Grading Options for Western Hemlock "Pulpwood" Logs from Southeastern Alaska

Issue:
In southeastern Alaska, large high quality logs of western hemlock (Tsuga heterophylla) have traditionally been cut into export cants and lower quality logs have generally been chipped for pulp. While pulp chips may still be exported, the demise of local pulping facilities has all but eliminated markets for these lower quality logs. Although product recovery studies were conducted in the 1970s and 1980s, these studies did not focus on the grading systems currently used for engineered wood products, such as wooden trusses, I-joists, and glued-laminated timbers.

Objective:
The objective of this study is to estimate the grade yield of structural dimension lumber that can be obtained from lower quality western hemlock "pulp logs."

Cooperators:
The primary cooperators in this study were the US Forest Service, Marketing Unit, State and Private Forestry, Madison, WI; Pacific Northwest Research Station, Sitka, AK; Viking Lumber Co., Klawock, AK., Western Wood Products Association, Portand, OR.

Approach:
Four hundred and nine logs were selected at random from inventory at a mill in southeastern Alaska. The Puget Sound Log Scaling and Grading Bureau graded the majority of the logs (89%) as either No. 3 or No. 4, 4% graded as No.2, and 7% as "cul'' logs. The culls could not be processed in a commercial sawmill. Small-end diameter of the 32-ft-long logs ranged from 5 to 36 inches, with most less than 12 inches in diameter. The logs were sawn into nominal 2x4, 2x6, and 2x10 lumber and visually graded as structural lumber by a WWPA Quality Supervisor. All lumber that graded at least No.3 Structural Framing in the rough, green condition was dried, surfaced, and shipped to the Forest Products Laboratory for testing.

Results:
For dried and planed lumber, approximately 50% of the lumber graded as No.2 and better and 67% as No.3 and better. No. 2 and better lumber is particularly suited for framing and truss production, and No. 3 for general construction. In the lower 48 states, about 80% of Machine Stress Rated (MSR) lumber is used in truss production and 20% as flange material for wooden I-joists. About 9% of the 2x4's could qualify as 2400f-2.0E MSR (allowable properties for Select Structural are only 2100f-1.6E) and about 42% as 1450f-1.3E (about the same strength as No.1). When graded as lamstock for glued-laminated timbers approximately 28% made the highest (L1) grade and 61 percent qualified for all grades. Over 85% of the L1 and L2 grades qualified as "Dense".

Yield of All Widths Based on Dried and Planed Lumber
Structural Framing Lamstock

Grade	Yield	Grade	Yield
Sel. Str.	14.1%	L1	28.5
No.1	13.6	L2	16.8
No.2	23.0	L3	16.6
No.3	17.3	<L3	38.1
< No.3	32.0

Implications:
The results of this research demonstrate that a significant amount of high quality structural lumber can be produced from Alaskan hemlock logs once used primarily for production of pulp chips. This does not imply that a modern production-oriented mill would be established just to process such logs. Rather, this study indicates that it may be worth considering processing such logs into lumber instead sending these logs to the chipper. This research did not evaluate potential markets for hemlock or address economic feasibility. The research also did not evaluate the yield of structural lumber from higher quality "sawlogs". The next steps for any Alaskan mills interested in producing structural lumber are as follows:

• Investigate potential markets and market requirements for specific types of lumber products.
• Conduct a yield study at the mill, for products of interest, using locally available logs.
• Evaluate the economic feasibility of producing these specific lumber products.
• Arrange certification by a grading agency certified by American Lumber Standards Committee.

As is generally true with all grading systems, markets are more easily found for the higher grade lumber. The challenge is to find markets for the 45% to 60% of the wood that did not make the lowest lumber grades.

Information:
Green, D.W.; McDonald, K.A.; Dramm, J.A.; Kilborn, K. 1999. Grading options for western hemlock "pulpwood" logs from southeastern Alaska. Research Paper FPL-RP-583. US Forest Service, Forest Products Laboratory, Madison, WI. (http://www.fpl.fs.fed.us/).