Limba (afara, fraké, korina)

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Title:
Limba (afara, fraké, korina)
Physical Description:
Unknown
Creator:
Gerry, Eloise
Forest Products Laboratory (U.S.)
Publisher:
U.S. Dept. of Agriculture, Forest Service, Forest Products Laboratory ( Madison, Wis )
Publication Date:

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All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 29320689
oclc - 244006036
System ID:
AA00020592:00001

Full Text


I~ ~


Forest Products Laboratory,' Forest Service
U. S. Department of Agriculture
1950 u.s: "
..h A


LIIMBA 2 -
(Afara, FrakS, Korina-.) AT-LAN-."
Terminalia superba Engl. et Diels 4TLNA T


.'amily: uomoretaceae -r, .
.S -- E, EP-'


By
U.S. DEPOS' -.--'Y
ELOISB GERRY, Forest Products Technologist.- -,--
Division of Silvicultural Relations



Terminalia superba Engl. et Diels is a West African species which is
known by various common names. The specific name superba suggests
the handsome appearance of the tree which is widely distributed from
French Guinea to the Oameroons, the Belgian Congo and Angola (15, 19).
It prefers the humid forests without a dry season. The name Terminalia
refers to the leaves, which occur in tufts at the ends of the branches (l9).

Some of the common or trade names are (15):


White afara


(United Kingdom and Nigeria)


Limba clair or light lima (Belgium, Belgian Congo and Angola)
Limba noir or dark limba- (


Limbo
Ohene limbo
Frakd
Noyer du Mayombe
Ofram Gold Coast
Kori na


( )
France and French West Africa)
( )


'Maintained at Madison, Wis., in cooperation with the University of
Wisconsin.
2Trademarked name. (See Veneers and Plywood 43(3):26-27, Mar, 1949.
3Underlined numbers in parentheses refer to the list of numbered references
at the end of this leaflet.
Black or dark afara is a name generally applied to Idigbo (Terminalia
ivorensis) because of its dark bark, its wood being pale yellow (5).


Agriculture-Madison


) j ~1
'I


INFORMATION LEAFLET
FOREIGN WOODS


ii ii J[ 1 Jl I I II I I I i I I


..... i III iii i ii i


Report No. R1779






THE TREO

Limba grows rapidly but is not very long lived (19). It may attain
a height of 150 feet or more and usually has an extremely straight
clear, cylindrical stem, with a buttressed base which often extends
8 feet or more above the ground. Diameters, above the buttresses,
may range from 3 to 5 feet. The tree may occur in nearly pure stands.

Branches are produced in whorls; the tops of the trees may be flattish.
The bark is ashy gray, scaly and fissured in older trees. Plantations
made in 7est Africa appear to be succeeding and yields from managed
forests are promising (6, 15, 19). At 20 years trees may have clean,
straight boles 50 to 60 feet in height with a girth of about 5 feet.
The trees coppice from stumps, are adaptable and reproduce naturally
(20). They prefer good light for best growth (heliophile) and tend
to be shallow rooted (5, D).

The numerous small yellowish or whitish green flowers are in simple,
axillary racemes. The fruits are abundant and in the form of samaras,
each about 3/4-inch long, with a lateral spread of wing of 1-1/2 to
2 inches (20).


THE WOOD


Color

Usually both heartwood and sapwood are light gray-white to pale creamy-
brown in color, similar to light oak. Sometimes, however, the heartwood
contains irregular grayish markings, with streaks that may be almost
black; this wood may bring an extra price. The cause of these markings
is not fully understood (D, 22). For some purposes, the varied dark
wood has been specially valued, and for others the light color is its
chief asset (4).

The name limba clair (or limba blanc) is given to logs in which about
two-thirds or more of the diameter is light in color, with heart color
less than 10 centimeters in diameter (19). Limba noir (limba-bariole,
or walnut of Mayombe) is the name applied to timbers in which the dark
heartwood is large enough to show on the sides of the squared logs (15, 19).
The name limbo demi-noir is given to irregularly veined material, with
color on two-thirds of the diameter of the log (19).

Weight f I

Limba is reported to weigh about 35 pounds per cubic foot at 15 percent
moisture content (15). Reports list specific gravity (oven dry weight aind
green volume) as o07. to 0.51 (6, ), optimum 0.50-0.60 (L9), green,
0.75 (l.-


Report No. R1778 -2-






Grain, Texture and Figure


Limba is rated as generally straight-grained, although wavy grain may
occur, producing a desired figure (1). The texture varies from close
to rather coarse but even (6).

Mechanical Properties

In large logs the heartwood may be brittle, and as a rule the dark colored
wood tends to be more brittle than the light.

Complete strength tests have not been carried out. but the timber rates as
not very strong, not as strong as oak (7, 15, 19). One plank from Nigeria
was tested in England (I) with the results given in the accompanying table.

A very small number of tests on a few boards were made at the U. S. Forest
Products Laboratory in 1948. Wood with specific gravities of 0.515 to
0.645 gave values corresponding roughly with those for black cherry, black
tupelo, red maple, and American elm.

Seasoning

Kiln drying is reported to be easily accomplished with little tendency
for the development of defects. A schedule about like that for ash
can be used-. The wood shows stability when manufactured. Care is
required if the wood is air seasoned to prevent decay and discoloration
(D). Shrinkage is reported to be rather small (D) but greater in the
dark colored portions.

Durability

Limba is not resistant to decay, insects, or termites (19) and the heart-
wood of large trees is frequently found to be unsound, or even hollow, when
felled (14). The sapwood stains readily in a manner similar to the bluing
of softwoods. Logs are attacked by pinhole borers in both sapwood and
heartwood. Powder-post beetles may attack sapwood (15). Preservative
treatments are reported to prevent damage by fungi and insects (6).

Working Characteristics

The timber has been found to work easily with hand and machine tools;
it turns well. If the grain is uneven it may "pick up" in planing, but
this is said to be overcome by using a low cutting angle (15). Limba
veneers without trouble. The wood finishes well when a filler is used.
It glues readily and does not "bleed" (5),but care is required in nailing
and screwing, for the wood has a tendency to split (15).

2Tests by the Forest Products Research Laboratories in England were made on
a related species, Terminalia ivorensis (Idigbo), and are published in
the periodical "Wood" (British) for July 1938 for purposes of comparison
with other Gold Coast woods.
6A suggested schedule would be similar to No. 3 given in Technical Note 175,
U. S. Forest Products Laboratory, Madison, Wis.


Report No. R177-


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Summary of Results of the Mechanical Tests on Afara Wood
(Terminalia sperba) from Nigeria (1)


A.--Transverse bending test (central loading):


Maximqm calculated longitudinal
shear ....... .......Lb./sq.
Modulus of rupture.............Lb./sq.
Fibre stress at elastic limit.Lb./sq.
Modulus of elasticity...'. .... .Lb./sq.
Elastic resilience.......Inch-lb./cu.


in.
in.
in.
in.
in.


B.--Compression test along the grain (24 in.
length specimen):
Crushing strength.............Lb./sq. in.
Fibre strength at elastic


limit......................... ... Lb./sq.
Modulus of elasticity.........Lb./sq.
Elastic resilience.......Inch-lb./cu.

C.--Compression test along the grain
(8 in. length specimen):
Crushing strength.............Lb./sq.
Fibre strength at elastic
limit... .... .. .. .. .. .. .... b isq.
Modulus of elasticity.........Lb./sq.
Elastic resilience....... Inch-lb./cu.


in.
in.
in.


in.

in.
in.
in.


4.,625
1,285,000
7-45


Maximum


367.5
10,230
7,850
1,345,00ooo
22.34



6,oo000

5,475
1,233,000
10 28


5,475
4,500
1,100,000
6.49


Minimum


187.5
5,225
4,139
1,192,000
0.679



5,260

4,125
1,213,000
5"94


5,738

4,567
1,198,000
6.87


D.--O Compression test across the grain:
Load at elastic limit.................Lb.
Fibre stress at elastic limit.Lb./sq. in.

E.--Shearing tests along the grain:
Radial--
Maximum load supported...... ........Lb.
Shearing strength...........Lb./sq. in.
Tangential--
Maximum load supported............. Lb.
Shearing strength...........Lb./sq. in.


Specific gravity......................... .
Weight per cubic foot...................Lb.
Moisture..... ..........................Percent


Report No. R1778


4,700
1,175



4,710
1,178

6,140
1,535


0-515
32.2
11-37


4,200
1,050



4,540
1,135

6,050
1,513


0o454
28.4
9*85


4,4oo
1,098



4.640
1,160

6,o100
1,525


0-486
30.4
10.29


Mean


286.5
7,9b8
.6.229
1,272,000
1.70



5,620

4,610
1,223,000
7"46







Uses

The use of limba is increasing. It is used as solid wood and also as
veneer and plywood, and is especially popular for blond furniture, school
and shop fittings, radio and television cabinets, parquetry, and
joinery. It has been used in construction but is too useful in other
fields at present to be so used (4_, 1_). Limba is said to have been
used in South Africa and in Germany for propellers and patterns, and has
been given preliminary tests for pulp making (16) where rather high
chemical consumption and dark stock were noted. However, this use is
considered possible in the future, for it has been found to yield
sufficiently strong kraft pulp (19).

Supplies

Supplies are normally abundant. The wood is imported in logs up to
30 inches in diameter or planks up to 30 inches wide and lengths up
to 20 feet (_, 1). Ports of export include Boma, Kouilou, Matadi, and
Landana.

Minute Structure

Growth rings are usually distinct and often conspicuous on the end
surface; they are usually undulating. The boundaries are marked by a
band of darker tissue at the end of the growth zone. Sometimes a narrow,
discontinuous band of soft tissue is present, visible under a magnifying
glass.

The pores are rather large, individually distinct to the naked eye.
They are very few to few in number and rather evenly distributed,
usually much smaller at the end of the growth ring. They tend to show
as oblique lines; although mostly solitary, occasionally they appear
in radial groups of 2, 3, or even 4. On longitudinal surfaces the pores
or vessels are conspicuous as deep scratches, occasionally sparkling.

Tyloses.--Bright, iridescent tyloses are sometimes abundant.

Parenchyma is moderately abundant, not very distinct to the naked eye.
It is discontinuous but borders the pores and extends laterally, often
linking them in wavy lines. Crystals are often present in the vertical
parenchyma (I).

ays are very fine, not visible to the naked eye and inconspicuous even
on radial surfaces. They are usually uniseriate (19).

Fiber length is reported as 1.20 millimeters (average), and diameter
27.5 microns (16).

Ash

Although rich in ash, the proportion of silica is small (19).


Report No. R1779


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List of References


1. Anon.
1923. Results of Examination of Nigerian Timbers-Afara
Bull. Imperial Institute 21(3):445-44g ,

2. ______________-_____
1928. Nos Bois Coloniaux: Limbo. Asso. Colonies Sciences et
Co1it4 National des Bois Coloniaux, 44I Rue Blanche Paris.
(See Record, Tropical Woods 18:26-28, Yale University, School of
Forestry, New Haven, Conn.)

35
1948. In California Lumber Merchant, May 1, p. 42 (U. S. Plywood
Importers)

4.
1949 From the Belgian Congo to the American Home ("Korina").
Wood Working Digest 51(5): 171, May. Illus.

5. Brush, W. D. and Sparhawk, W. N.
1943. West African Timbers for use in North America.
Unpublished material in U. S. Forest Service. files. U. S.
Department of Agriculture.

6. Chalk, L., Davy, J. B., Desch, H. B., and. Hoyle, A. C.
1933. Forest trees and timbers of the British Empire.
II. Twenty West African Timber Trees, pp. 30-35 (illus.)
Clarenden Press, Oxford, England (115 references).

7. Comitd National des Bois Tropicaux (16 Rue de la Paix, Paris, 2e)
1931 (a) No. 1. Etude physique et m4canique des Bois Coloniaux.
152 pp.
1933 (b) Premier complement. 25 pp.
1944 (c) Deuxikme complement.

8. ___^______________________
1949. Nos Bois Tropicaux Limbo. pp. 22-23.

9.
1949. Limbo. Bois et Forets des Tropiques No. 9 l1er Trimestre,
pp. 63-66.

10. Cooper, G. P. and Record, S. J.
1931. The Evergreen Forests of Liberia. Yale University,
School of Forestry, New Haven, Conn. Bull. No. 31.
11. Duchesne, Fl.
1947. La Section Economique der Musie du Congo Beige.
Annales du Musee du Congo Beige Tervuren Series in 8.
Sciences, Historiques et Economiques Vol. 1, pp. 161-162,
Oct. Illus.


Report No. R1778


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12. Hedin, L.
1929. Sur quelques essences forestidres exploit4es au
Cameroun. Rev. Bot. Appl. et d Agr. Tropicale 9:99:39-51
Jan. Paris (Tropical Woods 20 pp. 43-50).

13. Hutchison and Dalziel, J. M.
1927-1931. Flora of West Tropical Africa. Vol. 1, pt. 1, p. 226
(See Trop. Woods 18:27, 1929. T. superba Engl. et Diels =
T. altissima Chev.) See (5).

14. Irvine, F. R.
1930. Plants of the Gold Coast. Oxford.

15. Jay, B. Alwyn
1950. Timbers of West Africa, 3rd ed., pp. 8-10,
Timber Development Asso. Ltd., 75 Cannon St., London E.C. 4.

16. LeOacheux, Paul
1946. L'Utilizatidn des Essences Tropicales dans L1Industrie
des Pates et Papiers. pp. 151-156 (Fiber lengths).

17. Meniaud, J.
1931. Nos Bois Coloniaux. Paris.

18. Meyer, Hans
1933. Book of Wood Names (Buch der Holznamen) N.& H. Schafer,
Hannover, Germany.

19. Normand, D.
1947. Le Limbo (Frakd) Revue du Bois 2(5): 3-6. Illus. May.
(Transl. by E. Gerry)

20. Record, S. J.
1929. Walnut Woods -- True and False. (Noyer du Mayombe or Congo
walnut) Tropical Woods 18:4-29 (26-28).

21. Record, S. J. and Hess, R. W.
1943. Timbers of the New World. p. 130, Yale University Press,
New Haven, Conn.

22. Scott, M. H.
1943. Some West African Substitutes for Well-Known Timbers.
Jour. South African Forestry Assoc. No. 10:29-39, April.

23. Stone, H. and Cox, H. A.
1922. Timbers of Nigeria. Crown Agents for the Colonies, London.

24. Unwin, A. H.
1930. West African Forests and Forestry. London.


Report No. R1778


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