262

MODERN PAPER-MAKING

In some mills it has been possible to dispense with alum altogether, since it is
now recognised that size is not required in newsprint. In general, however,
troubles such as sticky presses are likely to arise if the stock is not kept down to
a pH value of about 5.

Alum solution is a very corrosive liquid and must be handled in lead-lined
or other suitably protected tanks and pipe lines.

The dyes used for newsprint are almost exclusively basic dyes because they are
cheap, they are bright colours, they dye directly without difficulty and the fact

[Wdlwkys (Bury\Ud.
Re. ii i.—BREAKER AND BEATER FLOOR FOR THE PREPARATION OF STOCK FOR Two MODERN NEWSPRINT
MACHINES
that they are fugitive is of no consequence. In modern mills they are dissolved
in bulk, and added to the stock at die proportioned This is a clean and con-
venk&t method of dyeing, as the beater floor is kept completely free from dyes,
and dhades caa be more quickly and easily controlled the nearer they are added
ftp tbc naftrtitni* itself.
, x of Stock— The preparation treatment of baled pulp
fcr B^kkg aewsgcgit stock consists essentially in breaking up the laps aad then
sfategWteg dbe fibres so dbat they are finally all separated! from one another
,»iBiifocm suspeasioa reaidy to flow on to die wke of the paper machine.