90 MODERN PAPER-MAKING
misleading and erroneous. It has been presumed that stuff must be wet or
hydrated before it is in that condition which makes the strongest paper.
Mr. Strachan, in our opinion, conclusively proves that 'hydration' is
merely the sign that the stuff has attained that condition, and our personal experi-
ence in beating entirely coincides with his proof. He shows that when the
fibres are subdivided into Jibrillce and partly crushed into very fine particles,
. more water adheres to their surfaces, or that the mixture of stuff and water
has become more intimate; each minute particle of stuff has its superficial area
increased by subdivision, and that additional surface area is covered by a film of
water. Therefore, the fact that extra water has been attracted to the stuff is
not the reason why the paper will be stronger, for the strength is caused by
the fibres being 'fibrillated9, and this, we think, is the proper word to describe
the condition.
It can certainly never be asserted that water adds strength to fibres; therefore
it must be that they gain strength by being fibrillated.
Now let us describe what does actually take place in the beater from this
standpoint. We will presume that we have got a hollander furnished with
linen fibres. This stuff has been boiled and gas-bleached to remove all sliive.
We may presume that in these processes the fibres have been thoroughly
saturated with water. Indeed, it is inconceivable that thorough saturation has
not taken- place. Every pore, canal and surface of each individual fibre has
its full quota of water; yet it cannot be said to be hydrated in the true meaning
of the word.
To return to the beater. We know that if we simply clear the fibres of
knots, etc., and run them over the wire, the sheet will look raw and cloudy,
and the fibres will be too cumbrous to felt with each other, and may be easily
pulled apart. The dandy roll will be unable to make a proper impression on
the sheet. Therefore we have to 'beat9 the linen fibres—and 'linen takes a
lot of hammering', as every beaterman knows—in other words, we must
have the fibres well jibrillated. If our beater bars are too sharp we have great
difficulty in fibrillating the fibres; instead, we may cut them and have free
stuff, which is not at all what we set out to obtain. But if our tackle is dull—
i.e. the plate is well worn and, the bars are blunt—we can put our roll down
on the plate. Then, whether through fibrage on the bars, or the stuff being
drawn through by the vacuum of the beater-roll spaces, the process of 'fibril-
lation' commences. As every beater bar passes the plate, so many fibres will be
struck and bruised between the flattened surfaces of the bars and plate.
If a fibre is struck longitudinally, it may be divided into several fibrillae; if
across, it may still be fibrillated where the blow falls, thus exposing more surfaces
to the water in the beater. But it is bound to be the case that many fibres