March, 2017

SCHALLER HARDWOOD LUMBER CO.

HARDWOOD PLYWOOD GRADES & CORES

 

Hardwood plywood uses two alphanumeric characters to designate the grade of the panel.  The first character refers to the quality of the face of the panel.  This character is normally a letter-such as “A”.  The second character is normally a number and refers to the quality of the panel back.  A typical plywood grade would be A-1.  This means that the plywood would have an “A” grade face with a “1” back.  This is typically the grade most often used in 1/2” and thicker panels for cabinet work.  The most common used grade in 1/4” plywood is A-4.  This means the plywood will have an “A” grade face with a reject or mill option back.  A brief summary of the specifications of each face grade and back grade follows:

 

A GRADE—Will generally be matched across the panel for both grain and color.  An “A” grade face will permit a maximum of ten pin knots or small burls combined.  It will not permit sound knots, repaired knots or rough cut veneer.  It does allow slight mineral streak and/or vine marks.  This is the face grade most often used for fine cabinet or millwork.

 

B GRADE—Will generally be matched for pleasing color, but not necessarily for grain.  “B” grade faces will permit a maximum of 16 pin knots and small burls combined of which 50% may be up to 1/4” diameter.  “B” face will also permit four sound or repaired knots and some slight rough cut veneer.  A “B” face will also allow slight mineral streak and vine marks.

 

C GRADE—Will allow unlimited pin knots and small burls.  Can contain up to eight repaired or sound knots up to 1/2" in diameter.  Allows unlimited mineral streaks and vine marks.  This grade is most often used for paint grade type panel or in lower end case work.

 

D GRADE—Will allow unlimited pin knots and small burls.  Can contain up to ten repaired or sound knots of which 50% may be 3/4" in diameter.  Also allows unlimited mineral streaks and vine marks.  5% of the panel may be of rough cut veneer.

 

“1” BACK—Can contain up to 16 sound tight knots not exceeding 3/8” in diameter.  Allowed to contain unlimited mineral streaks.  It will not contain any repaired knots.  This is generally the back grade most often paired with an “A” grade face on panels exceeding 1/2" in thickness.

 

“2” BACK—Can contain up to 16 sound tight knots not exceeding 3/4" in diameter.  It can contain repaired knot holes, rough cut veneer, and mineral streaks.

 

“3” BACK—Normally not used in any of the plywood Schaller Hardwood stocks.

 

“4” BACK—Generally referred to as a reject back.  It is meant to be used in concealed areas where appearance is of no concern.  This grade back is most commonly used on 1/4" plywood.  It is also used on some of the thicker panels when the panels are being used  for an application such as wall paneling.

 

DEFINITIONS OF VENEER CUTS

 

ROTARY/CUT—.Rotary/cut veneer is produced when the log is centrally mounted on the veneer lathe and turned against the knife.  The veneer is peeled in long sheets similar to unwinding a roll of paper.  A wide variegated grain pattern is the result.

 

PLAIN SLICE—Plain Slice veneer is produced by parallel slices through the center of the half log.  Grain resembles that of sawn lumber.

 

 

VENEER MATCHING

 

BOOK MATCH—Every other sheet of a flitch is turned over, just like the pages of a book.

UNMATCHED—Flitches of veneer are assembled with no definite pattern of grain characteristics

WHOLE PIECE FACE—The panel face is made from a single piece of veneer, exposing a continuous grain across the entire panel.

 

CORE DESCRIPTIONS

Hardwood plywood is manufactured using three components, a face veneer, a back veneer, and a core stock.  The core of hardwood plywood will normally be one of four types, veneer core, medium density fiberboard, particleboard, and lumber core.  A brief description of each follows:

 

VENEER CORE (V.C.)—This is a standard veneer crossbanding technique wherein three, five, seven or nine veneer plys are used to produce the final panel

 

LUMBER CORE (L.C.)—This is a five ply construction made up of two face veneers, two cross band veneers and a solid lumber core.  The core is usually made up of edge glued strips of lumber 1-1/2” to 2” in width.  The core is basically solid and free of voids which give unusual strength and high resistance to buckling, twisting or warping.  Panel thickness is normally 3/4".

 

PARTICLEBOARD CORE (PBC)—This is a carefully engineered product.  Thickness tolerances are maintained to a maximum deviation of + or - .005”.  Particleboard core is available in thickness from 1/4" to 1-1/2” and various widths.  Fire Retardant particleboard is also available in a wide variety of sizes and thicknesses.

 

FIBERBOARD CORE (MDF)—Similar to particleboard core with the additional advantage of uniform density throughout the panel.  Available in thicknesses from 1/4" to 1-1/4” and various widths.  Edges can be machined and easily finished.  Fiberboard is the most stable of composition core materials.

 

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