Everything You Need to Know About Plywood
There's a lot to consider when purchasing plywood for a project. Check out this uber-comprehensive plywood buying guide.
When youre buying plywood or plywood sheets for any project, shop wisely. Your choices of plywood will have a huge impact on the building process and the results. This story will help you decide exactly what you need and help you avoid common plywood pitfalls.
Types of plywood: Veneer Core
Veneer core plywood is made up of many layers of hardwood bonded together. The layers are assembled with alternating grain direction, called cross-banding. This makes a strong, rigid, lightweight sheet with excellent screw-holding capability. Because of these qualities, veneer core is my first choice in most cases. Plus: Is plywood or OSB better? We’ve got the answer.
Types of plywood: MDF Core
MDF core plywood has a few advantages over veneer core. The thickness is more consistent; it machines well; the edges are solid, and MDF gives a smooth, even surface for the face veneer. Its also more stable and its typically flatter. However, MDF core plywood isnt as strong as veneer core, it doesnt hold fasteners as well and its heavy. But if Im making one-piece doors, Ill choose MDF core plywood sheets every time because of its flatness and stability.
Types of plywood: Particleboard Core
Particleboard core plywood is the least expensive option. Like MDF core, its flat and stable with consistent thickness. But particleboard core plywood is a bit worse in the screw-holding category. Also, its a special-order product, at least from my lumberyard, whereas MDF core is readily available.
Types of plywood: Combination Core
Combination core plywood weds the best attributes of MDF core and veneer core. The center cores are cross-banded hardwood, providing strength, light weight and screw-holding capability. The outer cores are MDF, giving a flat, uniform surface for the face veneers. However, combination core plywood is a compromise: It doesnt have the screw-holding capability and rigidity of veneer core, or the flatness and stability of MDF core. Next, check out our thorough guide to all things treated lumber.
Types of plywood: Lumber Core
Lumber core plywood consists of edge-glued strips of wood, usually basswood. On both sides of the core, theres a cross-banded veneer, then the face veneer. Like veneer core, it has excellent screw-holding capability, strength and rigidity. But its considerably more expensive and harder to find than veneer core, so I almost never use it. However, this plywood a good choice for long shelves.
Types of plywood: Baltic Birch and Appleply
Baltic birch and ApplePly plywood are top-notch veneer core plywoods, which youll only find at a lumberyard. Their 1/16-in.-thick core veneers offer better stability than typical plywood with 1/8-in.-thick core veneers. The raw edge is attractive when finished and often used as a design element. Baltic birch or ApplePly plywood is my first choice for drawers and shop jigs. ApplePly is available in thicknesses from 1/4 in. to 1-1/2 in., and in many face veneer species.
How veneer is cut: Rotary Cut
Rotary-cut veneer is peeled from the log like paper towels from a roll. It produces a wide, loud grain pattern.
Check out our best tips for working with self-leveling underlayment.
How veneer is cut: Plain-slicing
Plain-slicing produces a repeating pattern, typically showing large cathedrals in the grain.
Check for plywood flatness
Dont expect perfectionyou probably wont find it. Just try to find the best of the pile. Sight down all the edges just like youd do if you were buying 2×4 studs. Sometimes, plywood sheets are warped in multiple directions, resembling a potato chip. Leave these for some unlucky, less-informed buyer. If youre buying 1/4-in. plywood, dont worry about flat and straight; it wont be either. But youll likely fasten it to structural parts, which will keep it flat.
Inspect the edges
Examine the edges of plywood and inspect the different layers of veneer. They should be straight and of uniform thickness and have few, if any, voids. If you see a lot of voids, there’s sure to be more throughout the sheet that wont be visible until you cut it.
And avoid overlaps. On high-quality plywood sheets, core veneers are each one piece, or one full layer. But sometimes on less expensive plywood, two or more pieces are used to make up a single layer. Instead of being cut to fit each other where they meet, the edges overlap and are just pressed to the thickness that that piece of core veneer is supposed to be. This can result in an undulating surface.
Watch for buried treasure
The most beautifully figured face veneers will be at the lumberyard. But when Im at the home center, I like to check out the back faces of the plywood or even plywood thats meant for underlayment. Because most people look for consistency of color and grain, there are some striking veneers that get written off as ugly. Quite often, something catches my eye that could be a really cool design element.
Can you special-order plywood?
Some home centers will special-order many different species, core options and veneer cuts. But beware: You wont be able to look at the actual plywood sheets before buying, and you probably wont be able to return or reject them unless theyre damaged or otherwise unusable. If its just that you dont like the grain pattern, youre probably stuck with it. Also, there may also be a minimum quantity you need to buy.
Shopthe home center for convenience and savings
Baltic birch is a premium plywood found at lumberyards. A 3/4-in., 5 x 5-ft. sheet has 13 core veneers and costs about $70. Some home centers carry a similar product, called classic birch. A 3/4-in., 4 x 8-ft. sheet has 10 core veneers and costs $50 to $60. Its strong with good screw-holding capability, making it a good, affordable alternative. Its perfect for less visible cabinet parts, drawers and shelving. As for other plywood sheets, home centers have a more limited selection, carrying mostly veneer core (maybe MDF core), grade B2 and lower. Face veneer cuts are typically rotary cut or plain sliced, and in-stock species will usually be red oak, birch and maple. But the home center is a good option to save a little money.
Which plywood can you paint?
For projects Im going to paint, I like MDF (medium-density fiberboard) or birch. B-grade birch or lower is fine. Sometimes, youll even see plywood classified as paint grade. Birch is close-grained with a smooth texture that doesnt show through paint. With an open-grained species like oak, the grain is visible under paint. MDF, of course, has no grain pattern, making it a good choice for painted projects. But for structural parts, I like birch veneer.
Can you sand plywood?
All plywood needs at least light sanding before finishing. Sometimes, the face veneer on home center plywood is so thin that the pink veneer adhesive shows through. On several occasions, Ive had birch veneer turn translucent after light sanding with 220-grit paper.
If you suspect that the veneer is ultra thin, dont use a power sander. Just sand by hand.
How to get the bow out of plywood
Admit it: Youve tried flattening sheets of plywood. I have too. Ive tried weights, clamps, wetting down the concave side, sun-drying the convex side and gluing opposing bowed sheets together. Nothing seems to work with any reliability. If the core veneers werent in a perfect state of equilibrium and all in harmony when they were bonded together, the sheet has little chance of flattening out. The only recourse is to save the flattest sheets for the largest parts and use the worst sheets in smaller components, minimizing any curvature.
Watch out for plywood damage
You can often cut around minor damage in an otherwise good plywood sheet (if you can, you might even be able to get a discount). But sanding out deep dents (above) isnt an option. You may not be able to sand out stains either. The purple stains shown result from a reaction between oak tannin and steel.b