ENCYCLOPEDIA OF WOOD

PLYWOOD GRADING

he wide array of plywood types available makes choosing the appro­priate one for a project more involved than simply selecting a particular thick­ness. Both hardwood and softwood ply­wood panels are rated depending on how they should be used and on the appearance of their face and back veneers. They are also available in one of three grades, or durability ratings depending on the glues and veneers used in the construction of the panels. Softwood plywood comes in exterior and interior grades, and a category called Exposure 1.

Exterior-grade and Exposure 1 ply­wood are usually made with a water­proof adhesive, creating weatherproof panels that are resistant to moisture.

Their face and back veneers are cut from a relatively weather-resistant wood. Interior plywood is made with a water - resistant adhesive and is usually pro­duced with an appearance-grade face veneer and a lesser-grade back veneer. For most interior applications, wood­workers generally choose Exposure 1 or interior-grade panels.

The three hardwood plywood grades are Types I, II and III. Type I includes fully waterproof exterior panels while Type II is an interior-grade plywood able to withstand some moisture; Type III is a moisture-resistant interior plywood. Types II and III are your best choices for most cabinetmaking projects.

The appearance of the face and back veneers is another factor that distin­
guishes different plywood types. As shown in the chart opposite, both hard­wood and softwood panels are available in six grades. If you are buying softwood plywood you can determine its grade, plus additional information about a par­ticular sheet, by reading its grade stamp (below). Hardwood plywood is general­ly not stamped; if you need a particular grade, you have to ask for it and take the supplier’s word that you are getting what you want.

Plywood is manufactured in a range of sizes. Softwood plywood ranges in thickness from Vi to 3A inch, while hard­wood plywood is available from Vs to 1 inch thick. The standard panel size is 4 by 8 feet, but special orders can be placed for larger sheets.

DECIPHERING A SOFTWOOD PLYWOOD STAMP AND EDGEMARK

PLYWOOD FACE VENEER GRADES

SHOP TIP

A plywood carrier

Sheets of plywood, particleboard or hardboard can be heavy and awkward to carry. The carrier shown here will make the load easierto bear. Rout a 1-inch-wide rabbet along one face of a 12- inch-long board. Cut a notch out of one end of a piece of plywood, then screw a wood block across the end of the notch to serve as a handle. Attach the other end of the plywood piece to the rab­beted race of the board. To use the carrier, simply hook it under the lower edge of the sheet and pull it up under your arm.