Sen

I-


F O R E I G N eW O e D S E R I E S _


SIEN



No. 1979


revised January 1957


"TMADISON~~I C ICNI cooperation with the Univervity of Wisconsin


1













; :,. ....._ p i ctud ( .'! !.. ,) *', "
Fai ly: ,,',a",1 iac'ae



i'. F. KUKAY'.K.4, A, Forest t iit I ]slt
Forest *' I ictB IIborat r.. Forest sxrv1ce
U,,. ..jpartnmeknt f P,' ult ur'






Introduction

Soen, which is also known as hri-:'i-:, Castor Arabia, int more recently under
the c<:[-.'ri,-,.t, i name "nakora," is a J'nrirn- se hardwood belr,-inj to the
gins. ni -'n.iy. Sen occurs most commonly in the temperate-zone, mountainous
forests in the northern part of Honshu and in all 'Lrts _'. Hokkaido. In
deep forests or on fertile ground, the trees imay -row to exceptionally larr"..
sizes, but they more cr'nm.,ni- attain hel-j:ts of 80 feet anr diameters ', to
4o inches. Althou-h sen makes up a relatively .m..ll volume of the total
Japanese hardwood production, it is considered one of the more im. r-ri.-t
species. This -i.pcies is sometimes sold as Japirn F.. ash, but the name is
inappropriate because ash bel'.nrr-.; to the :-..'140 .ri: iinus of the family
l0. iroae. References to this sr-.cies may also be found in the literature
under the synonyrr:; A-ant }:. ;.'rix': ric i n: 'olium "n m. and Kalopanax ricinifolium
Miq. Although Kalopanax pictus also occurs in China, Manchuria, ir. i Korea,
it is imported to the United States only from .Trj u.


TL. Wood


The sapwood -f s',n is white, a,] the heartwood -ui;. be a -..'illowish brown
to a grayish brown. Tm.'-.,re is no sharp line of demarcation between s-:.:d
and heartwood. The fi.ur,, [r'.luced "*.' the lar7-- :".,r-w ; -re zone S---
gests ash (FIraxinu3s spp.) when flat sa:n or rotary cut and American elm
(Ulmus americana L.) in ,.;-iartered material. T,.:' wood is a* "-!..t **-.-." n.,
lustrous, and similar to -a.h ",n,: American elm in texture.




maintained at Madison, Wis., in cooperation with the universityy "
Wisconsin.



Rept. No. 1979 (Revised) -1- A.rriculture-Madic:n









Mechanical Properties


Sen is lighter in weight than either American elm or commercial white ash.
At 12 percent moisture content, sen weighs about 28 pounds per cubic foot,
American elm about 31 pounds, and ash about 36 pounds. Elm and ash both
exceed sen in all strength properties as shown in table 1. On the basis of
atrvngth properties, sen is more nearly comparable to red alder (Alnus rubra
Bong.), American chestnut (Castanea dentata (Marsh.) Borkh.), and yellow-
pFoplar (Liriodendron tulipifera L.).


Seasoning and Shrinkage

Sen reportedly shrinks and swells appreciably with changes in moisture
content. However, no values are available regarding this property. The wood
can be air-seasoned or kiln-dried without difficulty.a


Workability

Sen is rated as being easy to work.2


Finishing

The coarse texture of the springwood pore zone necessitates the use of fillers
when a smooth, continuous finish is required.


Durability

Sen is nondurable and therefore best suited for interior use.


Uses

In Japan, sen is used in general construction and the manufacture of cabinets,
furniture, interior trim, carved items, chests, handles, plywood, musical
instruments, boats, and numerous miscellaneous articles.

In the United States, it is used primarily in the form of plywood for paneling
and doors.


Rept. No. 1979


ZBruce, H. D., Cockrell, R. A., and Cummings, L. J. Properties and Uses of
Commercially Important Japanese Woods. Natural Resources Section, General
Headquarters, SCAP, Report No. 147, October 1951.


-2-











u Ij; !-.1n an,] r,. ,'r t *

Ac c r, rdin- to a 1 ,9 survey sen B- iL, 'e on iikk' Ido l land !t, to v67
million cubic feet. In Lhk'tido, :'in veneer ri'.. up 21 pr rc t of the
native hariwujJ veneer i r 'luction and r recent of the pf,", od prcuc .
Th- 1)r, iu,'tion of 1.,.n veneer among te d to ., .]ion B .m'ire feet in
Itokkailo alone. About 70 percent 0f the 1,? ), board-f1et sen lumber
exporte.]i in 1 ,'.) came to the United States, and the reina.:..r went to .';uth
Af rica and I t 'rope.


Fric- R.'n-e.

SCn Is in the medluin price ra,;, .



Iden. t t".'l n.- '.i' ,p *r' ri ot i'Cs


American elm


I,.irt wood color


Stir in;w"-'cd, core zone

3uq-n rwolod !oree


\e 'ssl elements


Pale yellowish
br.' brown

SlnFli- row

In wavy tanr,-,n-
tial lines

Without s: 1r-l3


Brown


Sir,.;l.! row

In wavy tangen-
tial 1'.."s

With s; !ralt


- r '4


-*.veral rows

In short radial
grWups

Without .irals


Comimerc ial white ash can ordinarily be sei art.ed from '.r.because of the wider
zone of sprinrw ..4" j 4 I -_.4'
particularly If the wood surface has: h.er modifi-'d I',v bleaclir.,-', c 1.....-
and finis-ing. For accurate separation of elm and sen, it is usually .si-ira-
ble to examine the wood microscopically. Th- presence -," -iral thicl. '.l:1..3
in the vescel elements Indicates elm, and their ab..-,..e sen.


Rept. No. 1979--


Forest Froducts Research Institute. An outlinee of -; k.aitio Forestry.
Forest Products Rese-arch institute, H l.Io, Japan. A'.(-ut i -.


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1.-5











Table 1.--Strength properties of sen compared with American
elm and commercial white ash-1


Sen :American:Commercial


-- ----------------------------------- --------


Moisture content.......................... percent:

Specific gravity..................................

Static bending
Fiber stress at elastic limit............p.s.i.
Modulus of rupture....................... p.s.i.:
Modulus of elasticity.............. 1,000 p.s.i.:
Work to proportional limit......in.-lb./cu. in.:
Work to maximum load............ in.-lb./cu. in.:

Impact bending
Height of drop causing complete failure
(50-pound hammer)......................... in.

Compression parallel to grain
Fiber stress at proportional limit.......p.s.i.:
Maximum crushing strength................p.s.i.:

Compression perpendicular to grain
Fiber stress at proportional limit.......p.s.i.:

Shear parallel to grain
Maximum shearing strength................p.s.i.

Hardness
End ......................... . . ............ lb.
Side ........................................ lb.:


6
iC
3


4
6


12

0.45


,860 :
),56o :
.,430 :
1.92 :
9.2 :



26


,510
;330:
1,550


760


660


800
610o


I


elm : white ash


12 12

0.50 o.58


7,600 : 8,900
i,800 : 14,600
1,540 1,680
2.55 2.68
15.0 : 15.6



59 40


4,030 : 5,580
5,520 : 7,280


850 : 1,510


1,510 : 1,920


1,110 : 1,680
830 : 1,260


1Bruce, H. D., Cockrell, A., and Cummings, L.
--Bruce, H. D., Cockrell,, P. A., and Cummings., L.


Properties and Uses of


Commercially Important Japanese Woods. Natural Resources Section, General
Headquarters, SCAP, Report No. 147, October 1951.


Rept. No. 1979












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