AN IMPROVED METHOD OP OBTAINING A WATER-MARK ON PAPER, AND IN APPARATUS EMPLOYED THEREIN
Year: 1869

page_text: LETTERS PATENT to William Frederick De la Rue, of Bunhill Row,
in the City of London, for the Invention of "AN IMPROVED METHOD
OP OBTAINING A WATER-MARK ON PAPER, AND IN APPARATUS EMPLOYED
THEREIN."
Sealed the 29th June 1869, and dated the 12th May 1869.
PROVISIONAL SPECIFICATION left by the said William Frederick De
la Rue at the Office of the Commissioners of Patents, with his
Petition, on the 12th May 1869.
I, WILLIAM FREDERICK DE LA RUE, of Bunhill Row, in the City of
London, do hereby declare the nature of the said Invention for "AN
IMPROVED METHOD OF OBTAINING A WATER-MARK ON PAPER, AND IN APPARATUS
EMPLOYED THEREIN," to be as follows:-
This Invention has for its object an improved method of obtaining a
water-mark on paper, and in apparatus employed therein.
In order to obtain a water-mark on paper in the process of manu-
facture in the paper machine it is customary to use an openwork roller,

page_text: called a dandy roll, on which pieces of wire or metal are sewn to form
the pattern desired. The paper pulp, whilst still semi-fluid as it is
carried forward by the machine, passes under this roller, and the raised
pieces of metal upon the roller where they come in contact with the
pulp displace it and produce a thin place at each point of contact. As
soon as the pulp leaves the dandy roll the water is drawn out of it by
suction, and the pattern is thus set.
Now according to my Invention I make a dandy roll with a sunk in
place of a raised pattern upon it, and I find that the soft pulp enters the
depressions of this roller so as to make a thicker paper at the parts
corresponding with these depressions, whilst the paper is left elsewhere
of a uniform and even thickness. In this way a paper with a thickened
water-mark may be made by machinery, whereas heretofore such papers
have always been made by hand in a different manner. I make the
surface of the dandy roll of fine wire gauze with the pattern accurately
sunk into the surface. This gauze I support on a stouter gauze also with
the pattern sunk into it, so that it may the better sustain the finer gauze
forming the surface of the roller. The roller itself is made of wirework,
as is usual with dandy rolls, and the gauzes to form the pattern surface
are sewn around it. If desired a more elaborate water-mark may be
obtained by fixing on the surface of a dandy roll made according to my
Invention pieces of wire or metal, which, on coming in contact with the
pulp thin it in the same way as the common dandy roll acts. Parts of the
water-mark will in this case be thicker, and other parts will be thinner
than the rest of the paper.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said William Frederick De la Rue in the Great Seal
Patent Office on the 12th November 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
FREDERICK DE LA RUE, of Bunhill Row, in the City of London, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twelfth day of May, in the year of our
Lord One thousand eight hundred and sixty-nine, in the thirty-second
year of Her reign, did, for Herself, Her heirs and successors, give and

page_text: grant unto me, the said William Frederick De la Rue, Her special
licence, that I, the said William Frederick De la Rue, my executors,
administrators, and assigns, or such others as I, the said William
Frederick De la Rue, my executors, administrators, and assigns, should
at any time agree with and no others, from time to time and at all
times thereafter during the term therein expressed, should and lawfully
might make, use, exercise, and vend, within the United Kingdom of
Great Britain and Ireland, the Channel Islands, and Isle of Man, an
Invention for "AN IMPROVED METHOD OF OBTAINING A WATER-MARK ON PAPER,
AND IN APPARATUS EMPLOYED THEREIN," upon the condition (amongst others)
that I, the said William Frederick De la Rue, my executors or admi-
nistrators, by an instrument in writing under my, or their, or one of
their hands and seals, should particularly describe and ascertain the
nature of the said Invention, and in what manner the same was to be
performed, and cause the same to be filed in the Great Seal Patent Office
within six calendar months next and immediately after the date of the
said Letters Patent.
NOW KNOW YE, that I, the said William Frederick De la Rue, do
hereby declare the nature of the said Invention, and in what manner the
same is to be performed, to be particularly described and ascertained in
and by the following statement thereof, that is to say :-
This Invention has for its object an improved method of obtaining a.
water-mark on paper, and in apparatus employed therein.
In order to obtain a water-mark on paper in the process of manu-
facture in the paper machine it is customary to use an openwork roller,
called a dandy roll, on which pieces of wire or metal are sewn to form
the pattern desired. The paper pulp, whilst still semi-fluid, as it is
carried forward by the machine passes under this roller, and the raised
pieces of metal upon the roller where they come in contact with the
pulp displace it and produce a thin place at each point of contact. As
soon as the pulp leaves the dandy roll the water is drawn out of it by
suction, and the pattern is thus set.
Now according to my Invention I make a dandy roll with a sunk in
place of a raised pattern upon it, and I find that the soft pulp enters the
depressions of this roller, so as to make a thicker paper at the parts
corresponding with these depressions, whilst the paper is left elsewhere
of a uniform and even thickness. In this way a paper with a thickened

page_text: water-mark may be made by machinery, whereas heretofore such papers
have always been made by hand in a different manner. •
In carrying my Invention into practical effect I make the surface of
the dandy roll of fine wire gauze with the pattern accurately sunk into
the surface. This I do by pressing the gauze between two metal plates
or forms accurately fitted together, the pattern being in relief on the one
plate and sunk into the surface of the other, but when the plates are
placed one on the other the depressions in the one plate are not com-
pletely filled by the pattern in relief on the other, a space being left
between the two corresponding to the thickness of the wire gauze. The
wire gauze which I employ is of copper with, say, 60 holes to the linear
inch, the gauze is placed between the plates or forms, which are then
by hydraulic or other suitable, pressure made to approach each other
whilst kept truly parallel, and with the patterns accurately corresponding.
When the gauze has been thus pressed to the extent which it is judged
that it will bear without injury it is removed and annealed, and it is
then again similarly pressed and annealed until the pattern in the gauze
is brought to the full depth. The number of annealings necessary
depends on the nature and depth of the pattern. The depth of the
pattern will vary according to the strength of the water-mark required,
one thirty-second of an inch is sufficient to produce a well-defined and
bold mark. The gauze thus prepared for the surface of the dandy roll
I support on a stouter gauze, also with the pattern sunk into it, so that
it may the better sustain the finer gauze forming the surface of the
roller. This stouter wire gauze, which may have about 22 holes to the
linear inch, is embossed with the pattern in a similar manner to that
already described, but not necessarily with the same care, and the
hollows are formed larger by so much as is necessary to allow the
pattern on the finer gauze to fit down into them. Under these gauzes
again I prefer for some patterns to use another coarser gauze unem-
bossed, but cut away at the parts where the pattern comes, it serves to
support the upper gauzes at the parts where there are surfaces of some
extent without pattern. The roller itself is made of wirework, as is usual
with dandy rolls, and the gauzes to form the pattern surface are sewn
around it in the same way that the gauze is ordinarily fixed on dandy
rolls. Where the quantity of paper required is small a less efficient
means of supporting the surface gauze may suffice, the second embossed
gauze being dispensed with. Where the pattern consists of straight

page_text: parallel lines I sometimes use but one embossed gauze, and I support the
parts between the lines to prevent them from being crushed down by
wires sewn upon a plain wire gauze underneath the embossed gauze.
This method of supporting the embossed gauze may be applied in other
patterns. If desired a more elaborate water-mark may be obtained by
fixing on the surface of a dandy roll made according to my Invention
pieces of wire or metal, which on coming in contact with the pulp, thin
it in the same way as the common dandy roll acts.. Parts of the water-
mark will in this case be thicker, and other parts will be thinner than
the rest of the paper. These pieces of wire or metal are sewn on in the
same way as in making ordinary dandy rolls.
In working with my improved dandy rolls care is taken so to place
them as to operate on the pulp when it is of a proper consistency, just
as when working with an ordinary dandy roll.
In witness whereof, I, the said William Frederick De la Rue,
I have hereunto set my hand and seal, this Eleventh day of
November, in the year of our Lord One thousand eight hundred
and sixty-nine.
WILLIAM F. DE LA RUE. (L.S.)