In 205, you will learn how the various defects from the manufacturing process can be applied to the NELMA grades. Manufacturing imperfections, though allowed in the grades, are not typically desired by the end user. A grader should notify the planer operator or manager when any of these imperfections are occurring frequently.
Torn Grain is an irregularity in the surface of the piece where wood has been torn or broken out by surfacing. The limitations for each grade are listed below.
| Grade | Allowable Depth |
| C Select | Not Permitted within Grade |
| D Select | Very Light (up to 1/64” depth) |
| Finish | Very Light (up to 1/64” depth) not over 5% of face |
| Premium | Medium (up to 1/16″ depth) not over 10% of face |
| Standard | Medium (up to 1/16” depth) |
| Industrial | Not Limited by Grade |
Raised Grain is a roughened condition of the surface of dressed lumber in which the hard summerwood is raised above the softer springwood, but not torn loose from it. The limitations by grade for this defect are listed below.
| Grade | Allowable Depth |
| C Select | Very Light (not over 1/64″) |
| D Select | Very Light (not over 1/64″) |
| Finish | Very Light (not over 1/64″) |
| Premium | Light (not over 1/32″) |
| Standard | Light (not over 1/32″) |
| Industrial | Not Limited by Grade |
Mismatch is an uneven fit in worked lumber when adjoining pieces do not meet tightly at all points of contact or when the surface of adjoining pieces are not in the same plane. See the table below for grade limitations.
| Grade | Allowable Mismatch |
| C Select | Very Light (not over 1/64″) |
| D Select | Very Light (not over 1/64″) |
| Finish | Very Light (not over 1/64″) |
| Premium | Very Light (not over 1/64″) |
| Standard | Very Light (not over 1/64″) |
| Industrial | Not Limited by Grade |
Skips are areas on a piece that failed to surface clean. The limitations by grade are listed below which include the terms “Hit and Miss” and “Hit or Miss”. For instructions regarding these terms see the video within this section.
| Grade | Allowable Skip |
| C Select | One Light (not over 1/32″) 2′ Skip per each 8’ of length on reverse face. |
| D Select | Hit and Miss on reverse face OR one edge |
| Finish | Hit and Miss (not over 1/16″) on reverse face OR Light skip (not over 1/32″) on one edge not exceeding 1/4 the length. |
| Premium | Hit and Miss (not over 1/16″) on reverse face or on one edge |
| Standard | Hit and Miss (not over 1/16″) on reverse face; one edge may be 1/16” (Medum) scant full length or 1/8” (Heavy) scant for half the length |
| Industrial | Hit or Miss (not over 1/16″) or a Heavy (not over 1/8″) skip not exceeding 1/4 the length. |
Offset is an abrupt dressing variation in the edge surface which usually occurs near the end of a piece without reducing the width, or without changing the plane of the wide surface. The allowable offset by grade is described in the table below.
| Grade | Allowable Offset |
| C Select | Very Light (not over 1/64”) in 2% of pieces |
| D Select | Medium (not over 1/16”) in 2% of pieces |
| Finish | Light (not over 1/32”) in 2% of pieces |
| Premium | Very Light (not over 1/64” ). 2% of pieces may have Medium (not over 1/16”) |
| Standard | Very Light (not over 1/64” ). 2% of pieces may have Heavy (not over 1/8”) |
| Industrial | Not Limited by Grade |
Knife Marks are imprints or markings of the machine knives on the surface of dressed lumber. Slight is defined as readily visible, but evident; no unevenness to the touch. See table below for allowances by grade.
| Grade | Allowable Knife Marks |
| C Select | Slight |
| D Select | Slight |
| Finish | Slight |
| Premium | Slight |
| Standard | Not Limited by Grade |
| Industrial | Not Limited by Grade |
Marks that are more uneven dressing than knife marks. Easily visible on the surface of the board; unevenness to the touch. See limitation by grade below.
| Grade | Allowable Wavy Dressing |
| C Select | None Allowed in Grade |
| D Select | None Allowed in Grade |
| Finish | None Allowed in Grade |
| Premium | None Allowed in Grade |
| Standard | Light (not over 1/32″) |
| Industrial | Not Limited by Grade |
Machine Burn is a darkening of the wood due to overheating by the machine knives or rolls when pieces are stopped in the machine. See tolerances by grade in the table below.
| Grade | Allowable Machine Burn |
| C Select | None Allowed in Grade |
| D Select | One per board |
| Finish | None |
| Premium | One per board |
| Standard | Not Limited by Grade |
| Industrial | Not Limited by Grade |
Machine Bite is a depressed cut of the machine knives at the end of the piece. See table below for the limitations by grade.
| Grade | Allowable Machine Bite |
| C Select | Very Light (not over 1/64”) |
| D Select | Very Light (not over 1/64”) |
| Finish | Very Light (not over 1/64”) |
| Premium | Very Light (not over 1/64”) |
| Standard | Very Light (not over 1/64”) |
| Industrial | Not Limited In Grade |
