Bamboo preservation
in Vietnam
Tang, Thi Kim Hong
PhD. studying place: Centre of Wood Science, University Hamburg
Leuschnerstr. 91
21031 Hamburg, Germany
Working place: Faculty of Forestry, Nong Lam University of Ho Chi Minh City
Linh Trung Ward, Thu Duc Distric
Ho Chi Minh City, Vietnam
BAMBOO RESOURCE AND UTILIZATION
IN VIETNAM
RESOURCE:
• Vietnam belongs to the countries with the largest bamboo
resources on the world (the Global Forest Resources Assessment 2005 of FAO)
• Vietnam has about 1,482,000 hectares bamboo forest and
around 81,500 hectares bamboo plantation.
• Vietnam has at least about 200 bamboo species of 30
genera. The important species for “timber” uses are Bambusa
asper, B. balcooa, B. bamlos, B. stenostachya, B. vulgaris,
Dendrocalamus asper, D. barbatus, D. longivaginus, D.
parvigemmiferus, Thyrostachys siamensis, and several species of
Schizostachyu and Dendrocalamus especially for housing.
UTILIZATION
• In Vietnam bamboo is available in suitable dimensions for a
reasonable price. Consequently, it is used for many
purposes, which range from the traditional utilization up to
the industrial production of parquet, furniture or bamboo‐
based panels and pulp.
• Until now, the processing and utilization of bamboo have
still relied on traditional practice, mainly for housing and
constructions, furniture making and interior decoration,
splits for utilities, agriculture crops, transport, fishing and
hunting, household things, electronic popes.
• In recent years, bamboo became the raw material for the
industrial manufacturing of round and laminated bamboo
furniture, parquet and pulp for export to the international
market(Japan, Korea, Taiwan, European countries, North
America, Canada, and Australia )
Importance of bamboo preservation
• Bamboo has a lower natural durability against fungi and
insects compared to wood
the service life of bamboo structures is often short.
• Vietnam has a tropical climate with high temperature and
humidity with advantageous conditions for moulds and insects
attack easily bamboo culms and products.
• According to a recent survey by Handicraft and Wood
Industry Association (HAWA) of Vietnam, one of the reasons
for a weak export of bamboo and rattan products is the
problem possible damage by mould and insect attack.
Treatment of bamboo raw material is an
important part of processing for bamboo products and
housing.
Methods of bamboo preservation in Vietnam
Non chemical methods (traditional method)
• Curing : culms are cut at the bottom and left on the
clump for some time with branches and leaves.
• Water‐logging: freshly bamboo culms are put into
running or stagnant water or even mud for 1‐3 months.
• Heating over open fire: heating over open fire after
applying oil on the surface
• Lime‐dipping/‐painting: bamboo culms, splits and
mats are dipped in lime CaO solution for 1 or 2 hours.
• Reduction starch content in harvested bamboos
Reduction starch content in harvested bamboos
Harvesting of bamboo during low‐sugar content season
Sugar content in almost all plants varies with season. In Vietnam, it is advisable to
harvest bamboo after the expansion of the new culms (from November through
March) because the starch content has been used up for the growth.
Harvesting of bamboo at completed growth
Sugar content in bamboos varies with ageing. It is lowest during the first year of
growth but felling of one‐year‐old bamboo has to be avoided because of low
strength and reduction of the next year yield. Bamboo normally matures at 3‐4 years.
Post‐harvesting transpiration of bamboo culms
Sugar content in bamboo culms can also be reduced by keeping fresh cut, culms
upright or leaning them against trees for a few days (see curing). Parenchyma cells in
plants continue to live for some time. During this period, the stored food materials
are utilized and the sugar or starch content in bamboos is lowered.
Advantageous and disadvantageous of traditional methods
Advantageous
The methods are mostly simple, require minimal equipment and
are easy to apply. They are acceptable for small quantity making
in rural areas. Some traditional methods are environmental
friendly.
Disadvantageous
Firstly, the traditional methods are not real efficient for bamboo
protection against fungi and insects.
Secondly, the treatment period is usually long and capacity of this
method is limited, which are unsuitable for greater production.
Therefore, for many fields of utilization chemical methods are
needed.
Chemical methods
Preservatives
•Boron compounds are most widely used for treatment
of rubber wood and bamboo in the South of Vietnam
and some places in the North.
•In the North of Vietnam, a chemical substance XM5
containing Cu‐sulphate and K2Cr2O7 is used for bamboo
preservation.
•Othere chemicals like sodium fluoride or creosote have
been but rarely applied. In Vietnam, Chromate Copper
Arsenate (CCA) has never been used.
Problems on preservatives
• Pentachlorophenol is a wood preservative effective
against mould and fungi and economical.
pentachlorophenol has been widely used in wood and
bamboo preservation in Vietnam for long.
• Pentachlorophenol is banned in most of the world as well
as in Vietnam
Bamboo manufacturers have pressing problems
on suitable bamboo preservation of products for export.
(For export in container most products need protection against moulds and
insects.
They are urgently waiting for a treatment method against mould with cost‐
effective and environment‐friendly.)
solution
• Therefore, the project:
” Investigation on treatment of some important
bamboo species of Vietnam against fungi” is
being undertaken at the Centre of Wood Science of
University Hamburg.
Impregnation methods
Non‐ pressure methods
•Soaking
Freshly culms after cut to desire length and branches removed as
well as bamboo splits are submerged in solution of boron
compounds 7% or chemical substance XM5 10% for diffusion. The
treatment time takes about 2‐ 3 days for splits and 7‐9 days for
culms
•Steeping or butt‐end treatment
Freshly cut culms with the
braches, soon after
harvesting are placed
upright in suitable container
(usually plastic buckets)
containing a solution of
boron compounds at 8% or
the chemical substance
XM5 15%. The butt‐end of
culm is kept immersed in
the treatment solution up
to about 25 cm. The time of
treatment may take 8‐14
days, depending on the
freshness and the length of
the culms as well as
preservative.
Gravity method (Vietnam‐method)
The principle of this method: the inner cavity of the culm, called
lacuna, is used as a reservoir for the treatment solution. The lacuna of
an internode of a fresh culm is filled with the preservative. It serves as a
vessel for moving into the inside wall, the parenchyma tissue and the
fibers and also into the vessels, in which it flows down by gravity.
In detail: the inner wall of this internode is generally scraped at a
depth of 1‐2mm or a round incision by a sharp tool to disrupt the
inner terminal layer. The culms are placed standing against a wall or
fence with a declination of at least 60 degree. The foot of culms should
be put into a plastic bucket to avoid pollution and to measure the out
coming of liquid. Finally, this internode is filled up with the preservative
solution. It is a daily need to observe the loss and to fill up this
internode. The impregnation period will be completed when drops
occur at the foot of culm, which have almost same colour as the initial
solution.
Pressure method
• In Vietnam, the full cell method is commonly applied in
bamboo treatment by boron compounds with concentration
3‐ 7% or the chemical XM5 8% in a cylinder with diameter
1.4 m and various lengths like 3.5m, 6.5m, 8m and 9.5 m.
This vacuum‐pressure process is conducted with 6‐7kg/cm2
pressure for 2‐3 hours.
• This schedule is mostly applied for bamboo species in
Vietnam
an improper pressure treatment like a high
pressure can cause defects of culms (cracks and collapse).
The defects happen particularly with thin walled species like
Schizostachyum polymorphum
• In fact, the pressure treatment schedule has to be related
to the properties of bamboo, mainly thickness of wall.
it is necessary to study the best preservative
treatment of bamboo species used.
•
Problems for bamboo preservation in Vietnam
• In Vietnam no national standards exist for wood and bamboo
preservation. Also, the general information on international
standards is not well introduced or known in Vietnam.
• The lack of information on preservative treatment relates to the
following areas:
Knowledge about possibilities for bamboo protection regarding
treatment facilities and preservative chemicals, such as preservatives being
banned national and international.
The advantages of bamboo preservation extending the service life of
bamboo structures, economics of bamboo preservation, its environmental
impact.
• Research on bamboo preservation in Vietnam relates only to the
treatment for construction in rural areas. No research project is
undertaken on bamboo preservation for industrial products like
parquet, furniture. Only recently some investigations have been
started.
CONCLUSIONS
• Bamboo is currently the major raw material in Vietnam
for a wide range of utilization from the traditional use
up to the industrial production.
• The biological durability of bamboo is relative low.
Therefore, protection of bamboo is an essential tool for
the quality of bamboo structures.
• For bamboo preservation, it concerns the quality of
the bamboo material to be treated, the choice,
concentration and uptake of the preservative and a
sufficient distribution within the culm tissue.
RECOMMENDATIONS
As an overview of the situation of bamboo industry as well as the
development of bamboo preservation in Vietnam, the following
steps are recommended:
• Attention to bamboo preservation such as basic and
systematic research on technology of bamboo
preservation by traditional as well as industrial
methods.
• Exchange of experience and cooperation within
industry and related institutions.
• International contacts such as IRG‐Conference and
World Bamboo Congress.
• Foreign advises by international organizations, like
INBAR, ITTO, FAO, and UNIDO.
RECOMMENDATIONS
As an overview of the situation of bamboo industry as well as the
development of bamboo preservation in Vietnam, the following
steps are recommended:
• Attention to bamboo preservation such as basic and
systematic research on technology of bamboo
preservation by traditional as well as industrial
methods.
• Exchange of experience and cooperation within
industry and related institutions.
• International contacts such as IRG‐Conference and
World Bamboo Congress.
• Foreign advises by international organizations, like
INBAR, ITTO, FAO, and UNIDO.
Acknowledgements
• Thanks to IRG for giving me the Award to
participate the Annual Meeting in Beijing on 24‐28
May 2009 as well as for presentation of the article.
• Grateful to Prof. Walter Liese, University Hamburg,
Germany, for his invaluable advice. And
thank you very much
for your attention!