheets are mated so that the grains in each layer run perpendicular to the grains in its adjacent plys. This means it's not weak in one direction, like uncut wood.

Plywood is really a marvel of modern engineering. It results in lightweight pieces of wood which are very strong in all directions. Plywood is far less susceptible to warping or splitting compared to solid wood. Usually the plys will be made of poplar and then a thin layer of another wood will be put on the outside. This veneer is what you see — oak, maple, etc…

Having installed hundreds of kitchens, I can tell you that I feel VERY good about the longevity of the plywood cabinets I've installed.

Particle Board uses lots of glue to hold particles of wood together. The particles have an average size that is a bit smaller than an apple seed. PB is heavy and brittle, and because its lumpy, you can't put a veneer of real wood on it, so usually it is faced with a plastic or paper. If you see a cabinet that seems to have only a “picture of wood” on its side, it's probably particle board with a thin paper facing. High-end particle board cabinets actually have a plastic facing — you'll hear it called “laminate”. Particle board is the definite winner in the cheapness category.

MDF is just like particleboard except that the particles are tiny and dust-size. It has all the properties of PB except that it isn't lumpy, so it can be sanded or get a veneer of real wood on it. I've seen million-dollar new houses with MDF crown, base, and built-in cabinets. (Not necessarily a good thing.)

Extruded Foam might be a good choice for exterior (outside of your house) trim, but don't let it inside the house. Its made of … foam. It's not really even woodwork, so why am I writing about it?

Here's the point: all woodwork depends on glue, so ultimately it is the structural and cosmetic properties of the woodwork that should concern you, not the question of whether it's “solid wood.”