Summary
• The grading rules for walnut are unique.
• Walnut lumber is steamed before sale.
• Steaming darkens the sapwood to the colour of the heartwood.
• The NHLA grades for walnut are FAS, FAS1Face, Selects, No. 1 Common and No. 2A Common.

Question: What is steamed walnut?
Answer: The first process in preparing walnut lumber for sale is to steam the fresh-sawn boards. Steaming darkens the normally cream-coloured sapwood, allowing it to blend more readily with the chocolate heartwood in the finishing process. For best results, steaming should be done as the lumber is sawn and the moisture content is at its highest. The lumber should be flat-piled and the sapwood should be in contact with the heartwood of each board. The stacks are placed in a steamer, similar to a smokehouse, for several days. Once steamed, the sapwood is no longer considered in the grading rules, and the lumber is placed on stickers for kiln-drying.

The NHLA grades for walnut are FAS, FAS1Face, Selects, No. 1 Common, and No. 2A Common, similar to the Standard grades for other hardwood species. FAS walnut combines the current clear-face cutting method of grading with the former method of defect grading.

Q: My supplier says that FAS walnut is graded by counting defects. What does this mean?
A: Instead of calculating the percentage of clear wood on the board, the inspector counts defects. The width will determine the number of defects allowed. In FAS walnut, the defect method applies to boards 6ft and 7ft long and the clear-cutting method applies to boards 8ft and longer.

FAS walnut will allow boards of a minimum 5inwidth. For 6ft and 7ft boards to qualify for FAS, the grader counts the number of defects, ie knots, wane, splits. Boards of 5, 6, and 7in width will allow one Standard Defect and boards 8in and wider will allow two Standard Defects. In addition, a small amount of wane is permitted, along with up to 6in of split on the ends.

Q: What is a Standard Defect?
A: For a full description see pp28-30 of the 2007 NHLA Rules book. The following sums up the minimum requirements and the most common defects allowed:

FAS walnut 6ft & 7ft – graded on the Defect Method
• minimum width = 5in;
• boards 5in, 6in, & 7in wide allow one Standard Defect;
• boards 8in and wider admit two Standard Defects;
• also allows: 6in split; 12in of wane in 6ft boards; 14in of wane in 7ft boards.

One Standard Defect includes:
• one knot with average diameter not over 11/4in;
• two knots when added together not over 11/4in;
• wane not over 12in in 6ft boards; 14in in 7ft boards;
• split equal to the surface measure in inches.

Q: When we receive FAS walnut of 8ft and longer, there are smaller clear cuttings. Are these allowed?
A: FAS walnut 8ft and longer, and all the other walnut grades, are based on the clear-cutting grading method on which all NHLA grades are based. Because of the high demand for walnut, the Standard grades have been altered to allow more volume to be available.

FAS walnut 8ft and longer is graded as Standard, except that widths are 5in and wider. The minimum clear cuttings are 4in wide by 3ft long or 3in wide by 6ft long. Boards with a surface measure of 3-7ft allow two clear cuttings; boards with an 8ft surface measure or more will allow three clear cuttings. All other FAS Standards apply.

FAS1Face walnut and Selects have two ways to meet the grade. The first is that they must meet the same criteria as the Standard grades, ie both must grade FAS walnut on the better face and No. 1 Com walnut on the poor face. There is no wane limitation on the No. 1 Com face. The second is that these grades will also allow a “sound back”, ie if you grade FAS on the good face and the reverse side of the FAS cuttings are structurally sound, the board will also qualify for FAS1Face or Selects.

Q: Are there any differences in the grading rules for No. 1 Common walnut?
A: No. 1 Common walnut is graded Standard except that unlimited clear cuttings are allowed.

Q: What about No. 2A Common walnut?
A: It is graded Standard except that unlimited clear cuttings are allowed, as well as minimum cutting size of 2in and wider containing six cutting units.