The Many Uses of Barks
The term bark loosely refers to the outer covering of the stem and branches. Technically, it
includes all the tissues from outside the cambium to the outermost layers of a woody stem.
The bark serves as a protective tissue. It acts as a conduit transporting food to the other parts
of the tree. About 8% of the total volume of a tree in bark.
Bark consists of an outermost corky layer called epidermis, a layer of manufactured
food-conducting tissues called phloem, a zone between these two layers known as cortex. In
several species, a layer of fibrous strips called “bast fiber” forms an innerbark. Oils, resins,
tannins, waxes and phenolic substances may be present in the bark.
Cork, fiber, tannins, gums, resins, latex materials can all be derived from barks. The most
common yet the oldest and lowest grade uus of unprocessed bark is for fuel.
Following are some of the other uses of barks:
1. Bark rich in tannin – a substance used in:
a) tanning leather, preparation of binders and wood adhesives, drying fishnets, ropes, soils
and clothing.
b) insecticide
c) rust prevention
d) ink manufacture
e) medicines
The barks of kamatchili, some mangrove species like ‘bakawan-babae’, busaing, langaral,
pototan and ceriops tagal are the main sources of tanning materials.
2. Bast fiber – another portion of the bark found just under the outer bark – strong, tough and
durable and can be made into cloth, turinas, bowstrings, fish lines, sacks. Paper from
mulberry and salago have fine bast fibers which can be made into high grade quality paper
such as bank notes and checks.
Those of kalulot and other similar species are made into lady’s handbags, wallets and
placemats.
Bast fibers of anonang, malabuho, and sinaligan yield silky and lustrous interlaced filaments
which are pliable and strong. These can be used in the manufacture of elegant hats,
handbags, placemats and wallets.
Anabo, anonang, ‘kulantingan’, ‘malubago’ and sinaligan have tough and durable bast fibers
with good folding endurance and bending sterngth. They can also be made into cordage and
wild bag trap.
3. Barks can also be potential sources of saponins – a lathe-producing substance which can
be used in the formulation of shampoo.
4. Barks which are crispy are good for making charcoal briquettes.
5. Barks contain phenolic constituents of the condensed types which can be utilized for
bonding upon addition of formaldehyde and proper application of heat and pressure.
This self-bonding characteristic of bark makes it a potential source of adhesive for plywood,
particleboard, hardboard and other similar products.
Barks of red lauan was used to test the potentials of fabricating boards from bark using its
own phenolic constituents as the bonding agent. A one-layer barkboard with smooth and
seemingly well bonded surface was produced using finer bark particles.
6. Barks shredded to resemble coarse hay can be used as soil conditioner, mulch or as
growing media for plants.
Seeds sown in seedbeds treated with decomposed Benguet pine bark was found to have a
germination period of 16 days only while those in untreated seedbeds took 20 to 23 days to
germinate. This was based on the study conducted by the Dept. of Environment and Natural
Resources (DENR).
7. Bark is also a good chelating agent. The tannin in bark could form chelates with heavy
metal cations and can help retain important minerals in the soil.
8. Bark can also form complexes with soil nitrogen compounds and prevent their rapid
breakdown.
9. Because bark improves drainage in certain soils, it has also been found to reduce root
know, damping off, and wilt.
PCARRD Monitor
Sept-Oct 1990