Softwood
Description
One of two common classifications for trees, Hardwood (angiosperm) and softwood (gymnosperm). Softwoods are coniferous trees. With the exception of the larch and cypress trees, softwoods do not shed their needle-like leaves. Examples of softwood trees are: Pine, Fir, Hemlock, Spruce, Tamarack, Cedar, and Redwood. Softwood trees are found in temperate and mountainous regions. Most of softwoods are used for general construction, fences, and paper pulp. Softwood trees tend to have less acetic acid (1-2%) than hardwoods (3-5%) (Hatchfield 2002).
Synonyms and Related Terms
nanboku (Jap.); bois tendre (Fr.); legno di conifera (It.); evergreen; coniferous
Physical and Chemical Properties
Contain tracheids rather than pores. May contain resin channels.
Paper fiber type: Softwood. Using transmitted light microscopy, softwood fibers are identified by the presence of intertrachied "bordered" pits and species specific features such as ray parenchyma pits, size, width, etc. Appearance with Graff "C" stain: sulfite= warm pink to grey, appearance gets lighter with progressive bleaching, kraft=grey blue to purple, appearance gets lighter with progressive bleaching. Average dimensions of fibers: species dependent (average= 3-3.6mm). Common pulping method: kraft and sulfite. The long fibers of softwood pulp impart strength to paper and are often used in conjunction with Hardwood and Rag pulps. Softwood can be pulped mechanically or chemically.
Additional Images
Softwood bleached sulfite paper pulp stained with Graff "C" stain
Softwood unbleached kraft paper pulp stained with Graff "C" stain
Softwood groundwood paper pulp stained with Graff "C" stain
Softwood bleached alpha paper pulp stained with Graff "C" stain
Example of pitting in softwood fibers stained with Graff "C" stain
Red pine paper pulp stained with Graff "C" stain
Sugar paper pulp stained with Graff "C" stain
Larch paper pulp stained with Graff "C" stain
Douglas fir paper pulp stained with Graff "C" stain
Spruce paper pulp stained with Graff "C" stain
Resources and Citations
- Alden Identification Services, Microscopic Wood Identification: Link
- G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 875
- Ralph Mayer, A Dictionary of Art Terms and Techniques, Harper and Row Publishers, New York, 1969 (also 1945 printing)
- Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993
- Pam Hatchfield, Pollutants in the Museum Environment, Archetype Press, London, 2002
- AMOL reCollections Glossary -http://amol.org.au/recollections/7/c/
- Museum of Japanese Traditional Art Crafts at http://www.nihon-kogeikai.com/ (Jap. term)
- Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997
- Marja-Sisko Ilvessalo-Pfäffli. Fiber Atlas: Identification of Papermaking Fibers (Springer Series in Wood Science). Springer, 1995.
- Walter Rantanen. "Fiber ID Course." Integrated Paper Services. June 2013. Lecture.