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
_Stiffening and Proofing Process._--Before proceeding to discuss the
stiffening and proofing of hat forms or "bodies," it will be well to
point out that it was in thoroughly grasping the importance of a
rational and scientific method of carrying out this process that
Continental hat manufacturers had been able to steal a march upon their
English rivals in competition as to a special kind of hat which sold
well on the Continent. There are, or ought to be, three aims in the
process of proofing and stiffening, all the three being of equal
importance. These are: first, to waterproof the hat-forms; second, to
stiffen them at the same time and by the same process; and the third,
the one the importance of which I think English hat manufacturers have
frequently overlooked, at least in the past, is to so proof and stiffen
the hat-forms as to leave them in a suitable condition for the
subsequent dyeing process. In proofing the felt, the fibres become
varnished over with a kind of glaze which is insoluble in water, and
this varnish or proof is but imperfectly removed from the ends of the
fibres on the upper surface of the felt. The consequence is a too slight
penetration of the dyestuff into the inner pores of the fibres; indeed,
in the logwood black dyeing of such proofed felt a great deal of the
colour becomes precipitated on the outside of the fibres--a kind of
process of "smudging-on" of a black pigment taking place. The subsequent
"greening" of the black hats after a short period of wear is simply due
to the ease with which such badly fixed dye rubs off, washes off, or
wears off, the brownish or yellowish substratum which gradually comes to
light, causing a greenish shade to at length appear. If we examine under
the microscope a pure unproofed fur fibre, its characteristic structure
is quite visible. Examination of an unproofed fibre dyed with logwood
black shows again the same characteristic structure with the dye inside
the fibre, colouring it a beautiful bluish-grey tint, the inner cellular
markings being black. A proofed fur fibre, on the other hand, when
examined under the microscope, is seen to be covered with a kind of
translucent glaze, which completely envelops it, and prevents the
beautiful markings showing the scaly structure of the fibre from being
seen. Finally, if we examine microscopically a proofed fibre which has
been dyed, or which we have attempted to dye, with logwood black, we
find that the fibre presents an appearance similar to that of rope which
has been drawn through some black pigment or black mud, and then dried.
It is quite plain that no lustrous appearance or good "finish" can be
expected from such material. Now how did the Continental hat
manufacturers achieve their success, both as regards dyeing either with
logwood black or with coal-tar colours, and also getting a high degree
of "finish"? They attained their object by rubbing the proofing varnish
on the inside of the hat bodies, in some cases first protecting the
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