These grades primarily indicate the quality of the face veneer on the plywood’s surface. For hardwood plywood, ‘A’ is the highest quality, suitable for clear finishes, while ‘D’ is the lowest.

• Grade A: The highest quality face veneer. Very smooth, sanded surface, free of knots, patches, or repairs. Ideal for visible surfaces that will be painted or clear-finished, commonly found on high-end cabinetry and furniture.
• Grade B: Smooth, sanded surface, but may have minor blemishes, small, tight knots (typically up to 1 inch), and some well-done repairs (patches). Still good for painting or surfaces where minor imperfections are acceptable.
• Grade C: Unsanded, with visible defects like knots (up to 1.5 inches), knotholes (up to 1 inch), splits, and discoloration. Used for structural purposes where the appearance isn’t critical, such as subfloors.
• Grade D: The lowest quality, unsanded, with larger knots (up to 2.5 inches), unrepaired knotholes, splits, and other significant defects. Used for hidden structural purposes or where appearance is entirely irrelevant.

For hardwood plywood, the back veneer is graded with a number, where lower numbers indicate better quality. These backs are usually less critical for appearance than the face veneer.

• Grade 1: Very good quality back veneer with minimal sound defects, similar to an “A” face in appearance but might allow for very minor characteristics. Suitable when the back will be visible.
• Grade 2: Good utility grade, allowing for more minor defects than a ‘1’ back, such as small sound knots or minor discoloration.
• Grade 3: Allows for larger sound knots, some repairs, and more noticeable natural characteristics. Suitable for backs that are less visible.
• Grade 4: The lowest quality back, allowing for larger open knots, splits, and other significant defects. Often used when the back will be completely hidden.

Example: A plywood panel graded A-2 indicates it has an A grade face (highest quality) and a 2 grade back (good utility quality, allowing some minor defects).

These terms describe the construction of the core layers within the plywood, which significantly impacts its strength, weight, stability, and screw-holding ability:

• V/C (Veneer Core): Composed of multiple layers of wood veneer (plies) glued together with alternating grain directions. Offers good strength and stability, generally lightweight. The quality can vary based on the number of plies and absence of voids (gaps) in the inner layers. Commonly used in furniture, cabinetry, and general construction.
• L/C (Lumber Core): The core consists of solid lumber strips glued edge-to-edge, with crossband veneers on both sides, and then the face and back veneers. Offers excellent strength, flatness, and screw-holding capabilities. Typically used in high-quality furniture, doors, and panels where stability and rigidity are crucial.
• MDF/C (Medium-Density Fiberboard Core): The core is made from medium-density fiberboard (MDF), a fine-grained, uniform composite material. Provides a very smooth, consistent surface, ideal for thin veneers or painting as it reduces “telegraphing” (imperfections showing through). However, it is significantly heavier than veneer or lumber core and has lower screw-holding power. Often used in cabinetry and architectural panels.
• P/BC (Particleboard Core): The core is made from larger wood particles bonded with resin. Generally the most economical core option and offers flatness, but it is the heaviest and has the weakest screw-holding power compared to other core types. Used where cost is a primary concern and the core won’t be exposed.
• Combi-Core (Combination Core): A hybrid core, typically using veneer inner plies for strength and stability, but with MDF or particleboard layers directly beneath the face and back veneers. This combines the strength and screw-holding of veneer core with the smooth, void-free surface of MDF/PB, minimizing telegraphing of core defects to the face veneers.

These classifications indicate the plywood’s resistance to moisture and its suitability for various environmental conditions:

• INT (Interior): Made with glues suitable for interior use only, where moisture exposure is not expected.
• EXP 1 (Exposure 1): Made with exterior-type glues and suitable for applications where temporary exposure to the elements during construction may occur. This is often seen with CDX plywood, where the “X” refers to the exterior glue. It is not intended for permanent outdoor exposure.
• EXT (Exterior): Made with waterproof adhesives designed to withstand repeated wetting and redrying or long-term exposure to weather or high humidity. Suitable for permanent outdoor structures and applications where constant moisture exposure is expected. Often features higher quality veneers (Grade C or better throughout the panel) compared to Exposure 1.

Marine grade plywood is manufactured to high standards for applications requiring superior durability and resistance to moisture, typically in boat building and other marine environments. Key characteristics include:

• Void-Free Core: Inner plies have very few or no voids (gaps), which prevents water from collecting and causing delamination or rot from within.
• Waterproof Adhesive: Uses highly water-resistant (WBP – Water Boil Proof) phenolic resin glues, ensuring the plies remain bonded even when submerged or subjected to extreme moisture.
• Durable Species: Often made from naturally durable species like Okoume, Meranti, or Douglas Fir.

Common standards for marine grade plywood include British Standards:

• BS 1088: This is the higher and more stringent British Standard for marine plywood. It specifies a very high quality of veneers throughout the panel (typically A-grade or very close), minimal or no core voids, and uses extremely durable species and waterproof glue. It’s intended for critical structural applications in boats.
• BS 6566: While officially superseded by European standards like EN 315/EN 636, BS 6566 was an earlier British Standard for exterior plywood that was sometimes considered “quasi-marine” or suitable for non-structural marine parts above the waterline. It allows for more blemishes in face veneers and some filled core voids compared to BS 1088, but still requires waterproof glue. It’s generally a lower grade than BS 1088 in terms of veneer quality and void tolerance.

These designations refer to additional treatments applied to the plywood surface:

• G2S (Good Two Sides): Both sides of the plywood have a high-quality finish, usually indicating both are Grade A or B. Used in projects where both sides of the plywood will be visible.
• UV1S (Ultraviolet One Side): One side of the plywood is coated with a UV-cured finish, which provides a durable, clear coating that protects the wood. Used in cabinetry and shelving where only one side needs to be finished.
• UV2S (Ultraviolet Two Sides): Both sides are coated with a UV-cured finish, offering protection and a finished appearance on both sides. Ideal for furniture, cabinets, and other applications where both sides are visible and need to be finished.

These terms describe how the veneer layers are cut from the log, influencing the grain pattern and appearance:

• PS (Plain Sliced): Also known as “flat cut.” The log is sliced parallel to the center, creating a distinct “cathedral” or flame-like grain pattern, especially noticeable in oak. Often used in high-end furniture and cabinetry for a classic wood aesthetic.
• RC (Rotary Cut): The log is rotated against a stationary knife, peeling the veneer in a continuous sheet. This produces a wide, bold, and often wild grain pattern that can vary significantly across the sheet. Commonly used for general-purpose plywood, construction-grade panels, and sometimes for inner plies.
• Qtr. Sliced (Quarter Sawn): The log is first cut into quarters, and then the quarters are sliced perpendicular to the growth rings. This produces a straight, tight, and uniform grain pattern, often with “fleck” (medullary rays) in woods like oak. Used for high-end architectural panels and fine furniture where a refined, consistent look is desired.