H2 MODERN PAPER-MAKING
Engine or resin-sized broke, usually a lower grade of stock (wood or wood
and esparto or straw), has rather a different effect. It produces a paper that
feels more pliable and refined than can readily be obtained without it, even
after longer beating of fresh fibres. This is especially noticeable with broke
that has been through the edge runner, but pulper broke has this effect also,
though in a lesser degree. This is no doubt owing to the action of these machines
having more of a softening and fibrillating effect on the fibres than the
beater.
A very great deal depends on how the broke was beaten in the first place.
Broke from fine, free-beaten stuff will usually reduce the strength of any paper
into which it is introduced, since the operations of pulping, clearing, etc., must
of necessity reduce the length of the fibres still further. This must be borne
in mind when using broke in the furnish for thin substances, particularly those
with a water-mark, when the too lavish use of poor broke will cause a deal
of trouble with pick-ups at the dandy roll. With heavier substances, water-
marking will be assisted, the letters on the dandy roll sinking well into the
layer of soft, fine fibres on the surface of the web.
Again, broke, even fine, short-fibred stuff, will increase the strength of
paper as in the following instance:
It sometimes happens that a chest of stuff is found to be too raw— i.e. in-
sufficiently fibrillatedL The resulting paper will have a dull water-mark, a
harsh feel, and be lacking in strength. An esparto paper beaten thus will give
trouble by sticking to the press rofls.
By adding about 10 to 15 per cent of well-cleared broke, the rawness of
the stuff will be overcome and the water-mark improved. The strength, will
be increased because the broke fills up the interstices of the sheet and forms a
binding for the long raw fibres. The surface is made more level and uniform
and the press rolls do not so readily pluck up individual fibres. As broke
usually causes increased shrinkage on the drying cylinders, it may be used to
assist in getting the correct register of water-marks. Increased retention of
loadings, heavy colours, closer finish, etc., are also gained. Most paper-
makers will agree that they would always add broke to the furnish if it were
available.
Broke and Waste.—In a mill where there are a great many changes of deckles,
etc., owing to the making of small lots, and many different grades and colours,
there is, unavoidably, a great deal of broke and more or less waste of fibres.
It is essential that this broke and waste be minimised as much as possible, and
this depends on the efficiency of the machinery and the skill of the workers
in handling it; also on the care taken in the handling of rags, half stuff, reels,
sheets, etc. Trucks of rags and half stuff should never be overloaded or piled