Wood Utilization

Historical Perspective

I. From early 17th to early 20th century, wood was most valuable  
   raw material in America
     A. Abundant and ubiquitous
     B. Many uses were found for it

II. Early 20th century, shipbuilding, petroleum refining, and     
    automobile manufacturing became major USA industries
     A. Resulted in steady decrease in relative importance of
     timber products throughout this century (Fig 1.1)
     B. Wood still accounts for 1/4 of all industrial raw materials
     in USA (Fig 1.1)
     C. Timber based activity accounts for 4.1 % of gross national
     product, employing 3.3 million people

III. From 1840 - 1910 there was an expontial increase in timber   
     harvest, which declined during world war years, then returned 
     to a +- stable rate of 35 billion board feet per year (Fig   
     6.4)
     A. Current rate of harvest translates to 250 board feet per
     person per year (Fig 6.4)
     B. 1 Board Foot = 1' X 1' X 1" volume of wood

IV. Ways in which people use wood has changed during this century
     (Fig 14.8)
     A. Dramatice decrease in use as a Fuel until 1950, now +-
     stable at 20 ft^3 per capita
          1. Substitutes were found (Fig 10.2)
               a. < 1850 Coal
               b. 1855 Oil
               c. 1885 Gas
               e. 1890 Hydroelectic
               f. 1920 Natural Gas
     B. Sharp decrease in use as Lumber until 1940, increased
     during World War II years, slowly decreasing thereafter,
     now at 30 ft^3 per capita
          1. Substitutes were found for use in construction,
          transportation (automobile parts), & utensils (toys,
          cooperage, excelsior)
               a. Brick
               b. Concrete
               c. Steel
               d. Aluminum
               e. Plastic
     C. Steady increase in use as Pulp and Plywood (& other      
     composite lumber products)
          1. On percentage basis use of wood as pulp has
          become increasingly important since 1900 (Fig 10.1)
          2. Plywood and veneers began assuming importance 
          around 1940's (Fig 10.1)
          3. More efficient use of smaller trees
          4. USA began exporting logs to foreign nations         
          (primarily Asian) around 1960.(Fig 10.1)
          
V.  The areas within the USA from which timber harvest has been or 
    is important have shifted during this century (Fig 7.5)
     A. Lake States region (a) peaked in 1885
     B. Central region (e) peaked around 1900
     C. Southern region (b) peaked between 1910-1930, now second
     most important harvest area
     D. Western region (c) is now most important harvest area
     E. New England area (d) has always been +- constant low 
     harvest area


Categories of Wood Uses

"Wood is a renewable resource and indispensible to civilization"

" Wood is the most widely used commodity in the world save food &
     clothing"

I. Lumber Products
     
II. Wood Pulp Products

III. Fuel
     A. 1 Cord of Wood = 4' X 4' X 8' = 500 Board Feet
          NB.: 1 Cord of split wood < 1 cord of unsplit wood
               because of extra spaces between pieces
     B. In many of regions of world, fuel wood is now in very
          short supply

IV. Wood Tannins
     A. Extracted from wood & bark, used in rendering animal skins
     into useful leather.
     B. Primarily Tsuga, Quercus bark (Castanea wood R.I.P.) 
     C. USA now imports tropical barks and Myrobalan nuts

V. Wood Distillation Industry
     A. Navel Stores (from resinous exudate of Pinaceae sp)
          1. Turpentine for paints, varnishes, chemicals, medicine
          2. Rosin for glue, varnishes, soap, soldering,
          manufacture of sealing wax.
          3. Long leaf southern pines, introduced Norway Spruce
     B. Other Products
          1. Methanol (industrial solvent for polymers, mnfg of
          cholesterol, streptomycin, vitamins, hormones, other
          pharmaceuticals, organic & inorganic acids; antifreeze;
          octane booster for gasoline; fuel for picnic stoves &
          soldering torches; extractant for animal and vegetable
          oils; softening agent for pyroxylin plastics), & ethanol

          2. Acetone (Sovent for fats, oils, waxes, resins, rubber,
          plastics lacquers, varnishes, rubber cements; manfg of
          methyl isobutly ketone, mesityl oxide, acetic acid,
          diacetone alcohol, chloroform, iodoform, bromoform,
          explosives, aeroplane dopes, rayon, photographic films
          isoprene ; extraction of various principles from animal
          and plant substances; in paint and varnish removers;
          purifying paraffin; hardening and dehydrating tissues)

          3. Formaldehyde (Disinfecting swellings, ships, storage
          houses, utensils, clothes, etc.  Germicide & fungicide
          for plant; destroying flies & other insects. Manfg
          phenolic resins, artificail silk and cellulose esters,
          dyes, organic chemicals, glass mirrors, explosives,
          improving fastness of dyes on fabrics, tanning and
          preserving hides, mordanting and waterproofing fabvrics,
          preserving and coagulating rubber latex, in embalming
          fluids.  Prevents mildew and spelt in wheat & rot in
          oats, to render casein, albumin and geletin, and in
          chemical analyses)

          4. Pyroligneous acid "liquid smoke"

          5. Calcium Acetate (mnfg. acetic acid, acetone, used in
          dyeing, tanning, curing animal skins, in lubricants, as
          food stabilizer, corrosion inhibitor)

          6. Wood creosote (antiseptic, expectorant, veternary use
          [except cats] antiseptic, parsiticide, deodorant,
          expectorand, gastric sedative, gastorintestinal
          antiseptic)
          
          7. Tar Oil (topical antiseptic, dermatologic veternary
          use anticeptic, antipruritic, chronic skin conditions &
          hoof dressings, expectorant)
          
          8. Charcoal

     C. Sources of other products

          1. North -> Fagus, Betula, Acer
          2. South -> Yellow Pines
          3. Northwest -> Pseudotsuga

Anatomical Bases for Economically Important Wood Properties

I. Density (Weight per Volume) depends upon:
     A. Thickness of cell walls of wood elements
     B. Presence of secondary compounds in cell walls
     C. Presence of water (12% moisture content is industrial
     standard)

II. Specific Gravity
     A. (Weight of oven-dry wood at 100 C)/62.4 lbs
          [weight of similar volume of water]
     B. Guaiacum sp. (Lignumvitae) [Zygophyllaceae, Caltrop Family]
     of C. America is one of the heaviest woods known
          1. 78 lbs/ ft^3, Specific gravity = 1.25!
          2. gum resin makes this wood self lubricating
     C. Ochroma lagopus (Balsa) [Bombacaceae] is one of the
     lightest woods known
          1. 7-10 lbs/ft^3, Specific gravity = 0.112-0.162
          2. Very fast growing

III. Texture
     A. Size and quality of wood elements
     B. Conifers
          1. Tangential diameter of tracheids
     C. Angiosperms
          1. Tangential diameter of vessels
          2. Size and number of rays per unit volume

IV. Strength
     A. In general proporational to density
     B. Rate of tree growth also influences
     C. In conifers
          1. more summer wood -> stronger
          2. In general, the amount of spring wood varies with ring
          width, but amount of summer wood is +- constant   
          3. Therefore, slower growth -> stronger wood
     D. In Ring Porous Angiosperms
          1. More summer wood -> stronger
          2. In general, the amount of spring wood does not vary
          with ring width, but amount of summer wood does
          3. Therefore, faster growth -> stronger
     E. Diffuse Porous Angiosperms
          1. Strength +- independent of growth