BEATING 87
Modern beaters are designed to circulate in the quickest possible time, and
at the same time to possess a large bed-plate area in order that a greater amount
of work may be done during one circulation of the stuff This is done by
having a very wide bed-plate, or more often by having a series of bed-plates.
There is also a tendency at the present time to use lighter rolls, as it is claimed,
apparently with some authority, that the work can be just as well done with
lighter rolls and less power.
BEATING
Among all the various processes which are used in the manufacture of
paper, none has aroused so much" controversy and discussion as beating.
'What takes place in the beater?' is still a question that has not yet been
answered to the satisfaction of the chemist, the engineer, and last, but not
least, the paper-maker.
• We propose, however, as paper-makers, to offer an explanation as the result
of our experience, aided by the results of the investigations of those who have
of late years devoted so much time and careful thought to the subject.
At die outset we propose to divide the subject into two phases, 'free* beating
and 'wet' beating.
By 'free' beating we define those processes where such fibres as mechanic a
wood, esparto, straw, etc.—very short and poor in themselves—require no
more than to be separated from clumps or clusters, and are sent io. almost, if
not quite, their original forms to the staff chest
The term 'free' we regard as denoting the result of this elementary 'beating/
The fibres, when passing over the wet end of the machine, part from the water,
in which they float, easily and freely.
The power required for treatment can be calculated,, and special engines, such
as the refining engine, can be used to achieve successful and satisfactory results.
The action of these special engines is not, in the true sense of the word,
'beating*, although there is no doubt that some actual beating can, and does,
take place when the fibre is of such a form and structure as can stand it. This
class of beating suffices for newsprint and other printing papers, and also for
all those papers made from esparto with a small percentage of chemical wood.
It is when we come to deal with papers of a better class, such as writings, banks,
ledgers, cartridges, tissues, and 'Manillas', and, in feet, most papers that require
to be water-marked, or to have strength, transparency, or any other special
feature, that the second phase of beating becomes of paramount importance.
Then, in various degrees, the stuff must be what has been called by the older
paper-makers 'beaten wet1. We by no means dismiss the first class of beating