e._ leave less free nitric acid in their
mixture; but he prefers his own method, and thinks it answers best for
the promotion of felting. The treated fur he gave me was turned yellow
with the nitric acid, in parts brown, and here and there the hairs were
slightly matted with the acid. In my opinion the fur must suffer from
such unequal treatment with such strong acid, and in the final process
of finishing I should not be surprised if difficulty were found in
getting a high degree of lustre and finish upon hairs thus roughened or
partially disintegrated. Figs. 11 and 12 respectively illustrate fur
fibres from different parts of the same hare before and after the
treatment. In examining one of these fibres from the side of a hare, you
see what the cause of this roughness is, and what is also the cause of
the difficulty in giving a polish or finish. The free edges are
partially disintegrated, etched as it were, besides being caused to
stand out. A weaker acid ought to be used, or more mercury and less
acid. As we shall afterwards see, another dangerous agent, if not
carefully used, is bichrome (bichromate of potassium), which is also
liable to roughen and injure the fibre, and thus interfere with the
final production of a good finish.
Pages:
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36