What is the best plywood for cabinets?
Plywood is an engineered wood that is manufactured from thin sheets of veneer and glued into layers to provide maximum strength and resistance to shrinking and expansion. The exposed outside layers of cabinet grade plywood are typically thin veneer sheets that are less than 1/16th of an inch thick. Plywood cores make up the majority of the thickness of sheet goods.
Veneer Core: Always has an odd number of veneers that alternate grain directions to provide a strong panel that can withstand large loads and has incredible bending strength.
Particleboard Core: Is typically chips of wood that are compressed and glued together, depending on the size of the chips used it can create very flat and stable surfaces that are good for veneering. If this material gets wet it will dissolve to an oatmeal consistency. It is a cheap material that is commonly used for semi custom cabinets throughout a home.
MDF Core: Can be produced with a consistent and uniform thickness compared to any of the plywoods available in the market. It provides a very flat surface for wood veneers to adhere to. This particular core is great for creating large door panels for cabinets because it tends to resist warping.
Lumber Core: One solid slab of wood that has veneers placed on either side of the wood core. This core provides great strength, and is commonly used for long open shelving in closets.
Combination Core: This core is a combination of veneer core and MDF core. Most commonly constructed with an outside veneer, MDF layer, working our way to the center with a few plies of wood veneer at its core. The benefit to this construction is that you get smooth consistency for the veneer to adhere to, while also getting the good screw hold capabilities.
For cabinets, the most commonly used plywood’s are Birch, Maple, Oak, and Walnut. Birch tends to be used as paint grade, but can also be used as a stain grade if there is a specific budget to meet. Maple, Oak, and Walnut are always used for stain grade, this material is almost always double if not triple the cost of Birch ply.
There are four grades of plywood in regards to the outer veneer: A, B, C and D grades. A grade has the highest quality and is the most expensive, and D grade is the least expensive with large defects.
A-grade plywood features a smooth, sanded surface without knots. Any wood defects have been repaired with synthetic wood filler, so the veneer can be painted or stained. A-grade plywood is ideal for furniture or cabinet doors.
B-grade plywood also features a smooth, sanded surface, but may have more repaired defects up to 1-inch across. In most cases this is a perfect option for paint grade plywood because the filler that is used provides a permanent bond to the material.
C-grade plywood is not sanded and may have several minor defects that will need to be repaired with knots up to 1 1/2 inches across, discoloration and sanding defects. C-grade plywood should be used when appearance is not important, such as for subfloors or garages. If you have C grade being used for cabinet production, odds are it is structural and will never be seen. I find that C grade paints well, but extra filler is needed to repair the surface, and there is more sanding the material has to go through in order to get the same results as B grade.
D-grade plywood is not sanded with defects that have not been repaired and knot holes up to 2 1/2 inches across, discoloration and various defects. This material is never a consideration for cabinet making.