BEATING LINEN 101
In general, papers made from cotton fibres are more bulky, and handle
better than those made from any other fibre, or mixture of fibres, and it is this
quality which renders them very valuable, and in fact indispensable, for papers
which are required to bulk well.
Linen.—The value of the linen fibre to the paper-maker lies in its great
capacity for fibrillation. Its thick walls are fundamentally striated and its
canal is small in comparison with its bulk. Obviously it will require heavy
beating to disintegrate it. Unless the bars and plates are very sharp it splits
more readily than it cuts. For this reason, compared to cotton, its use is rather
limited except for special papers. It is seldom, if ever, run as a whole furnish,
but it gives, even in a small proportion,^ certain TeeF to paper which can
be readily distinguished by a skilled paper-maker. This feel is very difficult to
describe, but may be attributed to the cool, glossy surface of the fibre.
It does not readily take a good water-mark unless highly fibrillated, but in
the latter case the binding effect of its fibrillae gives great strength and hardness.
For a good ledger paper, up to 25 per cent may be used with advantage. It
must be beaten separately, and not in a beater with the other components of
the furnish, as the heavy treatment it requires would destroy the strength of
these components to a greater extent than the linen could compensate. Perhaps
neglect of this very obvious precaution is the reason why many paper-makers
assert that linen has less strength as a paper-making material than cotton.
A blend of chemical wood with 10 per cent of linen gives a paper of sur-
prisingly good strength and hardness, and—judging from the frequency of this
combination in many papers we have examined—it is a very popular one.
Although an all-linen paper is very seldom met with, in thin papers the
proportion of linen may be greatly increased with excellent results. With
about 8 to 12 hours' beating with dull tackle and high concentration of stuff
in the beater, a furnish of 75 per cent linen will produce a pulp that will work
extremely wet on a 66-mesh wire at 7 Ib. in Large Post and give a very strong
paper.
The hardness of the linen fibre renders it more immune from serious damage
in the beater than is the case with cotton; for while a careless manipulation
of the roll during the first hour or two in the beater will ruin a furnish of cotton,
the linen seems capable of standing the weight of the roll bettor, and is not
so likely to be spoilt unless all the tackle is very sharp.
There are various reasons for the linen fibre bong more easily fibrilkted
in the beater than cotton. In the first place, as we have already said, the structure
of the fibre lends itself to longitudinal splitting, and in addition the fibre con-
tains knots or bulbous swellings which split and become fibrilkted by the
weight of the roll