r n w# IT n LIiLir r nI
Bulletin No. 11
A New Industry in Florida
JOHN M. SCOTT
STATE OF FLORIDA
DEPARTMENT OF AGRICULTURE
NATHAN MAYO, Commissioner
Prepared and Published in Co-olperation with the College of
Agriculture, University of Florida, Gainesville.
DEPARTMENT OF AGRICULTURE
Nathan Mayo, Commissioner of Agriculture .................. Tallahassee
T. J. Brooks, Director, Bureau of Immigration .......Tallahassee
Phil. S. Taylor, Advertising Editor ... Tallahassee
John M. Scott, Agricultural Editor.. Gainesville
Fig 1,-Part of oan ,Sacre grove of young tung oil trees in Alachua County, Courtesy Florida
A New Industry in Florida
BY JOHN M. SCOTT
Prepared and Published in Co-operation with the College of Agriculture,
University of Florida, Gainesville
THE GROWING of tung oil trees in Florida is a new in-
dustry. The first trees in the State were not planted
until 1906, and only one small commercial planting was
made before 1923. The earliest of the larger commercial plant-
ings came into bearing for the first time in 1928 in sufficient
quantity to warrant the erection of a crushing plant in Florida.
In the fall of 1928 the building of a crushing plant was started
in Alachua county, which will extract the oil from the nuts
in commercial quantities (See Fig. 13). The early experimental
plantings looked promising enough in the past to warrant an
increase in commercial plantings from 140 acres in 1924 to
4,000 acres in 1928.
Scattered plantings of tung oil trees are found in nearly
all parts of Florida, although at the present time the large
commercial plantings are confined very largely to Alachua
and adjoining counties. This, however, does not mean that
later on commercial plantings may not be made in other parts
of the State.
TUNG OIL IN THE UNITED STATES
Tung oil seeds were first brought to the United States in
1905 by Dr. David Fairchild of the Bureau of Plant Industry,
United States Department of Agriculture. The first seeds were
secured from Consul General Wilcox of Hankow, China, and
were planted in California.
The first tung oil trees in Florida, according to available
records, were planted in 1906 by Messrs. W. H. Raines of
Tailahassee and S. H. Gaitskill of McIntosh. Mr. Gaitskill
made a second planting in 1908. About one hundred trees
DEPARTMENT OF AGRICULTURE
were also planted by Mr. Geo. B. Perkins of Tallahassee in
1912, and a few trees were planted the same year on the Florida
Experiment Station grounds. Dr. Tenant Ronalds of Talla-
hassee made a planting in 1913. From 1914 to 1920 some 3,000
to 3,500 trees were planted in various parts of the State. The
following is an approximate census of the trees growing in
tung oil groves in Florida: In 1923, 14,000 trees; 1924, 39,000
trees; 1925, 102,000 trees; 1926, 200,000 trees; 1927, 300,000
trees, and 1928, 400,000 trees. In the fall of 1927 approximately
30,000 new trees came into bearing, and in the fall of 1928 the
bearing trees in the State numbered about 160,000.
In addition to the plantings made in Florida, plantings were
also made in Alabama, Georgia, Louisiana, Mississippi, North
and South Carolina, Texas and California. It seems that Flor-
ida is the only State, however, where any extensive plantings
have been made.
The plantings in all of the above States were of value since
they showed where the tung oil tree could be grown most suc-
cessfully in the United States. Notwithstanding the fact that
tung oil trees were first planted in California in 1905, today
there are very few tung oil trees in that State. This is due
to the fact that California climatic conditions are not conducive
to the best growth of tung oil trees. For the same reason the
tung oil tree has not been found adapted to Alabama, Georgia,
Mississippi, South Carolina, and the other States that have
tried to grow them. Florida is the only State where the trees
have continued to grow and produce fruit in large enough
quantities to warrant increased plantings.
WORK AT THE FLORIDA AGRICULTURAL EXPERIMENT
The Florida Agricultural Experiment Station began work
with tung oil trees in 1912. In 1912 and 1914 ten trees were
planted on the Experiment Station grounds which served as the
beginning of the investigational work with tung oil. Since
1914 additional plantings have been made from time to time
on the Station grounds.
As soon as the first trees came into bearing, the Experiment
Station made chemical analyses of the nuts to determine the
oil content. Analyses were also made of the residue, which
showed its value as a fertilizing material.
As the plantings on the Station grounds were increased.
fertilizer experiments were started, and are still in progress.
to determine how to fertilize these trees so as to produce the
TUNG OIL, A NEW FLORIDA INDUSTRY 7
best growth of tree and at the same time produce the largest
yield of fruit with a high oil content.
In addition to the experimental work, the Experiment Sta-
tion has distributed a large quantity of tung oil seed as well
as many trees to interested people throughout the State.
In 1924 the Florida Experiment Station published the first
experiment station bulletin on tung oil, which presented to the
public the findings of the station up to that time. The active
part that the Experiment Station has taken in carrying on
experimental work and in distributing tung oil seed and trees
throughout the State is largely responsible for the develop-
ment of this new industry in Florida.
"The rather excellent showing made by the bearing trees
on the Experiment Station grounds, together with the Station's
demonstration of the relative ease with which the young trees
may be grown in the nursery, has attracted the attention of
horticulturists as well as manufacturers who have occasion to
use tung oil in their operations.* This also has raised, quite
naturally, the question as to whether it is possible to produce
tung oil profitably in this country. Conditions in China make
an assured and adequate supply of oil from that country more
or less uncertain. The imported oil is frequently inferior in
quality or is adulterated, and prices therefore are subject to
sudden changes. An American source of supply is much to be
desired and, if such can be developed, it will doubtless go far
toward stabilizing and insuring the future welfare of the paint
and varnish industries."
OTHER FLORIDA PLANTINGS
"To the enthusiasm and experimental work of the late
William H. Raynes, a well-known horticulturist of Tallahassee,
is due much of the credit for what developments have already
taken place in connection with the tung oil tree in Florida.*
Mr. Raynes was undoubtedly the first to attempt the growth
of the tree in the South. On November 15, 1906, he planted
five one-year-old trees which had been sent by the Department
of Agriculture to the superintendent of the cemetery at Talla-
hassee and which, in turn, had been given to him."
"In 1913 Tenant Ronalds, of Tallahassee, became interested
in the tung oil tree and planted four acres.t This was to be-
come the first bearing tung oil grove in Florida. In 1915 he
increased his plantings to 40 acres. The grove was well cared
for until the freeze of 1917, when young nursery stock and
Florida Experiment Station Bulletin No. 171, "The Tung Oil Tree
in Florida," p. 212.
t Ibid., p. 215-216.
DEPARTMENT OF AGRICULTURE
Fig. 2.-The first tung oil tree planted in Florida. This tree was planted near Talla-
hassee November 15, 1906, by the late W. H. Raynes.
TUNG OIL, A NEW FLORIDA INDUSTRY
young grove trees were killed. Since 1917 no care has been
taken of the grove except that a portion has been kept mowed
and pastured. Portions of it have burned over occasionally
and ten acres have been entirely removed. However, some of
the trees are still in good condition and bear fair crops, con-
sidering the lack of care and fertilization."
About 1917, B. F. Williamson, of Gainesville, became inter-
ested in tung oil from a commercial point of view. Mr. Wil-
liamson, who is an oil chemist, was primarily interested in the
quantity and quality of oil that could be obtained from this
new tree. From 1917 to 1923 he visited every planting of tung
oil trees in the Southeastern States. On these visits he took a
great many notes and at the same time obtained a great deal
of information from the various planters. During this same
time Mr. Williamson planted a large number of tung oil seeds.
The seeds for his early plantings were obtained from various
sources, a large part coming from the early plantings at
Tallahassee and from the Experiment Station at Gainesville.
With the information he had gathered about tung oil, Mr.
Williamson was able to interest some of the paint and varnish
manufacturers in planting a large acreage to tung oil trees in
Florida, which today totals about 4,000 acres.
AMERICA'S DEPENDENCE ON THE CHINESE PRODUCT*
"Tung oil, or, as it is commonly known in the United States,
China wood oil, was first introduced into this country from
China about the year 1869, the first shipment on record having
been valued at $62. During that year, 138,635 pounds, with
an invoice value of $53,641, was entered. It was not, however,
until after 1905 that the value of this material was really ap-
preciated and it came into widespread use. Even for some
years after this expansion technologists disagreed as to the
merits of tung oil for varnish manufacture, but today it has
practically revolutionized this industry.
"For centuries tung oil has been known to the Chinese and
widely utilized. Applied directly, it is used as a varnish on
their junks and other water craft and either in a crude, adul-
terated or prepared state on houses and furniture and for
waterproofing cloth, silk or paper. The imperfect combustion
of the residue resulting from the settling of the oil is the basis
for india ink. The ash resulting from burning the oil, mixed
with the oil, makes a pasty substance which is used for calking
the seams of boats or as a filler for preparing surfaces for
*Taylor, W. M., "China Wood Oil," Miscellaneous Series No. 125,
Department of Commerce.
10 DEPARTMENT OF AGRICULTURE
painting. It is because of its multitude of uses in connection
with wood that it has gained the name of wood oil.
"In the United States tung oil is a valued ingredient of the
types of varnishes which must be water-resisting and enduring.
In addition to being used direct, large quantities of these var-
nishes so prepared form a part of many paints and enamels
used by our modern industries. The use of tung oil in the
manufacture of linoleums, oilcloths, etc., has increased greatly
the quality of these products.
"Although a period of over 53 years has elapsed since the
introduction of wood oil, China is still our primary and prac-
tically our only source of supply. So it will be seen that, in
spite of its importance, American users are still utterly de-
pendent upon Chinese growers of the tree which yields the
fruit from which tung oil is extracted."
The figures for the imports of China wood oil into the United
States for the years 1922-1927 inclusive are given in Table 1.
TABLE 1. Imports of China Wood Oil Into the United States.*
Year Pounds Value
1922 ....... .......... ........ 79,089,293 $ 7,891,251
1923 ....................... 87,291,675 13,397,000
1924 ......... .... ....... ......... 81,587,854 11,091,776
1925 .-. ..... .. .......... .... ........ 101,553,519 11,385,848
1926 -.... .. ...... .. ................ 83,003,774 9,148,090
1927 ................ .......... ................ 89,650,411 11,809,583
Figures supplied by Chemical Division, United States Department
The tung oil tree is apparently able to adapt itself to a
variety of soils, but does not thrive in lime or phosphatic lime-
stone soils, or where the water table is too close to the surface.
In China, their native home, the trees grow in clay sand soils.
In Florida, however, they grow in any well drained soil that
is slightly acid. There is, nevertheless, actual evidence that
the presence of lime in the soil or subsoil so that the roots
come in contact with it retards the growth of the trees. Sandy
loam soils, such as are suitable for growing corn and cotton,
should be suited for the growing of tung oil trees.
In choosing a location for planting tung oil trees, it is im-
portant to keep in mind the fact that the land must be well
drained. Poor drainage is just as detrimental to tung oil trees
TUNG OIL, A NEW FLORIDA INDUSTRY 11
as to corn or cotton. Therefore, if the land is not naturally
well drained, one must see to it that there is sufficient slope
to the land so that drainage ditches may be constructed.
PREPARING THE LAND FOR PLANTING
As previously stated, it is necessary that the land be well
drained. If the land is not naturally drained, all needed ditch-
ing should be done before the actual preparation of the land
The preparation of the land for planting tung oil trees should
be similar to that for planting any farm crop. The ideal way,
and one that it is advisable to follow, is to plow the land broad-
cast early in the spring, usually during February or March,
plowing to a depth of six inches or more. After this plowing,
the land should be harrowed so as to have a smooth surface
and at the same time making a good seed bed. About the last
of March or early in April, a good legume should be planted
as a cover crop, such as cowpeas, velvet beans, beggarweed or
crotalaria. These are all good cover crops, but in the majority
of cases velvet beans and crotalaria are likely to be found
In the late fall, generally October or November, the cover crop
should be plowed under and the land prepared for the planting
of the tung oil trees. In preparing the land, after the cover
crop has been thoroughly plowed under, it may be necessary to
disk the land and then harrow.
The tree rows should next be laid off. It will be advisable
to use a transit for this so as to have the rows straight and
of uniform distance apart.
From observation and experience, it would seem that there
are several factors to take into consideration before deciding
definitely as to the distance apart to plant the trees. First, the
trees begin to bear at an early age, generally when about four
years old, and will bear very satisfactory crops for several
years before they reach their maximum growth. Second, the
annual value of the crop is low when compared with the value
of some of the fruit crops. It is therefore important not only
to make sure of as long life of the tree as possible, but also to
get the maximum yield of nuts from the land. It seems that
the maximum yield can best be secured from a given area by
planting in rows thirty feet apart and the trees twelve and a
half feet apart in the row, thus requiring 116 trees to the acre.
This means that from four to five crops of nuts can be pro-
12 DEPARTMENT OF AGRICULTURE
duced before the trees begin to crowd much in the row. When
the trees are large enough to begin crowding each other, every
other tree can be removed. This will leave the trees in grove
formation thirty by twenty-five feet. If care is taken in re-
moving the trees, they can usually be safely reset in some
other location on the farm.
Another advantage in planting the trees close together and
then removing the alternate ones is that, since some trees are
much more prolific bearers than others, one is able to save only
the most prolific trees and discard the boarders. The results
so far have indicated that the most prolific bearing grove can
be obtained at the least cost in this manner.
If the grower does not care to remove every other tree, the
trees should be planted 30 x 25 feet when they are set out,
which will eliminate crowding as the trees get older. Trees
on good land and that have been well cared for should occupy
the entire ground when set 30 x 25 feet by the time they are
fifteen years of age.
Planting the seed in a nursery is the most practical method
of propagation. The tree in its native country has been propa-
gated from seed for many years. It is possible to increase the
production of fruit by selecting seed from the best producing
The trees may be budded or grafted, but to do this success-
fully the services of an experienced budder are necessary.
Seed planted in the nursery should be planted in rows 31/2
to 4 feet apart and 10 to 12 inches apart in the row. After
one to two years' growth in the nursery, the trees may be
transplanted to the grove, but vigorous one-year-old trees are
most desirable for transplanting.
Best results will be obtained if the trees are transplanted
during the season of the year when they are dormant, which
is during December, January, and February. The method of
handling tung oil trees from the nursery to the grove should
be the same as for any other nursery stock.
Care must be taken in digging so as to retain a good root
system. The roots must be kept moist and protected from
direct rays of the sun, as a brief exposure to the direct rays of
the sun will prove detrimental to the young trees. Transplant-
ing should be undertaken when there is sufficient moisture in
the ground to insure growth of the trees. If the soil becomes
TUNG OIL, A NEW FLORIDA INDUSTRY 13
dry, it will be found necessary to water the trees until the rain-
fall is sufficient.
When nursery stock is dug, the trees should always be cut
back to a height of twelve to eighteen inches so as to insure a
low branching tree.
Before the trees are carried to the grove, the rows should be
laid off and staked out, and a supply of water should be on
hand. The trees must not be set too deep, but should be set
a little higher than they grew in the nursery. More trees are
lost from too deep than too shallow planting.
Fig. 3.-A tung oil nursery. Courtesy B. F. Williamson.
In the spring after the trees have been set out, the ground
between the rows should be prepared and planted to some good
cover crop. A space should be left about six feet wide on each
side of the tree row to be cultivated during the entire summer
and early fall. The cultivation may be done with an acme
harrow. The harrow should be used often enough, generally
every week or ten days, to keep down weeds and grass.
It is preferable to grow a cover crop between the rows of
trees each year until the trees become so large that they shade
the ground too much for cover crops to grow satisfactorily.
DEPARTMENT OF AGRICULTURE
Fig. 4.-Tung oil trees about sixteen years old growing on Florida Experiment
Station grounds-planted too close for best growth. Photo taken November, 1928.
TUNG OIL, A NEW FLORIDA INDUSTRY 15
The tree rows should also receive cultivation each year, but
the cultivation must be shallow enough so that the roots will
not be injured. After the trees are ten or twelve years old,
there is some question as to whether it is advisable to continue
The importance of growing cover crops among tung oil trees
cannot be over-emphasized. All good farmers know that the
better the land they have, the better crops they are able to
produce. The only way to make any permanent improvement
in the soil is by adding humus in some form. Humus is gen-
erally added most economically to the soil either by applying
barnyard manure or by growing cover crops. At the present
time, barnyard manure is scarce and high-priced in Florida.
The growing of cover crops is therefore the most practical way
of improving the soil in a tung oil grove.
The first four or five years after tung oil trees are planted
in a grove, they do not occupy more than one-half the ground.
The space that is not occupied, if not planted to some cover
crop, must be cultivated a number of times each spring and
summer, or allowed to grow up in weeds. The practice of clean
culture in Florida depletes the land as much or more than if
a crop had been grown on it. There are a number of summer
legumes that can be grown to good advantage as a cover crop.
Cowpeas, velvet beans, beggarweed and crotalaria are among
FERTILIZING THE TREES
Sufficient experimental data is not available at the present
time to enable one to say just what formula or what amount
of fertilizer is best to use on tung oil trees. Analyses have
shown that 5,000 pounds of nuts or seed take from the soil
approximately 106 pounds of nitrogen in terms of ammonia,
30 pounds of potash, and 68 pounds of phosphate. In addition,
the tree in making its wood, leaves, and outer shells of the nuts
requires still larger amounts of these ingredients each year. A
formula analyzing about 5 percent ammonia, 7 percent phos-
phoric acid, and 2 percent potash is most generally recom-
mended to supply the needs of young trees. When the trees
have reached bearing age, the percent of potash and phosphate
should be increased. For young trees it is preferable to have
the major portion of the ammonia from organic sources.
The trees should ordinarily receive two applications of fertil-
FIg1 5-A tuog oil grove In Levy and Mirloo Countlei Plantd Janiry, la1. Photographed Juo, 198 Courtesy B. F.
TUNG OIL, A NEW FLORIDA INDUSTRY
izer each year. The first application is usually applied soon
after the trees are planted, generally in April or May. At this
time about one-half to one pound per tree is recommended. A
second application of one-half to one pound per tree should be
applied during June or early in July when the summer rains
begin. After the first year, the spring application should be
applied in February. The amount generally applied at this
time as about one to one and a half pounds per tree, and a sec-
ond application of about the same amount per tree should be
made in July. Four-year-old trees should be given about two
to three pounds of fertilizer at each application. As the trees
begin to behr fruit, the amount of fertilizer should be increased
in proportion to the amount of fruit they produce. Eight- to
ten-year-old trees, if bearing good crops of nuts, should receive
about 10 to 12 pounds of fertilizer a year.
Fig. 6.-Cover crop of crotalaria sericea in tung oil grove.
It has been demonstrated that the residue from the pressing
of the tung oil nuts is valuable as a fertilizer, particularly in
adding nitrogen to the soil. By returning the residue to the
soil, and at the same time growing cover crops in the grove,
a large part of the nitrogen in the purchased fertilizer can be
eliminated. The addition of potash and super-phosphate will,
Fig, 7-Tung oil flowers, Pistillate (female) three upper flowers; staminate (male) two lower
M A -~. -.. . 1. .1
TUNG OIL, A NEW FLORIDA INDUSTRY 19
therefore, keep the elements of the soil balanced for the growth
of the tung oil trees. The young trees, of course, will seldom
bear sufficient fruit to cause the residue to have much effect,
but in full bearing trees the residue will be in large enough
quantities to have material effect upon the fertility of the soil.
When tung oil trees have been well cared for and have made
a good growth, a fair crop should be produced the fourth
year. A fair crop is generally considered to be from 3 to 6
pounds of fruit per tree, or from 250 to 700 pounds per acre,
depending upon the number of trees per acre.
A ten-year-old tung oil tree may yield anywhere from 25 to
75 pounds of nuts, although some individual trees have been
known to produce 150 pounds of nuts. Investigations so far
would seem to indicate that under ordinary conditions, an acre
of ten-year-old trees may generally be expected to average
about 20 pounds per tree. Allowing 60 trees to the acre, this
would give an average yield of 1,200 pounds of nuts per acre.
Records kept by B. F. Williamson on 109 trees nine years of
age and over have credited this group of trees with a yield of
above 5,000 pounds of dried fruit, equivalent to over 1,000
pounds of oil, on each of two different years. On another plot
of 1.9 acres, three-year-old trees yielded 1,096 pounds of fruit
or 576 pounds per acre, equivalent to 115 pounds of oil.
The young fruit is a dark olive green, which turns to a dark
brown color as maturity is reached. The mature fruit reaches
a diameter of from two to three inches and resembles somewhat
a small apple in shape. The fruit may grow either singly or
in clusters of two or more. Five or more brown seed are gen-
erally found in each fruit surrounded by an outer portion or
husk. The seed is somewhat like a large castor bean in shape
and color, while the meat is white and very oily.
SEED IN A BUSHEL
"Unhulled, dried fruits (nuts) from different trees have
been found to vary in number from 340 to 450 to the bushel.*
Of several bushel lots which were weighed and counted, the
weights, regardless of number of fruits required to make a
Annual Report, 1925, Fla. Exp. Station, p. 66-R.
NOTE-There is a difference of opinion as to the number of trees
which should be planted to the acre. Some plant as many as 120 trees
to the acre. Perhaps between 60 and 120 would be nearer correct.
Fig, 8-A bearing tung oil grove, Courtesy B, F, Williamson,
TUNG OIL, A NEW FLORIDA INDUSTRY
bushel, were almost identical-the average being 303/4 pounds.
The average bushel contained 17 pounds 10 ounces of seed and
13 pounds 2 ounces hulls. The number of seed obtained from a
bushel of fruit in hull varied from 1,780 to 2,000 with an ap-
proximate average of 1,900. One pound of such seed varied
in number from 108 to 142.
"Tests of seed viability have shown that seed must be
planted during the season following that of their maturity."
"The harvesting of the tung oil seeds offers no difficulty.f
When the fruits are mature they fall to the ground and may be
allowed to lie where they fall for several weeks. Usually in
Central Florida the dropping of the fruits occurs during the
Fig. 9.-Cross section of tung oil fruit. Courtesy B. F. Williamson.
dry months of October and November and they may be allowed
to lie on the ground until it is convenient to gather them. After
harvesting they should be stored in a dry place.
"In China the fruit is usually gathered before it is mature,
and the fruits are knocked off from the trees with bamboo
poles. They are then collected into heaps and allowed to fer-
ment until the husk can be easily removed. The harvesting
before maturity and the later fermentation are highly injurious
to the quality of the pressed oil and are not at all necessary.'
t E. L. Lord and B. F. Williamson, "The Tung Oil Tree," p. 33.
Fig, 10-Indivldual tung oil seed and fruit with portions of husk removed so as to show arrangement of
seed in fruit, Slightly reduced in sze, Courtesy Florida Agricultural Experiment Station,
Fig, I1-Young tung oil tree showing good crop of frolt, Courtesy B, F, Williimsom,
24 DEPARTMENT OF AGRICULTURE
COMPARATIVE ACRE YIELD OF OILS
The chief oil bearing crops in the United States are cotton,
peanuts and flax. The yield of oil that may be obtained from
any of these crops depends entirely upon the production of the
crop. A yield of a bale (500 pounds lint) of cotton per acre
means a production of 150 pounds of cottonseed oil. A peanut
crop that produces 25 bushels of peanuts per acre will give a
yield of 200 pounds of peanut oil. A good crop of flax averag-
ing 10 bushels an acre will produce a yield of 168 pounds of
linseed oil. A tung oil grove with 116 trees to the acre with
a production of 20 pounds of nuts to the tree will produce 788
pounds of oil an acre. This is equal to nearly five times that
produced by cotton or flax and four times that produced by
The above crops are all annuals, which means that they must
be planted each year. Tung oil trees, after they come into
bearing, will ordinarily continue to produce good crops for at
least twenty-five or thirty years.
PRICES OF TUNG OIL AND LINSEED OIL
Table No. 2 shows the high and low New York price of tung
oil by months since 1919 and Table No. 3 gives the same in-
formation regarding linseed oil.
TABLE 2-China Wood Oil*
(Per Lb, Bbls,, New York)
1919 1920 1921 1922 1923 192 1925 1926 1927 1928
H, L, H, L H L, H, L, H, L, H, L, H, L H L H L H, L
Jan, ............,28 $,22 ,26 $24 $.10i 1 $,I 12- $,I8A $18% I 21 $19 6 $18 $ $14 ,1i 1.15 $13, 1 $, 15
Feb. ...... .. 21 28 .24%f 10% 09 ,16 ,13% ,19 ,.18 ,19% .17% ,13 ,13 ,.1214 ,18% 17 ,17% ,16H
Mar. ......... 23 19 ,25 .2 ,1 ,9 ,15 1 ,18% ,181Y ,17 .14 ,13 ,124' 12 ,27 ,22 15 .14
April ..... ....21 .25 ,231 ,10% .9 ,14% ,13 ,40 ,28 ,17 ,14% ,13 ,13 ,124 % .11 ,35 ,3I ,16 ,14
May ............2 ,18 .24 ,22 ,15 ,09% 15 ,13% ,40 ,25 ,15 ,14 .13 .12% ,12 .11 .29 .195 ,15 .141
Juno ........ .23 ,2 ,23% 8 18% ,17 ,13% ,14% ,1 ,29 ,.25% ,14 .12% 414% ,12% .15% .15 .21 ,20 ,15% ,15
July ........... ,24 ,22 ,20 ,17% 16 ,12 14 .12 27 ,23 ,15 ,11% ,14 ,13 8 ,1 ,15 ,20% ,17 .15% ,15
Aug ......... 24 23 ,18 .17% ,16 .14 .13% .12 ,24 ,22 .15 .14 .13% ,13 ,18 .17 .18 .17 .17 .15
Sept. ......,24 .22 ,.18 .17% ,16% ,12 .13 .1254 .225 ,214 .15 .1 4% .13% .13 .19 .17% .18 ,16 .15 .148
Oct. ............ 23 .22% 18 .18 .16 ,14 .13 ,12 N .2385 ,21'% ,16% .15 ,13% .13 ,.17% .1 .16 .15
Nov., ....... 23 22 ,16 ,13 16 14 ,13 12 ,22 .21 .16 .15% ,.131 ,13 .16% .15 .15% .15Y
Dec 24 .22% ,13 .10% .15 ,131 14 .12, .25 .215. ,18 ,15% .131 ,13 ,15 13% N .15% .14|
American Paint Journal, October 19, 1928, p, 10,
TABLE 3-Linseed Oil, Spot'
Per Gal, Carlots, New York,
1919 i 1920 1921 1922 19819 2 8 1 1925 | 1928 1927 1928
H, L, H. L, H, L HH. L L H L, H. L, H, L I L H, L
Jan .. ........ ... 155 (1,45 1.77 1 77 If ,79, .7 .93 $ 92 ( .91 i 1,23 91,15 ,121 1 ,1 .109 0.12 I 9
Feb ............................ 1.45 1,45 1.77 1,77 .72 ,6 87 .7 ,98 .9 ,94 ,92 1,23 1,12 .113 ,1 ,18 107 100 ,098
arch ....................... 1.50 1.45 1,84 1,74 7 1 .8 77 1.10 ,96 ,94 90 1.20 104 ,112 ,107 ,105 .1 2 ,100 ,8
April ...................5...... 1,58 1 1,84 1,69 ,65 .57 .88 78 1,20 1,10 ,91 ,9 106 1,0 .111 ,108 ., 031,8 8 ,098
May ......... ................. 1,69 1,56 184 1 ,77 .92 .85 1.2 1.13 .95 .91 10 1,3 ,199 ,16 .112 ,109 ,13 ,102
June ............................ 1, 1. 1, 1,7 1,70 ,77 ,71 ,88 ,78 1.14 1,08 ,98 ,94 1,08 ,98 ,107 ,14 ,113 ,112 ,104 ,102
July ............................ 2,22 195 1,680 1.5 ,86 ,7 ,9 .8 1, .00 1,0 1 ,95 ,122 ,1 10 ,18 5 ,102 ,098
Aug .........................2... 2 2,22 125 1,5 22 ,78 ,7m 189 .85 1.02 .88 1,4 1,00 1.5 ,98, 123 ,111 ,108 ,105 099 ,095
Sept .......................... 2,22 1,88 1,22 1,12 .80 .1 ,90 ,87 ,92 ,88 1 .02 1,0 5 1,00,113 111 ,105 ,100 ,100 ,.95
Oct ........ .............. ......... 182 1,65 115 1 1, 0 .7 ( ,91 .8 ,95 .91 1.06 ,95 I .134 ,10 18 ,10 1 ,095
Nov, ............. ........... 1,77 1,72 1,02 ,77 .69 .9 .85 .92 ,92 11 1, ,129 .128 117 ,110 ,10 ,095
Dec ............................. 1,77 1.77 ,87 .77 ,69 ,90 ,87 ,92 ,90 1,15 5 129 ,121 110 ,102 .095 .094
American Paint Journal, October 19, 1928, p.10.
*Quotations in cents per pound beginning October, 1925, Note: 71 pounds in gallon,
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cured from American Paint Joirnal, October 19, 1928,
TUNG OIL, A NEW FLORIDA INDUSTRY
DECORTICATION AND PRESSING IN CHINA
The Chinese remove the husks entirely by hand. In some
cases they ferment the nuts by piling in large piles and allow-
ing them to heat, while in other cases the nuts are dropped
into hot water and taken out promptly. Both processes loosen
the husks so that they can easily be removed by hand.
When the seed are removed from the husk, they are crushed
by hand and heated in open pans. It is necessary to dry the
nuts thoroughly before pressing. After the crushed nuts have
been heated and dried, they are put into small sacks and
packed in a cavity hollowed out of a large log. A sack of
meats is put in the cavity, followed by a flat stone packed
next, which in turn is followed by another sack of meat and
another stone. This procedure is continued until the cavity
is filled. The cavity in the log is generally about twelve
inches wide and twenty-five to thirty inches long. When the
cavity is filled, wedges are driven in to produce the pressure
necessary to remove the oil.
DECORTICATION AND PRESSING IN FLORIDA
Machinery has been perfected and operated on a practical
scale for decortiCation-an pre~sing. The frii tiis allowed to
dry where it falls on the ground from the trees. The air-dried
fruit is placed in a hopper leading to the decortication machine
where the outer husk is removed. The whole mass is then
dropped on a screen that sifts out the fine dust and a suction
fan removes the hulls. The nuts are then carried to the crack-
ing mills, from where they finally go to the press. The ma-
chinery is entirely automatic from the time the fruit is dropped
into the hopper until the oil has been pressed out. The oil
comes out one part of the press and flows into storage tanks,
while the residue is carried by a conveyor to storage bins.
The Florida oil extracted by machinery is practically neutral
and of a light color, whereas the Chinese oil, due to the crude
method of handling, contains 5% to 8%/ free acid and is dark
in color. (See Fig. 15.) Mr. Arnold, the commercial attach
at Peking, states that one of the American presses does the
work of 90 to 100 Chinese. The Chinese also leave from 18%
to 22% of the oil in the residue, while the American press
leaves less than 6%.
Fig, 13,-Tung oil crushing !plant in Alachua County, Florida,
The first modern irUhiinn ol nt pvpr Pitahlik t ,, f' r tk PY,,,Eth, nl il,, ,ll Pr,,,,.n, ,, Wi Mllim,^,
TUNG OIL, A NEW FLORIDA INDUSTRY 29
USES OF TUNG OIL*
The Chinese use tung oil primarily as a waterproof covering
for wood and other materials which they wish to protect from
the weather. It is the principal paint oil of China, but it is
also used in medicine and as an ingredient of concrete. All
of the Chinese junks are oiled regularly with tung oil, and
calked with a mixture of tung oil, lime and chopped hemp.
Tung oil, or tung yu, after it has been heated for an hour, be-
comes white oil, or pei yu. Pei yu is added to lacquer varnish
as a drier, changing the color from black to brown, and making
the lacquer varnish dry much faster. Mixed with certain
mineral substances, and heated for a longer period, tung oil
is used by the Chinese for waterproofing silk. The oil is also
used as an ingredient for dressing leather, and for varnishing
furniture and floors. In the interior of China it is used to
some extent as an illuminant, but the light given by it is too
smoky and dirty to be satisfactory. When burned to a soot,
tung oil makes a finely divided carbon from which the Chinese
make India ink. The soot formed when the pomace is burned
is combined with the oil to make a paste for calking boats.
The oil is also used by the Chinese to some extent in making
soap and linoleum.
n- thTe-Uited States- tung oil is peculiarly valuable to the
paint and varnish industry. When combined with Southern
rosin it forms a substance known to the trade as rosin tung
ester or tunga resin. When combined with Southern rosin and
other substances into a varnish, it makes a spar varnish miuchi
more satisfactory than.copal varnish, which was formerly the
standard in varnishes. When this varnish is properly made
and applied a piece of wood covered'with it may be kept in
boiling water for fifteen minutes without either whitening or
softening the film.
When combined with cobalt, zinc, manganese, or lead, tung-
ates are formed. These substances are important ingredients
of paint driers. When combined with aluminum oxide it forms
aluminum tungate which is used, as a fire- and water-proofing
It is largely used in the manufacture of paints as well as
varnish, particularly for enamel, floor, deck and wall paints.
It may be used in place of linseed oil in the making of linoleum
and oil cloth. At the present time its use is increasing as fast
as the raw oil is available, and it is even now the most serious
commercial competitor of linseed oil. Besides the uses to which
E. L. Lord and B. F. Williamson, "The Tung Oil Tree," p. 42,
Fig, 14-Tung oil fruit ready for the crusher, Courtesy B, F, Williamson,
TUNG OIL, A NEW FLORIDA INDUSTRY 31
it is now put there are many more which would demand the
oil if there were only a sufficient quantity available in the
market. The peculiar properties of the oil make it highly im-
portant to the paint, varnish and allied industries that a con-
stantly increasing and regular supply be made available.
COMPOSITION OF THE OIL*
As before mentioned, the fruit of the tung oil tree usually
contains five or more seeds. Under average conditions these
seeds make up 53 to 65 percent of the total weight of the fruit.
When pressed whole without removing the seed coats (only
the outer husk having been removed) the seeds produce from
30 to 34 percent of oil. Due to the crude methods used, the
Chinese only get about 20 percent of oil from the seeds. There
is much misunderstanding in the discussion of the percentage
of oil obtained, due to the terms used. The fruit is made up of
two parts, the husks and the seeds. The seeds themselves are
also made up of two parts, the seed coats and the kernel. Before
the Chinese press the seeds they remove the husks and then
the seed coats, so that all that goes into the Chinese press is
When the seeds are properly handled in an Anderson ex-
peller, it is not necessary to remove the seed coats, in fact
it is an aid in pressing to have them remain attached to the
kernel. All that it is necessary to do is to crack the seeds
before they go to the expeller. American tung oil seeds proper-
ly handled in the Anderson expeller will produce 34 percent
As is well known to oil chemists, the oil as found in its
natural state in the oil cells of the seeds is practically color-
less and neutral in reaction, and when the oil is removed by
cold pressing it is light in color. By cold pressing it must not
be understood that the seeds are cold when pressed. In other
methods the seeds are heated to a high temperature some time
previous to pressing, while in "cold pressing" the cracked seeds
are only heated sufficiently to make the oil flow freely, and
this heat is only applied just before the seeds enter the press.
If, however, the seeds have been allowed to ferment in piles,
or the oil cells have been broken by heating some time before
they are to be pressed, or if they have been kept too moist, the
enzymes in the seeds begin to act upon the oil and the natural
pigments of the seeds. The results of this chemical activity
are a high acid number, a darkening in color, a consequent
lowering in quality, and a resulting limitation in the number
of uses to which the oil may be put. Due to the crude methods
E. L. Lord and B. F. Williamson, "The Tung Oil Tree," p. 38.
DEPARTMENT OF AGRICULTURE
in handling the oil in China, the best imported Chinese tung
oil which had been used as a standard by which other oils were
judged was not a prime tung oil. It was only when authorita-
tive American tung oil samples were produced that it was
understood how far the Chinese samples were from being prime
oil. Besides the impurity caused by the crude methods used
in pressing the oil, there is another factor to be considered.
It is an exceptional sample of tung oil that gets out of the
hands of the Chinese without being adulterated to some degree
with soya, stillingia, sesame, peanut, or some other low-grade
According to the investigations so far reported tung oil is
composed principally of the glyceride bf elaeomargaric acid
or elaeostearic acid as it is sometimes called. Elaeomargaric
acid has the composition of Cs,,H202, and is a stereoismeride of
linoleic acid. Besides the glyceride of elaeomargaric acid, tung
oil also contains 10 percent or less of the glyceride of oleic
acid and 2 to 3 percent of saturated fatty acids.
The peculiar properties of tung oil are due to the elaeomar-
garic acid. Pure tung oil is especially noteworthy in that it
has (1) a high specific gravity (only castor oil excels it); (2)
a refractive index higher than that of any other known oil;
(3) exceptional drying power (it has much better drying prop-
erties than linseed oil) ; (4) it has a very high viscosity; (5)
when heated to 250 degrees C. or over for a few minutes and
then cooled it solidifies, forming a firm jelly that crumbles
readily and is not sticky.
The standard test for tung oil as published by the American
Society for Testing Materials and to which all tung oil should
conform is as follows:
TUNG OIL FROM CHINA
Spec. Gravity at 15.5 degrees C ................................ 0.943 0.939
Acid Number (alcohol-benzol) . ....... -.. .. ........- 7.0
Saponification Number ..................... ........ ........... 195.0 190.0
Unsaponifiable Matter, percent .................. .............. .76
Refractive Index at 25 degrees C ............................ 1.520 1.515
Iodine Num ber (W ijs) --........... ...................... . ......... 163.0
A. S. T. M heating test, minutes ........................ ... 12.0......
ANALYSIS PRESSED FLORIDA TUNG OIL"
Appearance-Almost colorless, faint amber tinge.
Odor-Faint, but characteristic tung oil odor.
Specific Gravity at 15.5 degrees C. ............. ................... ........ .9417
Acid number ........ ................................... .. .1
Iodine number (Hubl) ................................ ...... -.. ....... .. 170.1
Saponification num ber ................-........................ 192.4
Unsaponifiable matter ......... ........... ............... ....... .23%
Browne heat test (minutes) --------_- ...................... ............ 9-10
Scientific Section, American Paint and Varnish Manufacturers'
Association, Washington, D. C.
TUNG OIL, A NEW FLORIDA INDUSTRY 33
TUNG OIL POMACE
The pomace or residue from the oil mill has considerable
value as a fertilizer. The fertilizer analysis of the material is
about as follows:
A m m onia ............................................. 6.42 percent
Phosphate .......... ......... ......... ..... 3.78 percent
P otash .................................................. 1.28 percent
The value per ton, with present prices of fertilizing elements,
would be about $35 to $40. So far as is known at the present
time, this material can be used on almost any crop to good
Some people have questioned the ability of Florida to pro-
duce tung oil in competition with cheap Chinese labor. Julian
Arnold, the American commercial representative at Peking,
laughs at this idea. He says that Chinese can be employed at
15 cents per day, but one of the American presses will do the
work of 90 to 100 Chinese. Transportation in China, he states,
is on human backs and costs five to seven times as much as
transportation in this country, even with our expensive labor
and high freight rates. Manufacturing in Florida will be done
with machinery from the time the nuts are delivered to the
press. Cultivation in this country is also done by machinery.
Three small tractors will cultivate 100 acres in a single day.
Tung oil production, compared with linseed, probably will be
several hundred percent greater per acre. Whereas linseed
must be planted every year, one is led to believe these trees
will show a bearing age of 25 to 30 years.
Looking at this matter from every standpoint, it would ap-
pear that here is an industry where over-production is a long
way off, where demand exceeds supply, and where the product
is an essential in an established industry already developed
and rapidly increasing.
Readers of this bulletin are referred to the Florida Agricul-
tural Experiment Station, Gainesville, Fla., for the latest ex-
perimental data and information on tung oil. Anyone inter-
ested in this subject should by all means write to the Experi-
ment Station for Bulletin No. 171, "The Tung-Oil Tree in
Florida," which contains much valuable information on the
Fig. 15.-Representative samples of Florida and Chinese tung oil. Florida
tung oil is neutral and light colored. Chinese tung oil is dark and contains
seven percent free acid. Courtesy B. F. Williamson.