Wood Properties of 5-year-old Fast Grown Teak

Abstract

Jati Unggul Nusantara (JUN) is one of fast growing plantation teak that has been widely cultivated in Indonesia. This teak has been developed to be harvested after 5 years when its diameter reaches 25-32 cm (diameter at breast high). The diameter of JUN is usually three times larger than the conventional plantation teak (teak cultivated from seed) at the same age, and the same as 30-40 year-old mature teak. Preliminary research was conducted to determine anatomical and selected physical properties of 5-year-old JUN teak, as well as its suitability for furniture production. The results revealed that wood color, texture, and grain pattern of JUN were slightly different from the mature conventional teak. The length of fiber cells was similar as in the mature teak. There were differences in ultramicroscopic structure of JUN: the mean micro fibril angle was narrower, and the crystallites degree was larger. Shrinkage values from green to 12% moisture content were: 0.70 (radial-R) and 1.62 (tangential-T), and from green to oven dry were 1.59 (R) and 3.29 (T). T/R ratio was 2.34. Specific gravity in air dry condition was 0.52. Based on the research results it appears that 5-year-old JUN may be suitable for the production of medium quality furniture products. More research is required to investigate and enhance the properties of JUN for high quality products.

Full text

Wood Properties of 5-year-old Fast Grown Teak 29
Ratih Damayanti, Barbara Ozarska, I Ketut N. Pandit, Fauzi Febrianto, and Gustan Pari
Wood Properties of 5-year-old Fast Grown Teak
Ratih Damayanti, Barbara Ozarska, I Ketut N. Pandit, Fauzi Febrianto, and Gustan Pari
Abstract
Jati Unggul Nusantara (JUN) is one of fast growing plantation teak that has been widely cultivated in Indonesia. This
teak has been developed to be harvested after 5 years when its diameter reaches 25-32 cm (diameter at breast high). The
diameter of JUN is usually three times larger than the conventional plantation teak (teak cultivated from seed) at the same
age, and the same as 30-40 year-old mature teak. Preliminary research was conducted to determine anatomical and selected
physical properties of 5-year-old JUN teak, as well as its suitability for furniture production. The results revealed that wood
color, texture, and grain pattern of JUN were slightly different from the mature conventional teak. The length of fiber cells was
similar as in the mature teak. There were differences in ultramicroscopic structure of JUN: the mean micro fibril angle was
narrower, and the crystallites degree was larger. Shrinkage values from green to 12% moisture content were: 0.70 (radial-R)
and 1.62 (tangential-T), and from green to oven dry were 1.59 (R) and 3.29 (T). T/R ratio was 2.34. Specific gravity in air dry
condition was 0.52. Based on the research results it appears that 5-year-old JUN may be suitable for the production of
medium quality furniture products. More research is required to investigate and enhance the properties of JUN for high quality
products.
Keywords: Young fast grown teak, anatomical properties, physical properties, super teak, conventional teak wood.
Introduction
Teak (Tectona grandis Linn. f) is a popular timber for
furniture, construction building, pole boat making and
luxurious veneer. Naturally, teak is harvested at
approximately 80 years old. Period of rotation in established
plantation forests such as in India and Indonesia is 50 to 80
years (Soerianegara and Lemmens 1994). This long rotation
in planting causes the price of teak wood to increase
significantly due to a limited supply. Iskak (2005) states that
the shortage of teak as a raw material is estimated at
approximately two million cubic meters per year.
Consequently, timber industries that use teak as a raw
material face difficulties in its continuous supply (Krisdianto
and Sumarni 2006).
This condition motivates the silviculturists to
investigate various methods which would allow establishing
a shorter rotation and a faster growth teak. One of the
methods already developed is through vegetative
cultivation, such as tissue culture, bud grafting, and shoot
cutting. As a result, the rotation of planting is decreasing
from 50-80 years to 20-40 years (Yunianti 2012). These fast
grown teaks are becoming a solution to overcome the teak
supply scarcity.
In Indonesia, there are many varieties of fast grown
teak that have been widely cultivated. Timber communities
call this timber “super teak”. One of them is Jati Unggul
Nusantara (now Jati Utama Nusantara - JUN). The
combination of breeding technology and intensive
silviculture treatment encourages the teak timber producers
to harvest the tree at a very young age, 5-year-old . At this
age, the average stem diameter is 20-30 cm which is the
same as 30-40-year-old conventional teak (Ministry of
Forestry 2012).
However, there is a common opinion that timbers
from fast growing or short rotation have inferior wood
properties, mainly in natural durability and timber strength
(Irwanto 2006; Kininmonth 1986). A faster growth will
produce shorter cells that reduce the wood quality (Brown et
al. 1994; Panshin et al. 1964). No matter how small the
changes, it will lead to differences in the macro, micro and
ultramicroscopic structures of the wood, which may cause
the alterations of material characteristics (Pandit and
Kurniawan 2008). This study aimed to determine anatomical
and selected physical properties of 5-year-old JUN teak, as
well as its suitability for furniture production.
Materials and Methods
Sample Preparation
Four and five year-old JUN were collected in
September 2009, located in Balapulang, Central Java
Province, Indonesia. While as comparison, 4 and 5-year-old
conventional teak were also collected in the same time from
Brebes, Central Java Province, Indonesia (at around 10 km
from JUN plantation). Wood samples in the disc form
measuring 10 cm in thickness were taken from the particular
tree heights i. e. bottom, middle and top portions of the
corresponding logs for anatomical observation and physical
properties investigation. Physical properties as examined
were green moisture content, density/specific gravity (SG)
and radial as well as tangential shrinkages. Sampling and
testing of its physical properties followed the ASTM 2007 D
143-94 Reapproved 2007. Remaining timber was used for
furniture manufacturing.

30 Wood Research Journal Vol.9 • No.2 • 2018
Anatomical Observation
Observation on anatomical structure covered macro,
micro and ultra microscopic characters. Macroscopic
characteristics involved appearance (including wood
discoloration), texture, lustrous, hardness and grain
direction. Observation on microscopic structure was
prepared by sectioning (Sass 1961) and maceration process
(modification of Franklin method in Damayanti et al. 2016),
covered cells dimension, cells structure (Wheeler et al.
1989), and juvenile percentage. The juvenile percentage
was determined with the aid of regression curve that related
the fiber length to the successive positions of wood segment
moving all the way from the pith to the bark in radial
direction (Darwis et al. 2005) following the growth ring.
Furthermore, ultramicroscopic characters assessment
covered micro fibril angle, chrystallite degree and sellulose
crystallite size using X Ray Diffractometer (Stuart and Evans
1994) from the pith towards bark following the growth ring,
taken from the early and late wood portions. Dimension of
cellulose crystallite in the cell wall was calculated by
Scherrer Formula (Andersson 2006):
Distance among cellulose crystallite was estimated by the
formula:
where K is a shape factor, the value is 0.9 to determine
sellulose crystallite dimension; λ is wave length of Cu; β
(= ) is FWHM value divided by 2 (in radian); and θ’ is
2 theta value divided by 2 (in radian).
Quality Assessment as Furniture
Some furnitures from JUN timber were manufactured
to evaluate the quality of JUN as raw material for furniture. A
set of quantitative criteria as minimum requirements for
wood as a raw material for furniture has been established by
National Standardization Board (1989). From physical
aspect, furniture components need to be produced from
timber with minimum strength class III and specific gravity
(SG) at least 0.40. Some interviews were also conducted to
gain opinion from an experienced technician.
Results and Discussion
Results assesment on wood properties of JUN as
furniture material are presented in Table 1. The criteria were
determined by Menon and Burgess (1979), PIKA (1979),
Pandit et al. (2009) and National Standardization Board
(1989). Macroscopically, JUN had straight grain direction
and sometimes interlocked, the same as 5-year-old
conventional teak, while mature teak had majority
interlocked grain direction. JUN also had coarse texture,
slightly glossy until opaque surface, light color and there
was a pattern in wood surface as a result of wood
discoloration (secondary heartwood) and multiseriate rays.
The latter two characteristics were not observed in
conventional teak (Fig. 1). The straight grain direction may
ease in furniture processing, and this is a positive aspect
because diagonal grain direction usually will reduce wood
strength (Pandit et al. 2009). The coarse texture in JUN will
affect in finishing process such as need more lavish filler or
putty, and it may make a problem in sherlak application.
Less natural lustrous in JUN requires more effort to increase
its luster.
Table 1. Timber properties requirement for furniture and asssement of JUN as furniture material.
Wood Properties
Desired Properties
JUN Properties
Macroscopic
structures
Straight grain direction, fine to
medium texture, good natural
lustrous, good color and appearance
Straight grain direction, coarse texture, slightly glossy
until opaque surface, light color and there was a pattern
in wood surface due to the presence of wood
discoloration and multiseriate rays
Microscopic
structures
Medium cell wall thickness, low
juvenile wood portion, no crystals ,
tyloses and silica
Very thin cell wall thickness, 100% juvenile wood
portion, no silica, and there was a presence of tyloses
Physical properties
Medium density/specific gravity (SG),
high dimensional stability
Shrinkage values from green to 12% moisture content
were 0.70 (radial-R) and 1.62 (tangential-T), and from
green to oven dry were 1.59 (R) and 3.29 (T). T/R ratio
was 2.34. Specific gravity in air dry condition was 0.52.
In conclusion, JUN has medium density/SG and rather
good dimensional stability

Wood Properties of 5-year-old Fast Grown Teak 31
Ratih Damayanti, Barbara Ozarska, I Ketut N. Pandit, Fauzi Febrianto, and Gustan Pari
Figure 1. Wood discoloration as a result of secondary heartwood in 5-year-old JUN; compared to 5-year-old conventional
teak where the discoloration or secondary heartwood formation was not observed (arrow).
The parts of furniture intended to accept loads, either
continuously or intermittently. These loads are evenly
distributed including on the connection. Thus, although the
strength is important, it is not considered necessary really
very strong raw material. Furthermore, wood strenght
usually associated with wood density, in consequence, very
strong wood means very heavy timber. Furniture made of
heavy wood is generally less desirable because it is difficult
to move. Besides a complicate removing, heavy timber also
causes rapid blunting of the knife. Wood with dry oven
density in approximately 0.5 g cm-3 has proven to be quite
good for furniture (Menon and Burgess 1979).
Air dry density of JUN was 0.52 g cm-3 with specific
gravity 0.48, and it makes 5-year-old JUN will quite ideal to
be used for furniture. Although it is advisable to use a timber
with larger specific gravity for products that endure heavy
load, 5-year-old JUN can be used to manufacture furniture
for home and office, such as desks, cabinets, shelves,
including bookcases. So far, the manufactured product is
strong enough to support loads.
Wood for furniture should be easy to sawn, planed,
polished or drilled (Menon and Burgess 1979). In this study,
machining properties were not studied quantitatively. Wood
surfaces should be smooth with no tear grain that will result
in a hairy surface. Qualitatively, at planing process, JUN
was easily planed and produced an even surface. It was
possibly due to the straight direction of wood grain and the
smaller crystal size. Selulose crystallite dimensions for JUN
were 5.9 nm (thickness) and 17.78 nm (length) with distance
among crystallite was 0.3913 nm, while, thickness, length
and distance of crystallite sellulose for conventional teak
were 6.36 nm, 23.88 nm, and 0.3938 nm, respectively. In
sawmills process, rough surface of JUN made it rather
difficult to sawn. The technician called the wood processing
properties of JUN was like Dryobalanops wood, and it was
possible because there was a similarity in their vessels
pattern.
Juvenile portion both in JUN and conventional teak
were 100%. This high juvenile wood percentage will
decrease its quality as furniture. Characteristics of juvenile
wood generally have a low density, high moisture content,
and high longitudinal shrinkage; making it is easy to deform.
The most feared nature of juvenile wood is disabilities called
brittle, especially for structural timber, so its use as
component for construction is not recommended (Anisah
and Siswamartana 2005). For the furniture industry, wood
with a high percentage of juvenile wood would also tend
causing a lot of problems during the processing. However,
in the same age, JUN has more declivous regression line
(Fig. 2). It meant that JUN may reach a wood maturity
faster than conventional teak wood, however it needs more
study on the older ages. Furthermore, the narrower MFA of
JUN enables JUN to overcome the high longitudinal
shrinkage in common wood. MFA of JUN was 22.09° while
conventional teak was 25.29°. Another study stated that
MFA of 7-year-old fast growing teak from Penajam, East
Borneo, was 23.29°, decreasing from pith to bark, while
MFA of 7-year-old conventional teak was smaller, 22.05°,
with the same pattern (Krisdianto 2008). The narrower MFA
in JUN was predicted as a result of shoot cutting cultivation
technique from mature parent trees and a combination with
compound support root (Fig. 3) that enables JUN has
narrower MFA without having broken in the early growth.

32 Wood Research Journal Vol.9 • No.2 • 2018
Figure 2. Regression curves of the fiber length from pith towards bark for 5-year-old JUN and conventional teak. It appears
the trend is still pointing upwards, yet there is a constant point. It can be seen that the fiber length of JUN started
above 1200 µm (similar as in mature teak), and fiber length addition of JUN is more sloping than conventional teak.
JUN may reach a wood maturity faster than conventional teak wood.
Figure 3. Compound support root in JUN enables JUN has narrower MFA without having broken in the early growth.
Table 2. Radial (R) and tangential (T) shrinkages of 4- and 5-year-old JUN and conventional teak wood
Type of Teak
From green to 12% moisture content
From green to oven dry
T/R ratio
R
T
R
T
JUN
0.70
1.62
1.59
3.29
2.34
Conventional teak
1.88
3.03
2.77
4.43
1.68

Wood Properties of 5-year-old Fast Grown Teak 33
Ratih Damayanti, Barbara Ozarska, I Ketut N. Pandit, Fauzi Febrianto, and Gustan Pari
Qualitative testing for JUN hardness showed that JUN
had low hardness. Positively it may ease the wood
processing including the drilling, however negatively its
strength on nails holding may rather weak. Weakness in
nails holding and easier drilling properties were due to the
very thin wall of JUN’s cells.
Timber for furniture raw material should not contain to
much wood extractive such as resin, and also silica because
it will accelerate blade blunting. Since JUN was harvested in
very young age, macroscopic observation showed that
extractive and silica content was low, and it will ease in
processing.
Timber with high shrinkages will not be preferred for
any utilisations. Dimensional alterations will cause distorsion
in furniture component, hard to pull the drawers, hard to
open cupboard’s door, and sometimes open wood joints
(Menon and Burgess 1979). Average shrinkages values
from green to 12% moisture content and from green to oven
dry for 4 and 5-year-old JUN and conventional teak wood
presented in Table 2. T/R ratio for JUN was 2.34 while
conventional teak was 1.68. The conventional teak wood
had very good dimensional stability, whereas T/R ratio of
JUN that was above 2 but under 2.5 showed that JUN had
medium stability. An effort, such as an appropriate drying
treatment or quality enhancement treatment such as
densification and impreganation (Corryanti and Muharyani
2018) absolutely is needed to increase the wood
dimensional stability of 5-year-old JUN.
Particular attention, however, must be applied when
the wood furniture will be used in air-conditioned room.
Therefore, wood with low shrinkage is ideal for furniture
production. Changes in water content of the dried wood can
be minimized by using proper coating varnish, paint, or even
a plastic sheet. The latter method is the latest development
in wood protection techniques. If possible, the board should
use radial board because it has a smaller shrinkage (Menon
and Burgess 1979), and the radial shrinkage of JUN was
very high due to the wider rays, higher crystallite degree,
and narrower micro fibril angle (MFA). Crystallite degree
and MFA of JUN was 43.89% and 22.09°, respectively,
while conventional teak was 40.32% and 25.29°,
respectively.
In conclusion, regarding to its properties, 5-year-old
JUN may be used as raw material for furniture.
Requirements in terms of strength, wood processing, wood
density, and dimensional stability were met the minimum
limit even though there were weakneses in nails holding
strenght and lavis finishing. Teak popularity enables JUN
with a lower hardness and lighter wood properties
sometimes preferably to use because easier to processed
and moved. In terms of appearance, its quality as a luxury
product will decrease, especially for furniture that requires
wood beauty, as of, JUN more suitable for making light-
colored furniture that is preferred by certain consumers.
However, there is a possibility that its appearance will
appeal if used at an older age.
Conclusions
Efforts to accelerate teak growth in Jati Unggul
Nusantara led to changes in the anatomical structure of
wood and some properties. Until the age of 5 years, input
technologies given can improve the properties of the wood
to the ultrastructural level where the mean micro fibril angle
was narrower, and the crystallites degree was larger. The
properties of JUN will facilitate JUN as raw material for
furniture, although there was a decrease in appearance and
wood texture.
Acknowledgements
Authors would like to thanks to PT. Setyamita Bakti
Persada and Unit Bagi Hasil KPWN Ministry of Forestry,
Indonesia, especially to Bapak. Hariyono Setiyono, Bapak.
Rafik and Bapak. Baghya Siregar for their help in wood
sample collection.
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Ratih Damayanti
Plant Anatomy Researcher,
Forest Products Research and Development Centre,
Ministry of Environment and Forestry,
Jl. Gunung Batu No. 5, Bogor, Indonesia.
E-mail: ratih_turmuzi@yahoo.com,
Barbara Ozarska
Professor,
Dept. of Forest and Ecosystem Science,
The University of Melbourne,
Burnley Campus, Richmond, Victoria, Australia.
E-mail : bo@unimelb.edu.au
I Ketut N. Pandit
Professor,
Forest Product Dept., Forestry Faculty,
IPB University,
Darmaga Campus, Bogor, Indonesia.
Fauzi Febrianto
Professor,
Forest Product Dept., Forestry Faculty,
IPB University,
Darmaga Campus, Bogor, Indonesia.
E-mail : febrianto76@yahoo.com
Gustan Pari
Forest Products Research and Development Centre,
Ministry of Environment and Forestry,
Jl. Gunung Batu No. 5, Bogor, Indonesia.
E-mail : gustanp@yahoo.com