COUCH JACKETS 189
tacked on to the wooden ends, the latter must be perforated to allow the escape
of the water coming through the perforations of the shell, and holes corre-
spondingly punched in the covers. If roped on, the water will find its way
through the open folds between the stitches. It sometimes happens that a
cover works over one end of the roll. This may be owing to weight being
applied unequally on the levers, insufficient shrinkage, or to the cover not
having been pulled tight from side to side. If correcting the weights does not
send it back again, the best remedy is to loosen the tacks and refix, or put
in a fresh rope, tighten up and apply hot water to the rope. Rope for this
purpose can be obtained which tightens up and remains tight with the applica-
tion of moisture, and roping is the quickest and safest method of fixing. When
first put on, the coloured line of the cover will be approximately correct across
the roll, but later on will show a bend in the centre. This is to be expected
from the slight crown of the roll and the fact that the wire is tightest in the
centre. But if one side should take the lead a litde there is no cause for alarm.
It may be that the guard board is not so hard down, or so well fixed, or the
inclination of the couch rolls may not be exactly correct at both sides. The
roll may be more smooth at one side than the other, or the weights unequally
adjusted. If all arrangements are fairly accurate, the difference in the line will
be very slight, and will only go a short distance and may be discounted. But
if the line continues to go farther off the straight, the machineman may be
sure that some one or more of his adjustments are seriously wrong, or the
inclination of the two rolls requires skilled attention and correction from the
engineer.
In starting up with a new top jacket, unless the stuff is very 'free* and
can be well dried at the suction boxes, it will be found that the new nap picks
up fibres from the sheet. These accumulate until a small, flat patch of pulp
is formed, and a new jacket may be covered all over with these patches in a
few minutes.
The best remedy is to have the guard board well adjusted and hard down
at the start. (It should be eased off again as soon as die jacket has become
'seasoned*.) The suction should be used to the utmost and as little weight
as possible put on the roll. If the cover is run for a few minutes before starting
up, with a hot mixture of resin size and china clay in the water channel of the
guard board, there will be less trouble of this sort. Where it is possible, warm
water, in pkce of cold, should be used in the water channel to dean off the
patches of fibres.
In any case, it is best to start up with a new jacket at a speed slow e&oogfc
to have a good control of the stuff at the suction boxes, and the wire as tight
as safety permits.