IMPROVEMENTS IN THE MANUFACTURE OF PAPER AND IN APPARATUS EMPLOYED THEREIN
Year: 1884

page_text: I WARREN WILLIAM DE LA RUE of 110 Bunhill Row in the City of London
Manufacturing Stationer do hereby declare the nature of my Invention for
"IMPROVEMENTS IN THE MANUFACTURE OF PAPER AND IN APPARATUS EMPLOYED
THEREIN" and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement:-
This Invention has for its object improvements in the manufacture of paper and
in apparatus employed therein.
The usual way in which a water-mark is produced upon paper made in the paper
machine is by means of a roller called the "dandy roll" which is caused to roll
along the sheet of paper pulp whilst the fibres of which the same is composed are
still capable of movement amongst themselves. The surface of the dandy roll is
commonly of wire gauzo and pieces of wire are sown upon the gauze to form
projections. In the use of the dandy roll these projections coming into contact
with the sheet of pulp displace the fibres and hence. the finished paper appears
thinner in the parts with which the projections upon the dandy roll have been in
contact.
I have for some years past (under a Patent granted to William Frederick
De La Rue N° 1462 in the year 1869) used dandy rolls having a surface of
embossed wire gauze.. The indentations in the gauze are inwards and they cause a
thickening of the paper where they are brought into contact with it. Theso
thickenings correspond in form to the configuration of the design of the water mark.
I have also affixed wire to the surface of such dandy rolls so as to form
projections in order to thin the paper where the projections come into contact with
it. By this means I have obtained light lines in the watermark strengthening the
effect of the thickened and opaque design.
According to my present Invention I form the surface of the dandy roll of wire
gauze embossed in such manner that parts of the surface of the gauze corresponding
to the configuration of the design of the water mark are raised and project out
from the general surface and other parts corresponding to the line shading of the
design are depressed below the level of the general surface.
The annexed Drawing shows diagrammatically and greatly enlarged a section of
a portion of the surface of a dandy roll made in accordance with my present
Invention.

page_text: a represents the section of a ridge or projection raised on the surface of the gauze ;
it and similar ridges or projections serve by the means already explained to
produce the configuration of the watermark as it is exhibited by the paper.
represents the section of a groove or depression in the wire gauze which with
other similar grooves serves to produce an opaque shading to the design, is an
auxiliary ridge or projection serving to define the shading line and to intensify it
by driving the pulp into the groove or depression b. Further effects may be
obtained by attaching wires to the dandy roll either in the usual way where the
surface is unembossed or upon the raised parts a which give the configuration to
the water mark.
In place of forming the ridges or projections a which produce the configuration
of the water mark by raising portions of the wire gauze above the general surface
they may be formed by sewing on suitably shaped slips of wire gauze or of sheet
metal perforated all over with fine holes on to the surface of the gauze which is
embossed with the grooves or depressions 6 but it is much to be preferred that both
the ridges or projections a and the grooves or dépressions b should be produced by
embossing the gauze.
Having now particularly described and ascertained the nature of my said
Invention and in what manner the same is to be performed I declare that what
I claim is
First. A dandy roll with a surface of wire gauze embossed so that parts standing
above the general surface of the roll produce the configuration of the water mark
and other parts depressed below the general surface of the roll produce opaque
shading to the design.
Second. A dandy roll with a surface of wire gauze embossed with ridges or
projections a of the general configuration of the water mark, grooves or depressions b
corresponding to opaque shading of the design and other auxiliary ridges.or
projections c defining and intensifying the shading lines.
Third. A dandy roll with a surface of wire gauzo embossed so that parts stand
above and other parts below the general surface of the roll and with wire sewn on
either to the general surface or to the raised parts.
Fourth. A dandy roll with a surface of wire gauzo embossed so that parts are
depressed below the general surface and with pieces of wire gauze or of perforated
sheet motal corresponding to the configuration of the water mark attached to tho
surface of the embossed gauze and forming projections above the general surface of
the roll. .
Fifth. The manufacture of paper with a water mark of which the general
configuration is indicated by a thinning of the paper and the shading by a
thickening thereof by means of dandy rolls substantially as herein described.