Knotty/Rustic
Knotty or Rustic Grade wood is known for having more knots of every variety compared to their Select alternative. In this grade, knots can range from covering the piece to only a few dotting the piece and there is no restriction to how many or few knots there are and their size. Knots, their density, and their types will be associated with which species of wood the piece is constructed with. Sometimes knots may be filled or reinforced to ensure quality, but this is not guaranteed and is under the discretion of the millers.
Select
Select Grade, also sometimes called “Clear,” is characterized by having fewer and smaller knots if any. Select grade minimizes the amount of knots on a piece and how distinguished they may be. Any open knots are filled and reinforced to ensure the surface quality. Rift-cut and Quarter-sawn cuts of wood are always chosen to be Select Grade and thus also have the same restrictions normal Select Grade wood has regarding knots.
Other
Some wood species such as Wormy and Birds Eye Maple are graded as rustic due to their unique structure of knots and rustic characteristics such as the natural worm holes in Wormy Maple. These woods can have traditional knots along with their distinct characteristics and are not required to minimize normal knots in each piece. Again, knots may be reinforced or filled to ensure quality, but this is not required.
Flat-cut
Flat-cut is the cut associated with normal, Knotty or Rustic, and Select grades of wood as it is both the most traditional and efficient sawing method. Flat-cuts are achieved by horizontally slicing a log into a series of flat boards. This technique wastes the least wood and can be recognized for its tangential grain, which is also called flame or cathedral due to its shape.
Quarter-sawn
Quarter-sawn wood is characterized by its far straighter grain pattern and flecks. Quarter sawn wood is generally more expensive and time consuming to produce but can be resistant to warping present in Flat-cut woods. Quarter-sawing is achieved by quartering the wood and sawing each plank nearly perpendicular to the grain. While this cut type wastes more, in certain species such as oak, it can cause flecks which shimmer and are often prized in certain looks.
Rift-cut
Rift-cut wood has many similar characteristics to Quarter-sawn wood with its straight grain. Rift-cut woods contain less flecks than those present in Quarter-sawn lumber due to cutting perfectly perpendicular to the grain. This technique creates the most waste of the three but produces the straightest grain and most warp resistance of the three with minimal flecks compared to those found in Quarter-sawn wood.
