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360/05 |
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NHLA RULES National Hardwood Lumber Association The sorting criteria were developed over 100 years ago by the American lumber industry and are now nationally and internationally recognised. They are the leading standard of hardwood classification worldwide. Unfortunately the measurement and the sorting of north American hardwood leads to misunderstandings when a European customer orders without having interpreted the NHLA rules exactly. A basic understanding of these rules is essential if American hardwoods are bought and processed. The following notes are regarded as help to the lumber purchaser and do not represent a claim on the complete content.
The cutting is grades as the grader finds it, i.e. complete length, width and thickness. Not graded are impurities that disappear after the processing of the surface (bark, beak damage from birds, etc.) At present 8 different standard grades which partly - depending on the sort of lumber - are interpreted differently. Below you will find the most common grades used for import:
FAS is the highest quality grade and No.3 Common the therefore corresponding lowest quality. Additionally there are a whole lot of special sorting which contents has to be listed in writing with each order. This includes here for example " 4 sides clear of defects" goods, Prime order a special colour requirement as for example No.1 & 2 White HARD MAPLE. (sorting for sap or "sap 1 face" or "white 1 face") For the quality definition the thickness of the board is a secondary role as both sides of the board decide the quality, where by always the lesser quality of the sides is classified, as the utilization of the board is defined by the lower characteristics. Therefore the so-called POOR FACE defines the quality. The only exception is the SELECT sorting (Picture 3). Here the GOOD FACE side is the base. A board of SELECT quality is selected from the better side as the quality FAS is selected and reaches the bad side at least of the No.1 Common grades. This exception was made in order for example in consideration of solid floorings. A further essential criterion of the NHLA rules is the exclusive grading of a board according to the whole material (mathematical: piece x length x width) yield “CUTTING METHOD”. A board corresponds to the FAS quality even if in the middle is a black knot with a diameter of 4”, as two clean sections can be made from the board (clear cuttings). The knot does not influence the 97% minimum use (Cutting units) according to the FAS requirement. (Picture 1). The additionally added knot size (picture 5) should not be more than 1/3 (Width x length in SM) of the surface, whereby the knots are measured in inch and the surface in feet. The quantity of knots does not matter. For example - depending on the kind of lumber - sap is not a fault. Prime and Comsel are qualities specially developed for export. Here is another interpretation range. Therefore it is important that supplier and purchaser agree to the required quality.
COMMENTARY CLEAR CUTTING: a clean section of a board, produced as rectangular or parallel cut to the length side of the board. Oblique or diagonal cuts are not permitted. CUTTING UNITS: a board consists of several clean sections. - Width in inch x length in feet = number of units - Size of knots: (picture 5) Essential here is the average added size of the knots of all knots = Length x width / 2 x quantity GRADING: the following order is applied:
SM: Surface measure => Width (inch) x Length (feet) / 12 = square feet TOLERANCES: Width => 90% should hold the minimum stated width.10% can be up to ¼” undersized. TECHNICAL KILN DRYING >KD<: Cracks and flaws caused by dryness are not regarded as faults. All qualities can have ¼” of the width as under measurement. Additionally a further 10% can have ½” under measurement. FAS/FAS 1 FACE: at least 1 Face FAS and better. COMSEL: FAS special sorting for export. => shorter and narrow pices as the rules allows * SPECIAL SORTING: are laid down between supplier and purchaser and should be put in writing into the Contract. |
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These sides are updated constantly. We are pleased about criticism, suggestion and your questions. In these cases, please call directly to Rolf Schäfer |
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