Plywood Veneers Dictate Grade
The face veneers are what we see and therefore it is what determines the grade of a sheet of plywood. Plywood veneers must be peeled and dried to a 100% consistent moisture content so that they lay down smoothly on a plywood core. Moreover when the moisture from glue is added to the mix, the plywood veneer needs to react uniformly so consistent thickness and absorption is imperative. These veneers must be sanded to exact thickness and consistent sanding grit to set the glue absorption rate.
Plywood grade for hardwood plywood will be a letter and number designation like B2 or A1 where the letter is the front face and the number is the back face. An A face and a 1 face while the top of the grade are not the same quality as back faces allow more defects and patches. The grade has nothing to do with the quality of the veneers in the core but it is also common to expect that a higher quality core will accompany a higher grade face veneer. BUT this is not demanded by the grade! Its unlikely for sure, but it has been done as a way to save on cost for a panel.
Types of Plywood Veneer
Beyond the species of the veneer, how it is cut from the log, how it is arranged on the core, and how it is spaced will all dictate the type and cost of the finished panel. Often only the grade will be mentioned on a price sheet but if you know how veneers are laid onto a core you can ask questions about these aspects to get a better feel for what your panel will look like. It also useful to determine a price difference between two sheets on a price list.
- Rotary cut plywood is most common where the log is peeled in one long sheet. This results in the least amount of waste and no seams.
- Plain Sliced is sliced with a guillotine style blade the same way a plain sawn log is cut into boards. Here we have seams between the leaves of veneer as each is equal to the width of the log.
- Quarter Sliced is again just like quartersawn boards where the log is angled then sliced so that the growth rings intersect the face at 90 degrees. Much more waste is incurred here and the process is more time consuming but the match on the face is beautiful with medullary figure evident in certain species.
- Rift Sliced also like a rift sawn board wher the log is oriented and sliced so that the growth rings intersect at 45-60 degrees to the face. Here we have perfect straight or vertical grain with no medullary ray fleck. Often a common veneer slicing method for composite flooring where figured stands out and straight grain is preferred.
Once the veneer is peeled from the log and dried and sanded, how it is assembled on the core is just as important to the look of the panel. Bookmatched, sequence matched, running match, center match,etc all dictate how these veneers look. These all combine to tell you how your panel will look. So instead of buying A1 Cherry Plywood, you can impress your friends and inform your dealer when you ask for an A1 Quartered, Bookmatch, Center match panel.
Recognizing that this can get confusing fast, if you use a lot of plywood I highly recommend that you pick up a copy of the Hardwood Plywood Handbook put out by HPVA.
Make sure you check out Part 1 of this plywood series to get a better idea about plywood pricing and how all the elements of a panel come together to change your price point.