ADDING BROKE TO FURNISH in
effects may be obtained by apparently the same causes. The only way of giving
any sensible explanation is to give instances.
In the case of a machine making waterleaf paper, high-class writings or
drawings for hand-sizing, or blottings, with no resin size, alum or loading, it
would seem that no doubt would arise as to the effect of adding, say, 10 per
cent of the same paper in the waterleaf condition.
It is the fact, however, that the stock may be made either more 'free* or
more Vet5. If the broke is taken straight^ from the machine to the beater
and added to stuff nearly ready to be put down to the stuff chest, the result
will be a freer paper. Under these conditions blotting paper will acquire a
hard and harsh 'feel5.
This is owing to the fibres having lost their saturated condition coming
over the drying cylinders, and to the time in the beater required for pulping
being insufficient for them to become again saturated to the same extent. Also,
no doubt, some of the finer fibrillae will have been lost through the wire and
suction boxes.
Now, if the broke is filled in with the furnish at the commencement of the
beating, the fibres will become thoroughly saturated with water and become
more highly fibrillated than when first run over the machine, producing a
wetter stock. Thus the same quality of broke added at different periods of
beating will give two different results. Waterleaf broke that has been stored
long enough to have regained its normal hygroscopic condition will invariably,
on being repulped, reach the machine in a wetter condition than when it was
first made. In this instance the fibres have had time to soften and lose the
tension or stress set up by the heat of the drying cylinders, and in a lesser degree
by the pressure of the couch and press rolls, and are immediately susceptible
to additional fibrillation.
If the broke is packed into the beater in sufficient quantity to increase
materially the consistency of the stuff, higher fibrillation is certain.
Broke from tub-sized papers always produces wetter stuff. In most cases
it is added in a given quantity with the furnish in the beater, and if it has not
been boiled or overheated, the size (gelatine and resin) will still be effective
and give hardness and cohesion to the sheet.
Also it shortens the beating time considerably, since its treatment in. the
pulper or edge runner has produced more fibrillation, and the beater takes up
"the work at a point a good deal further advanced than when the stock was
fint made into paper. The other items of the furnish will not require so much
beating as they otherwise would, die fibrilke necessary being supplied firoDa
the broke. For this reason all broke from strong papers should be kept for
use in the same quality.