Simonburrows":2d2a7fka said:
do you think the "Pith Fleck" comes into acceptable grading?
Simon
If it is American ash, which I think it probably is then you might find these American grading rules a useful guide. Slainte.
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Grading is based on the length and width of defect free pieces (cuttings) that a board will yield. This judgement is made by viewing the wide faces of a board. The clear cuttings are assessed from just one face, with the exception of the First and Seconds (FAS) grade which is judged by inspecting and grading both faces. The proportion of the visible surface area of a board that will yield clear pieces count. This is the surface measure (SM) and is calculated after measuring the length in feet and the width in inches. Multiplying the foot length by inch width and dividing by 12 gives the square feet SM. Measurements usually favour the buyer: a board measuring 8’ 7” long by 6-1/4” wide is tallied as 8 ft, by 6 ins = 4 square feet. Tallying convention when measuring random widths is to round up or down to the nearest 1/2”, eg, 6-1/4” wide and 6-3/4” wide are counted as 6” and 7” respectively. If board widths consistently measure on the half inch they are alternately noted up and down to the nearest inch.
Defects that count against a specific grading are: knots, both live knots or sound knots, and dead knots or unsound knots; severe surface checking, end splitting, and bark inclusions or pockets; sticker stain, bird peck damage, waney edge, worm holes, grub holes greater than 1/4” wide, and pith.
The following characteristics are permitted: mineral streaks as seen in poplar for example, and glassworm which looks like a random thread of broken grain pattern usually up to 6 mm (1/4”) wide and most commonly seen in ash; gum pockets or streaks frequently seen in cherry are not a fault, and nor are sticker marks which show as shadows as opposed to sticker stain; swirls or twists in the grain are permitted as is both heartwood and sapwood. The rules for heartwood and sapwood varies from species to species. Sapwood in cherry is considered undesirable as it detracts from the brown heartwood most buyers seek, whereas in ash and maple it’s considered desirable as it’s white. It’s not unusual in my experience to find American black cherry or black walnut boards where one side shows nearly all heartwood and the other is almost completely white sapwood. It’s annoying from my point of view as a maker because sometimes the heartwood side is very thin. By the time the piece is trued up large patches of the sapwood show on the best face. However this is the way the American grading system works and it’s necessary to allow for this when pricing projects and buying the wood.
The grades from best to worst are as follows:
• FAS (First and Seconds)
• FAS One Face (F1F)
• Selects
• Number 1 Common (No.1C)
• Number 2A Common (No.2AC)
• Number 2B Common (No. 2BC)
• Number 3A Common (No. 3AC)
• Number 3B Common (No. 3BC)
The following two grades are used primarily for the export market and as such don’t properly fit within the standard NHLA (National Hardwood Lumber Association) grading system.
• Prime Grade
• Comsel grade
Below the Number 2 Common grades the wood has quite a few faults and usually goes to make lower grade products such as pallets and packing cases so I shan’t describe it.
The following reference provides further guidance on the American grading system:
American Hardwood Export Council, (2006) The Illustrated Guide to American Hardwood Lumber Grades. [Online] Available at:
http://www.pals4wood.com/Documents/Illu ... gGuide.pdf [Accessed, November 23, 2007]
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