December, 1954 ] G. S. MAHAL AND S. JAYARAMAN 267
about five to six treatments, the extraction condenser is separated from the flask
and the excess alcohol in the flask is evaporated from the residual grease. The
extraction flask and grease are weighed after conditioning the extraction flask
for six hours under standard conditions.
CALCULATION OF RESULTS
When all the laboratory processes are completed, the clean weight of pure wool
fibre without any impurities is known. However, what is commercially known
as ' clean wool ' always contains a certain percentage of extraneous matter. In order
to bring the laboratory calculation of shrinkage in line with commercial practice,
the clean weight of the wool sample is calculated as containing certain standard
allowances for impurities. The standard allowances for non-wool components in
commercial scoured wool are 12 per cent moisture, 1.5 per cent ash, and 0.5 per
cent extractives. In other words, the standard clean weight of the sample is cal-
culated so as to contain an added allowance of 14 per cent non-wool materials. As
an example, if the clean weight of pure wool fibre is 43 grams then the clean weight
of the sample is calculated as 43 × 100/86 or 50 grams.
CONCLUSION
The core test method is considered to be an accurate and practical method so
far devised for determining shrinkage in wool. Though the procedure and technique
of applying this test to carpet wools will essentially be the same, there are some
differences as a consequence of the difference in the density, gross weight and dimen-
sion of the bales. According to the degree of compression, bales may be divided
into low density, medium density and high density. If the stock is 20 lb. or less
per cubic foot the bale is said to be low density bale while a medium density bale
measures 20 to 30 lb. per cubic foot. If it contains more than 30 lb. per cubic foot
it is considered a high density bale. The slight differences arise as a result of the
low density bales or bags tending to expand during the insertion of the coring tube
which consequently causes locks of wool to be pushed aside by the cylinder rather
than being cored and forced into the sampling tube. All these aspects shall have
to be considered in deciding the correct method of sampling carpet wools both in
designing the size of the tube and the actual method of sampling.
According to Lyons (loc. cit.) the bulk of carpet wools exported to the U.S.A.
are packed in medium density bales, and these are reported to be the easiest to
core whether in the grease or dry scoured condition. The author further reports
that it may be effectively cored by penetrating the cylinder slowly and sinking
the full length of the cylinder into it. It has been suggested that in the sampling
of carpet wools not less than 15 per cent of the bales uniformly distributed through-
out the lot are cored. The laboratory technique for subsequent analysis of the
wool sample is essentially the same.
Although the practical utility of the core testing method has not been fully
utilised in the other wool producing countries of the world, it may prove a useful
application in solving the wool marketing problems in India. Before the method
is taken up, it will have to be determined whether it is applicable to carpet wools
with the same efficacy as it has proved in the U. S. A. for fine wools and cross-bred
104 AR/54.
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