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Appendix






=Testing Textile Fabrics.= This is an age of adulteration, and next to
food there is probably no commodity that is adulterated as much as the
clothing we wear. Large purchasers of textile fabrics and various
administrative bodies, such as army clothing departments, railway
companies, etc., have adopted definite specifications to ensure having
good material and workmanship. Before the fabrics are accepted they
are examined carefully by certain tests to see if they meet the
requirements. Wholesale and retail merchants insist on various
conditions when purchasing fabrics in order to conform to the
increasing needs of the public. Hence every manufacturer, buyer, or
dealer in fabrics should be familiar with the tests used to determine
the quality of goods he is about to buy.

The tests used are as follows:

1. Identification of the style of weaving.

2. Testing the breaking strength and the elasticity by the dynamometer.

3. Determining the "count" of warp and filling.

4. Determining the shrinkage.

5. Testing the constituents of warp and of filling.

6. Testing the finish and dressing materials.

7. Testing the fastness of the dye.

=Directions for Determining the Style of Weave.= In examining a
fabric for the weave it is first necessary to determine the direction
of the warp and filling threads. This is a very simple matter in a
great many fabrics that have a selvedge--the warp must be parallel to
the selvedge.

In fabrics that have been fulled, raised, and cropped, as buckskin,
flannel, etc., the direction of the nap will indicate the direction of
the warp, since the nap runs in this direction.

In the case of fabrics with doubled and single threads, the doubled
threads are always found in the warp.

In fabrics composed of cotton and woolen threads running in different
directions, the cotton yarn usually forms the warp and the woolen yarn
the filling. Then again the warp threads of all fabrics are more
tightly twisted than the filling threads, and are separated at more
regular intervals.

Sometimes in stiffened or starched goods threads running in only one
direction can be seen. In this case they are the warp threads.

If one set of threads appears stiffer and straighter than the other,
the former may be regarded as warp, while the rough and crooked
threads are the filling. The yarn also gives one a hint, since the
better, longer, and higher number material constitutes the warp, while
the thicker yarn the filling.

The direction of the twist of the thread is conclusive; if one set has
a strong right twist and the other a left twist the first is the warp.

After determining the direction of the warp and filling, the next
point is to determine the interlacing of the warp and filling
threads--the weave. This may be done by inspection or by means of a
pick-glass and needle. The weave may be plotted on design paper
(plotting paper), the projecting warp threads being indicated by
filling up the corresponding square, and leaving those referring to
the filling threads blank. In this way the weaving pattern of the
sample is obtained, and serves as a guide to the weaver in making the
fabric, as well as for the preparation of the pattern cards for the
Jacquard loom.

=Testing the Strength and Elasticity of a Fabric.= The old-fashioned
plan of testing cloth by tearing it by the hand is unreliable, because
tearing frequently requires only a certain skilled knack whereby the
best material can be pulled in two. In this way an experienced man may
tell good from bad cloth, but he cannot determine slight differences
in quality, because he has exerted his strength so often that his
capacity to distinguish the actual force has disappeared.

The best means of determining the strength of a fabric is by means of
a mechanical dynamometer,[19] which expresses the tensile strength of
the fabric in terms of weight. The machine is very useful to the
manufacturer because it enables him to compare accurately his various
products with those of his competitors. The value of these tests is
sufficiently proved by the fact that all army clothing departments,
etc., require their supplies of cloth, etc., to pass a definite test
for strength.

Breaking tests also afford the most certain proof to bleachers of
cotton and linen goods as to whether the bleaching has burned or
weakened the goods. The same test will quickly determine whether a
fabric has been improperly treated in the laundry.

=Determining the Count of Warp and Filling Threads.= Every fabric must
contain a certain count of warp and filling threads--a definite number
within a certain space for each strength of yarn employed. A fabric is
not up to the standard of density when less than the requisite number
of warp or filling threads per inch is found. For example, if a buyer
was told that a fabric is 80 square, that is, eighty warp threads and
eighty filling threads to the inch, and on examination found only 72
square, he would immediately reject the goods.

The count of warp and filling is determined by means of a
pick-glass--a small mounted magnifying glass--the base of which
contains an opening of one-half inch by one quarter inch, or one
quarter inch by one quarter inch. If the pick-glass is placed on the
fabric the number of warp and filling threads may be counted, and the
result multiplied by either two or four, so as to give the number of
threads to the inch. For example, if I count twenty picks and twenty
threads on a one quarter-inch edge, there are eighty picks and eighty
threads to the inch. A more accurate result can be obtained by using a
pick-glass with a one-inch opening.

=Determination of Shrinkage.= A very important factor in the value of
a fabric is the shrinkage. The extent of this may be determined by
pouring hot water over a sample of about twelve by twenty inches, and
leaving the fabric immersed over night, then drying it at a moderate
temperature without stretching. The difference in length gives the
shrinkage, which is usually expressed in percentage.

=Determination of Weight.= Buyers and sellers of dry goods, when
traveling, are anxious to determine the weight of fabrics they
examine. This may be done by means of small pocket balances so
constructed as to give the number of ounces to the yard of a fabric.

=Testing the Constituents of the Warp and Filling.= Take a sample
piece of the cloth to be examined--the piece must be large enough to
contain specimens of all the different kinds of yarn present in the
material--and separate all the filling and warp threads. Be sure that
all double threads are untwisted.

=Combustion Test; Test for Vegetable and Animal Fibers.= Burn
separately a sample of the untwisted warp and filling threads. If one
or both burn quickly without a greasy odor, they are vegetable fibers,
cotton or linen. If one or both burn slowly and give off a greasy
odor, they are animal fibers, wool or silk. This test is not
conclusive, and further chemical examination--acid test--must be made
to ascertain whether wool is pure or mixed with cotton.

=Acid Test.= The vegetable fibers, cotton and linen, are distinguished
from those of animal origin by their behavior in the presence of
acids and alkalies. The vegetable are insoluble when boiled with a 4
per cent sodium hydrate solution, but readily clear or carbonize when
saturated with a 3 per cent sulphuric acid solution and allowed to dry
at a high temperature in a hot closet. Wool on the other hand is not
affected by the action of weak sulphuric acid.

=Cotton Distinguished from Linen.= If the fibers are vegetable, cotton
may be distinguished from linen by staining the fibers with fuchsine.
If the fibers turn red, and this coloration disappears on the addition
of ammonia, they are cotton, if the red color remains the fibers are
linen. Whenever cotton yarn is used to adulterate other fabrics, it
wears shabby and loses its brightness. When it is used to adulterate
linen, it becomes fuzzy through wear. One may detect it in linen by
rolling the goods between thumb and finger. Linen is a heavier fabric,
and wrinkles much more readily than cotton. It wears better, and has
an exquisite freshness that is not noticed in cotton fabrics.

=Silk Distinguished from Wool.= Place the fabric or threads containing
animal fibers in cold, concentrated hydrochloric acid. If silk is
present it will dissolve, while wool merely swells.

=Artificial Silk from Silk.= On account of the low value of the
artificial and the high value of genuine silk, there is a tendency to
offer the artificial instead of the pure article. Test: When
artificial silk is boiled in 4 per cent potassium hydrate solution it
produces a yellow solution, while pure silk gives a colorless
solution.

A common test is to put the artificial silk in water, where it will
pull apart as though rotten; or to take out one strand of the silk,
hold it between the finger and thumb of each hand and wet the middle
of the strand with the tongue, when it will pull apart as though
rotten.

Artificial silk is inferior in strength and elasticity to pure silk.
Then again it is lacking in the crackling feeling noticed in handling
the genuine article.

=Test for Shoddy.= It is no easy matter to detect shoddy in woolen
fabrics; the color of the shoddy threads is the best evidence. Many
parcels of rags are of one single color, but for the most part they
are made of various colored wools; therefore, if on examination of a
fabric with a magnifying glass a yarn of any particular color is found
to contain a number of individual fibers of glaring colors, the
presence of shoddy can be assumed with certainty.

Woolen goods containing cotton are seldom made from natural wool.
Shoddy yarns, especially in winter goods, are found in the
under-filling at the reverse side of the cloth, as thick, tightly
twisted yarns, curlier than those from the pure wool.

=Determination of the Dressing.= During the various operations of
washing, bleaching, etc., the goods lose in weight, and to make up
this deficit a moderate amount of dressing or loading is employed.
Dressing is not regarded as an adulteration, but as an embellishment.

Various dressing materials are used, such as starch, flour, mineral
matters, to give the goods stiffness and feel on one hand, and on the
other to conceal defects in the cloth, and to give a solid appearance
to goods of open texture. The mineral substances used serve chiefly
for filling and weighting, and necessitate the employment of a certain
quantity of starch, etc. In order that the latter may not render the
cloth too stiff and hard, further additions of some emollient, such as
glycerine, oils, etc., are necessary.

When a fabric filled in this manner is placed in water and rubbed
between the hands, the dressing is removed, and the quantity employed
can be easily determined.

By holding fabrics before the light dressing will be recognized, and
such goods, if rubbed between the fingers, will lose their stiffness.
Loading is revealed by the production of dust on rubbing, and by the
aid of the magnifying glass it can be easily ascertained whether the
covering or dressing is merely superficial or penetrates into the
substance of the fabric.

=The tests of permanence of dyes on fabrics are as follows:=

=Washing Fastness.= Fabrics should stand mechanical friction as well
as the action of soap liquor and the temperature of the washing
operation. In order to test the fabric for fastness a piece should be
placed in a soap solution similar to that used in the ordinary
household, and heated to 131 degrees F. The treatment should be
repeated several times. If the color fails to run it is fast to
washing.

=Fastness Under Friction.= Stockings, hosiery yarns, corset stuffs,
and all fabrics intended to be worn next to the skin must be
permanent under friction, and must not rub off, stain, or run, that
is, the dyed materials must not give off their color when worn next to
the human epidermis (skin), or in close contact with colored articles
of clothing, as in the case of underwear.

The simplest test is to rub the fabric or yarn on white unstarched
cotton fabric. In comparing the fastness of two fabrics it is
necessary to have the rubbing equal in all cases.

=Resistance to Perspiration.= With fabrics coming in contact with the
human skin it is necessary in addition to fastness under friction that
they should withstand the excretions of the body. The acids of
perspiration (acetic, formic, and butyric) often become so
concentrated that they act on the fiber of the fabric.

In order to test the fabric for resistance, place the sample in a bath
of 30 per cent dilute acetic acid (one teaspoonful to a quart of
water) warmed to the temperature of the body, 98.6 degrees F. The
sample should be dipped a number of times, and then dried without
rinsing between parchment paper.

=Fastness against Rain.= Silk and woolen materials for umbrella
making, raincoats, etc., are expected to be rainproof. These fabrics
are tested by plaiting with undyed yarns and left to stand all night
in cold water.

=Resistance to Street Mud and Dust.= Ladies' dress goods are expected
to withstand the action of mud and dust. In order to test a fabric for
this resistance the sample should be moistened with lime and water
(10 per cent solution), dried, and brushed. Or sprinkle with a 10 per
cent solution of soda, drying, brushing, and noting any changes in
color.

=Fastness to Weather, Light, and Air.= Various people have attempted
to set up standard degrees of fastness--for every shade of color is
affected by the action of sun, light, and air--and as a result fabrics
that remain without appreciable alteration for a month of exposure to
direct summer sunlight are classified as "fast," and those undergoing
slight appreciable change under the same conditions as "fairly fast."
"Moderately fast" colors are those altering considerably in fourteen
days; and those more or less completely faded in the same time
(fourteen days) are designated as "fleeting."

=Directions for testing fastness of Color in Sunlight.= Cover one end
of the sample of cloth with a piece of cardboard. Expose the fabric to
the sunlight for a number of days and examine the cloth each day in
the dark and notice whether the part exposed has changed in color when
compared with the part covered. Count the number of days it has taken
the sunlight to change the color.

Brown in woolen materials is likely to fade. Brown holds
its color in all gingham materials.

Dark blue is an excellent color for woolens and
ginghams. Light blues on the other hand usually change.

Black, gray, and black with white. These colors are very
satisfactory for woolen materials.

Black is not a color which wears very well with cotton
fabrics, as it shows the starch (sizing) and often
fades.

Red is an excellent color for all woolen materials. It
looks attractive and wears well.

Red is a very poor color for cotton. It loses its
brilliancy and frequent washing spoils it.

A deep pink is an excellent color for all ginghams for
it fades evenly and leaves a pretty shade.

Green is a poor color for both cotton and woolen
materials unless it is high priced.

Lavender fades more than any other color in textiles.





Next: History Of Textiles

Previous: Substitutes For Cotton



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