CHAPTER I
FIBROUS MATERIALS USED IN THE MANUFACTURE OF
PAPER
A SHEET of paper consists chiefly of a collection of vegetable fibres, of different
lengths and sizes, twisted and interlaced with each other, and finally squeezed
together, to make a sheet or web with a surface suitable for writing and
printing. - .
The strength of paper depends to a great extent, though not entirely, on
the length and strength of the individual fibres which go to make it, and also
on the character of the fibres themselves.
The quality, or kind of paper made, depends on the nature of the fibres. As
the fibres from different plants are in themselves different in structure, length and
purity, it is necessary, first of all, to have some knowledge of the nature and
appearance of the various fibres.
Fibres are the 'bones' of all plants. Just as the bones of animals are the frame-
work on which are built up the living bodies, so are the fibrous elements of
plants the supporting framework of the living plant.
Fibres from plants are the raw material of the paper-maker, and to obtain
these fibres free from the protoplasm, or living juices and matters which are
contained in and surround the fibres, is the first work he has to undertake. When
so obtained, the fibres are termed 'cellulose'.
Fibres are too small to be seen distinctly with the naked eye, but the
characteristics can be readily distinguished and examined with the aid of a
microscope.
We shall concern ourselves chiefly with the five principal materials illus-
trated: Cotton, Linen, Esparto, Wood and Straw.
With the single exception of Cotton, all these fibrous materials are made
up of varying proportions of cellulose and lignin, together with rosin, silica and
plant juices, and it is this substance, cellulose, to which they have to be reduced
in the pulp or paper mill.
Cellulose, as we know it in the mill, is a white, fibrous substance, having the
chemical formula CeHioOs, which means that six atoms of carbon are combined
with ten atoms of hydrogen and five atoms of oxygen, to form one molecule
of cellulose.