266
CORE
TESTING
METHOD
[Vol. XXIV, Part IV,
temperature of the various bowls and the concentration of soap and soda ash are
always maintained steady during the entire process of scouring. The wool is moved
in the scouring liquor steadily and slowly by mechanical rakes or forks. It is passed
between squeeze rollers which remove the dust and dirty liquor before going from
one bowl to the next and finally coming out of the rinse bowl loose and open with
a good deal of water squeezed out. The sand and other heavy dirt are allowed to
settle on the bottom as the cleansed fibres move along just under the surface of the
scouring liquor. After the sample is thus treated it is ready for drying.
In core testing laboratories the devices used for imitating the above action
vary in different laboratories but the basic idea is to open out the fibres as much
as possible to facilitate a better action of the scouring fluids. Any standard of
scouring fluid or the agitation of wool in the scouring bowls used in a wool testing
laboratory is followed without change for all wool samples received for testing.
Drying and blending. After scouring and rinsing the wool sample, it is generally
spun in a centrifuge in order to remove the bulk of the moisture after which the
sample is placed in a steam heated dryer to remove the remaining moisture. After
thorough drying, the impurities such as small pieces of paper twine, vegetable
matter, paint, etc. that still remain in the sample are removed by hand. The
weight of the dried sample is recorded on bone dry basis by conditioning it in an
oven for six hours at 110°C.
Ash test. This test is conducted to determine the amount of sand and dirt
remaining in the wool. A duplicate subsample from the scoured wool is
heated in a crucible over a burner until all organic fumes have been
driven off and the wool has been completely converted to a charred mass. This
charred material is then heated in an electric muffle furnace at 600°C until the car-
bon has been removed and only a light coloured ash is left. The ash along with the
container is conditioned in an oven under standard conditions and the weight
recorded.
Test for determining vegetable matter. A duplicate subsample from the scoured
wool is kept in a glass beaker and is then covered with a hot 10 per cent solution
of sodium hydroxide until the beaker is half full. The solution and the wool are
stirred until all the wool is dissolved. If all the wool does not dissolve it may be
boiled until it is completely dissolved. The vegetable matter being insoluble in
alkaline solution will stand out suspended. The vegetable matter so isolated is
filtered off with the help of a 40-mesh sieve. A wash with five per cent solution
of sodium hypochlorite or ' clorax ' is given to remove the last remnants of wool.
It is then washed with water, dried and weighed. The residual vegetable matter
is then placed in a weighed beaker and conditioned for six hours under standard
conditions after which it is weighed and the weight recorded.
Determination of grease and soap left in wool. For this test a subsample is
placed in Soxhlet Extractor containing alcohol. Approximately 30 c.c. of 95 per
cent alcohol is added to a weighed extraction flask. To the extraction condenser
is also added alcohol until it covers the wool sample to a point just below the over-
flow strip. The alcohol is evaporated and condensed for one hour from the time the
overflow strip empties the condenser for the first time. Care is taken to see that the
flask is not allowed to boil dry at any time. After the alcohol has run through for