The Chemistry of Hat Manufacturing: Lectures Delivered Before the Hat Manufacturers' AssociationSmith, Watson
Science
The Chemistry of Hat Manufacturing: Lectures Delivered Before the Hat Manufacturers' Association
Smith, Watson
Hats
of free fatty matter,
of course perfectly equally distributed, and not due to irregular
saponification. On the average the soap solution for scouring wool may
contain about 6-1/2 oz. of soap to the gallon of water. In order to
increase the cleansing powers of the soap solution, some ammonia may be
added to it. However, if soap is used for wool-scouring, one thing must
be borne in mind, namely, that the water used must not be hard, for if
insoluble lime and magnesia soaps are formed and precipitated on the
fibre, the scouring will have removed one evil, but replaced it by
another. The principal scouring material used is one of the various
forms of commercial carbonate of soda, either alone or in conjunction
with soap. Whatever be the form or name under which the carbonate of
soda is sold, it must be free from hydrate of soda, _i.e._ caustic soda,
or, as it is also termed, "causticity." By using this carbonate of soda
you may dispense with soap, and so be able, even with a hard or
calcareous water, to do your wool-scouring without anything like the ill
effects that follow the use of soap and calcareous water. The carbonate
of soda solutions ought not to exceed the specific gravity of 1 deg. to 2 deg.
Twaddell (1-1/2 to 3 oz. avoird. per gallon of water). The safest plan
is to work with as considerable a degree of dilution and as low a
temperature as are consistent with fetching the dirt and grease off. The
scouring of loose wool, as we may now readily discern, divides itself
into three stages: 1st, the stage in which those "yolk" or "suint"
constituents soluble in water, are removed by steeping and washing in
water. This operation is generally carried out by the wool-grower
himself, for he desires to sell wool, and not wool plus "yolk" or
"suint," and thus he saves himself considerable cost in transport. The
water used in this process should not be at a higher temperature than
113 deg. F., and the apparatus ought to be provided with an agitator; 2nd,
the cleansing or scouring proper, with a weak alkaline solution; 3rd,
the rinsing or final washing in water.
Thus far we have proceeded along the same lines as the woollen
manufacturer, but now we must deviate from that course, for he requires
softness and delicacy for special purposes, for spinning and weaving,
etc.; but the felt manufacturer, and especially the manufacturer of felt
for felt hats, requires to sacrifice some of this softness and delicacy
in favour of greater felting powers, which can only be obtained by
raising the scales of the fibres by means of a suitable process, such
as treatment with acids. This process is one which is by no means
unfavourable to the dyeing capacities of the wool; on the whole it is
decidedly favourable.
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