REFINING 95

notably those that are soft and well boiled. The fibres that are most success-
fully treated by refiners are, however, those that we have already mentioned
as requiring 'free beating'—i.e. mechanical pulp, esparto, etc. The fibres
from broke and waste paper, which have been already treated for paper-making,
and require only to be defibred, form another class which can be 'beaten' by
the refiner, provided always that they are well saturated with water in the
beater or breaker.

The use of the refiner has been extended in many mills using the above
classes of stock, to cover nearly the whole of the beating, the beaters or breakers

[Btnttey andJackson
FIG. 32.—THE MARSHALL REFINEK, Disc END
This refiner has a disc as well as a cone, and the disc is chiefly used for dealing the stuff and freeing it from knots
themselves being used for little more than the preliminary mixing of the stuff,
alum, size, dye, etc.
The wisdom of this method is open to question, because the refiner is
worked hard up, and fibres that ought to be brushed out and fibrillated (the
proportion of chemical wood in newsprint, for example) are cut fine to give a
close sheet, and so their full value is not obtained.
The refiner being a modified type of beating engine, it is, of course, possible
to beat certain papers by means of a series of refiners, the stock being passed
from one engine to another. A strong 'bond* paper may be produced from
chemical wood pulp in this way, especially successful being those mills wliicfi
can get their pulp straight from the digester. It is difficult to see what is gamed