Buying lumber from a lumber yard can be intimidating, but surely plywood is simpler... right? Plywood is a manufactured product that has a more controlled process and standardization then harvesting lumber, but there are still a lot of variations in plywood that makes buying plywood more complicated then if you were to buy a PlayStation off the shelf.
I don't buy plywood frequently, each time I do I have to refresh myself on all the different terminology and options that I get back from the lumber dealer so I decided to write a post to myself to save my time re-searching the internet on what each thing means.
Core Materials
Plywood is made of layers of wood materials sandwiched between the wood veneers that gives it's look. Walnut plywood is made from two walnut veneers with enough the material ("core") between them until it is the thickness desired. The layers gives plywood its stability and not have the wood movement that lumber typically have.
Face and Back Grades
The face and back of plywood have grades that describes its quality:
Face grades:
AA - Premium, architectural quality for interiors, case goods and high end furniture.
A - Not as high as AA but still excellent appearance.
B - Less perfect and consistent than A panels but more economical.
C - More defects and variations. Not as attractive so good for less visible applications.
"Shop" grade - Panels that have some imperfection that causes the sheet to not meet the grade (e.g. A1 or C2).
Back grades
These goes from 1 (best) to 4 (worst). Grade 3 & 4 allows for open defects.
Baltic Birch Grades
Baltic Birch uses a different grading system:
B/BB - one face free of "footballs".
BB/BB - An average of 4 to 6 footballs per face
BB/CP - An average of 4 to 6 football on one face and unlimited footballs on the back
(BB/CP example)
Veneer Core
Veneer core means the odd-number of layers between the face veneers are made of sheets of wood layered in alternating grain direction for stability. Lighter and have strong screw holding power, but might not be as flat if there are imperfections in the core layers which can show through (aka "telegraph").
There are processes to address this such as Columbia Forest Product's MPX core to make veneer core smooth and reduce telegraphing. MPX is Columbia's registered trademark for basically using smooth hardwood crossbands in the core to smooth out the veneer.
MDF Core
MDF core consists of using medium density fiberboard between the face veneers which is very stable and uniform. MDF can be heavy and can swell up and dissolve when wet.
Combination Core
This core uses a combination of MDF and wood veneers between the faces.
Veneer Cuts
The way the veneer is cut effects the appearance, properties and cost of the veneer. For example, plain sliced cuts produces veneers with the "cathedral" patterns while a quarter cut produces a more thin line pattern.
A rotary cut can produce Whole Piece Face (WPF) veneer where the entire face of the plywood is a single piece of veneer and can be more economical to produce. In order to make a full sheet of plywood from the other cuts, the strips of veneer of placed side-by-side so there can be a fine seam between the strips. How the strips are placed is called matching which is discussed more below.
Veneer Match
Unless it is a whole piece face, the veneer panels needs to be placed side-by-side in order to crate a full piece of plywood. How these panels are ordered is what is called veneer matching. There are multiple ways to do this and I provide some links in the references below that describe them but the common ones are:
Slip Matching
Slip matching places each panel next to each other without turning or flipping them over. This creates a repeated look.
Sequence Match
Sequence match requires that the panels come from the same log and be more consistent panel-to-panel.
https://awiqcp.org/news-and-blog/wood-veneers-matching/ -- sequence matching have a higher standard for matching more then slip (which is also layers it in sequence.
