American lessons7 February 2009
In the fourth of his occasional series, the American Hardwood Export Council’s grading consultant Bob Sabistina answers some frequently-asked US hardwood grading questions
• The US National Hardwood Lumber Association grades are based on the percentage of clear, defect-free wood on a board.
• A number of American Hardwood Export Council members are doing special sorting for widths and lengths.
• The Selects grade is primarily applied to Northern US and Canadian species.
Question: We recently received a shipment of No. 1 Common white oak and there seemed to be quite a few pieces where the edges were not square and the ends were not trimmed very well. What is the ruling regarding this type of lumber?
Answer: The grading rules for North American hardwood lumber fall under the guidelines established long ago by the National Hardwood Lumber Association (NHLA, www.natlhardwood.org). The NHLA grades are based on the percentage of clear, defect-free wood available on the board. The No. 1 Common grade is required to yield a minimum of 662/3% clear, defect-free wood on the poor face of the board. Outside of this clear percentage, only the structural centre of the log (pith) is considered in determining the grade.
What you describe sounds like wane, which is defined as bark or lack of wood. Wane is limited in the upper grades (Selects, FAS1Face, and FAS) but not limited in the Common grades. The thinking is that the Common grades are designed to yield a limited number of shorter clear cuttings or pieces when the lumber is re-sawn in the manufacturing process. An edge or end that has wane is calculated in the measurement of the board but not included in its yield. Paragraph 8 in the NHLA Rule Book talks about lumber production: “It [lumber] should be edged and trimmed carefully to produce the best possible appearance while conserving the useable product of the log. If the supplier trimmed all the Common lumber to simply produce the best possible appearance, his yield would suffer which, in turn, would have a direct influence on the price. Most importantly is that the Common grades yield the buyer 662/3% and better clear area when run through the manufacturing process.”
Q: I am always forced to buy random widths and lengths from American suppliers. Can I purchase fixed widths and lengths?
A: Yes, a number of members of The American Hardwood Export Council (AHEC, www.ahec-europe.org) are doing special sorting for widths and lengths. The thing you must keep in mind is that a premium will be added to the price for this service, so study your yields and waste factors through your factory to decide if it is worth the premium.
It is worth mentioning that special sorts can also be made for colour. Other than for hard maple, which has several colour sorts, which relate to the sapwood content, the NHLA rules do not address sapwood or heartwood colour sorts. However, many suppliers offer colour sorting in cherry, tulipwood, ash, even red oak. Working closely with your supplier, making sure you have a good understanding of regional differences and having a working knowledge of the hard maple sorts should allow you to specify sapwood or heartwood content that is workable for you and your supplier.
Q: Please explain the difference between the FAS1Face and Selects grades.
A: The difference between these two upper grades is the required minimum size board. For FAS1Face (F1F), the required minimum size board must be the same as for FAS, for whatever species you are grading. For the most part this is a 6in-wide and 8ft-long board. There are a few exceptions to this requirement which would also apply to the F1F grade. For example, FAS white hard maple needs to have a minimum size board of 4in wide and 8ft long, which means that F1F white hard maple would also need to be 4in wide and 8ft long. To meet the Selects grade, the requirement is a minimum size of 4in wide and 6ft long. Other than this minimum size, the grades are the same. Both need to yield FAS on the better face and not below No. 1 Common on the poor side.
Historically, the Selects grade has been primarily applied to the northern US and Canadian species. These regions of North America have shorter growing seasons than the rest of the country and generally produce slower growth, smaller diameter timber. As you move through the midwest and Appalachian regions and, certainly, the southern regions of the US, you are more likely to see the F1F grade being used.
Q: Where can I get more information regarding the American grading rules?
A: AHEC has offices in Shanghai, Hong Kong, London, Osaka, Japan, Mexico City and Washington DC. It holds grading workshops throughout the year which range from a couple of hours to several days. It also distributes free publications on species, products, lumber grading, structural properties and architectural references.
The NHLA also holds an intense 14-week programme, twice a year in Memphis, Tennessee. Visit the NHLA website for more information.
Bob Sabistina worked with the NHLA for over 22 years as a field inspector. If you have a question for upcoming articles, email firstname.lastname@example.org.