Tsuga candensis

 

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Family: Pinaceae

 

 

 

 

 

 

 

 

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Eastern Hemlock

 

 

 

The genus Tsuga contains about 14 species native to North America [4] and southern and eastern Asia [10]. The word tsuga is the Japanese name for the native hemlocks of Japan. The word canadensis means "of Canada".

Other Common Names: Abete del Canada, American hemlock, black hemlock, Canadese hemlock, Canadese hemlock-den, Canadian hemlock, eastern hemlock, hemlock spruce, Huron pine, kanadensisk tsuga, New England hemlock, Pennsylvania hemlock, perusse, pine, pruche de l'est, pruche prusse, red hemlock, sapin du Canada, schierlingstanne, spruce, spruce hemlock, spruce pine, tsuga canadese, tsuga del Canada, tsuga du Canada, vanlig hemlock, water hemlock, water spruce, West Virginia hemlock, white hemlock, Wisconsin white hemlock.

Distribution: Eastern hemlock is native to Cape Breton Islands, Nova Scotia, Prince Edward Island, New Brunswick, the Gaspe’ Peninsula of southern Quebec and Maine, west to southern Ontario, northern Michigan, Wisconsin, and eastern Minnesota, south to Indiana and east to Ohio, Pennsylvania, Maryland and New Jersey and south in the mountains to northwestern South Carolina, northern Georgia and northern Alabama. The production of hemlock lumber is divided fairly evenly between the New England States, the Middle Atlantic States, and the Lake States.

The Tree: Mature eastern Hemlock trees commonly reach heights of 100 feet, with diameters of 3 feet. A record tree was recorded at 160 feet, 7 foot diameter and an age of 988 years.

General Wood Characteristics: The heartwood of eastern hemlock is pale brown with a reddish hue. The sapwood is not distinctly separated from the heartwood but may be lighter in color. The wood is coarse and uneven in texture (old trees tend to have considerable shake); it is moderately light in weight, moderately hard, moderately low in strength, moderately limber, and moderately low in shock resistance.

 

 

 

Mechanical Properties (2-inch standard)

 

 

 

 

Compression

 

 

 

 

Specific

gravity

MOE

x106 lbf/in2

MOR

lbf/in2

Parallel

lbf/in2

Perpendicular

lbf/in2

WMLa

in-lbf/in3

Hardness

lbf

Shear

lbf/in2

Green

0.38

1.07

6400

3080

360

6.7

400

850

Dry

0.43

1.20

8900

5410

850

6.8

500

1060

aWML = Work to maximum load.

Reference (56).

 

Drying and Shrinkage

Type of shrinkage

Percentage of shrinkage
(green to final moisture content)

0% MC

6% MC

20% MC

Tangential

6.8

5.4

2.3

Radial

3.0

2.4

1.0

Volumetric

9.7

7.8

3.2

References: (56, 192).

Kiln Drying Schedulesa

 

Conventional temperature/moisture content-controlled schedulesa


Condition

4/4, 5/4
stock

6/4 stock

8/4
stock

10/4
stock

12/4
stock

British schedule
4/4 stock

Standard

T12-C4

NA

T11-C3

T8-A3

T8-A2

K

 

 

 

 

 

 

 

aReference (28, 185).

Working Properties: Eastern hemlock splinters easily when worked with tools. It is low in splitting resistance and average in nail holding capacity. It also glues easily and is moderate in paint holding ability.

Durability: Eastern hemlock is rated as slightly or nonresistant to heartwood decay (11).

Preservation: It is rated as resistant to preservative treatment (7).

Uses: Eastern hemlock is used principally for lumber and pulpwood. The lumber is used largely in building construction for framing, sheathing, subflooring, and roof boards, and in the manufacture of boxes, pallets, and crates.

Toxicity: Working with eastern hemlock may cause dermatitis (6&8).

Additional Reading and References Cited (in parentheses)

1. Boone, R. S.; Kozlik, C. J.; Bois, P. J., and Wengert, E. M. Dry kiln schedules for commercial woods - temperate and tropical. Madison, WI: USDA Forest Service, FPL-GTR-57; 1988.

2. Brisbin, R. L. Eastern hemlock [Tsuga canadensis (L.) Carr.]. Washington, DC, USA: USDA Forest Service, FS-239; 1970.

3. Dallimore, W.; Jackson, A. B., and Harrison, S. G. A handbook of Coniferae and Ginkgoaceae. London, UK: Edward Arnold Ltd.; 1966.

4. Elias, T. S. The complete trees of North America, field guide and natural history. New York, NY: van Nostrand Reinhold Co.; 1980.

5. Godman, R. M. and Lancaster, K. Tsuga canadensis (L.) Carr. in: Burns, R. M. and Honkala, B. H., tech. coords. Silvics of North America. Volume 1, Conifers. Washington, DC: USDA Forest Service; 1990; pp. 604-612.

6. Hausen, B. M. Woods injurious to human health. A manual. New York, NY: Walter de Gruyter; 1981.

7. Henderson, F. Y. A handbook of softwoods. London: HMSO; 1977.

8. Mitchell, J. and Rook, A. Botanical dermatology: plants and plant products injurious to the skin. Vancouver, BC: Greenglass

Ltd.; 1979.

9. Simpson, W. T. Dry kiln operator's manual. Madison, WI: USDA Forest Service, FPL Ag. Handbook No. 188; 1991.

10. Summitt, R. and Sliker, A. CRC handbook of materials science. Vol. 4. Boca Raton, FL: CRC Press, Inc.; 1980.

11. USDA. Wood handbook: wood as an engineering material. Madison, WI: USDA Forest Service, FPL Ag. Handbook No. 72; 1974.