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Tung Oil is
pressed from the nuts of Tung tree is known also
as
China wood oil and nut oil. Major producing countries
are mainland China (Guizhou, Guangxi , Sichuan , Hubei, Hunan,
Yunnan, Shaanxi, Jiangxi, Henan ) and South America (Argentina
and Paraguay), United States and Africa . Tung tree farms in
the southern U. S. and Argentina now supply tung oil,
formerly available only from China. The oil is still known in
some circles as "China wood oil".
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Tung oil is
an ideal "binder" or "vehicle", carrying the resins and driers
deep into the pores of the wood so that sealer and finish
coats practically become part of the wood - drying into an
armor-like yet beautiful surface.
Tung oil tree (Aleurites
fordii), a deciduous shade tree native to
China. It belongs to the Euphorbia Family (Euphorbiaceae) along with the candlenut tree (A
molucanna),
another species with seeds rich in unsaturated oils. For
centuries tung oil has been used for paints and
waterproof coatings, and as a component of caulk and mortar.
It is an ingredient in ink and is commonly used for a
lustrous finish on wood. Some woodworkers consider tung oil to
be one of the best natural finishes for wood. |
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Tung oil tree showing two male flowers and one
female flower (right) in which the petals have fallen off
exposing the pistil.
Other unsaturated plant
oils, such as castor oil and linseed oil, take longer to dry
and leave an oily residue until they soak into the wood
surface. Tung oil 's ability to dry quickly and polymerize
into a tough, glossy, waterproof coating has made it
especially valuable in paints, varnishes, linoleum, oilcloth
and printing inks. |
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Drupaceous
fruit and seeds of the tung oil tree. The oil-rich
seeds
are produced inside a thick, woody endocarp layer and
are the
source of tung oil used on fine
furniture.
The pit of a peach (Prunus persica)
showing the seed that is contained inside the hard, woody
endocarp layer. The endocarp is
the inner layer of the
fruit wall or pericarp. It is surrounded by a
fleshy
mesocarp and a thin outer skin or exocarp. Fruits with an
endocarp layer surrounding the seed are called drupes or
drupaceous. The endocarp protects and aids in the dispersal of
the |
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vulnerable seed, especially when it is
swallowed by a hungry herbivore.
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Tung oil is
composed primarily of eleostearic (elaeostearic)
acid,
with smaller amounts of oleic, linoleic and
palmitic glycerides. Eleostearic acid is a crystalline
unsaturated fatty acid that exists
in 2 stereoisomeric
forms: An alpha acid occurring as the glycerol ester
especially in tung oil, and a beta acid obtained from the
alpha acid by irradiation (9, 11, 13-octadecatrienoic
acid). The chemical structure of tung oil eleostearic
acid:
CH3(CH2)3CH=CHCH=CHCH=CH(CH2)7COOH |
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