IMPROVEMENTS IN THE PROCESS AND MEANS OF OBTAINING THE REPRESENTATION OF OBJECTS OF NATURE AND AET
Year: 1843

page_text: CLAUDET'S SPECIFICATION.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ANTOINE
FRANCOIS JEAN CLAUDET, of High Holborn, in the County of Middlesex,
Glass Merchant, send greeting.
WHEREAS Her nost Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of Great Britain, bearing
date at Westminster, the Twenty-first day of November, in the seventh
year of Her reign, did, for Herself, Her heirs and successors, give and
grant unto me, the said Antoine François Jean Claudet, Her especial
licence, full power, sole privilege and authority, that I, the said Antoine
François Jean Claudet, my exors admors, and assigns, and such others
as I, the said Antoine François Jean Claudet, my executors, adminis..
trators, or assigns, should at any time agree with, and no others, from
time to time during the term of years therein mentioned, should and
lawfully might make, use, exercise, and vend, within England, Wales,.
the Town of Berwick-upon-Tweed, and in all Her Majesty's Colonies and
Plantations abroad, and in the Islands of Jersey, Guernsey, Alderney,
Sark, and Man, an Invention of "IMPROVEMENTS IN THE PROCESS AND
MEANS OF OBTAINING THE REPRESENTATION OF OBJECTS OF NATURE AND AET,
being a communication from a foreigner residing abroad; in which which
said Letters Patent is contained a proviso, obliging me, the said Antoine
François Jean Claudet, by an instrument in writing, under my hand and
seal, particularly to describe and ascertain the nature of my said Inven-
tion, and in what manner the same is to be performed, and to cause the
same to be enrolled in Her Majesty's High Court of Chancery within six
calendar months next and immediately after the date of the said in part
recited Letters Patent, as in and by the same, reference being thereunto
had, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Antoine François Jean Claudet, do hereby declare that the nature of the
said Invention, and the manner in which the same is to be performed,

page_text: is particularly described and ascertained in and by the following
description thereof (that is to say);-
The process which I have to specify consists in rendering the
daguerreotype picture susceptible of producing by printing a great
number of proofs or copies, thereby transforming it into a complete
engraved plate. The process is established upon the following facts,
which have been discovered by the Inventor:-
First. A mixed acid, composed of water, nitric acid, nitrate of
potassa, and common salt, in certain proportions, being poured upon a
daguerreotype picture, attacks the pure silver, forming a chloride of that
metal, and does not affect the white parts, which are produced by the
mercury, but this action does not continue long. Then by a treatment
with ammonia (ammonia containing already chloride of silver in solution
is preferable for this operation), the chloride of silver is dissolved and
washed off, and the metal being again in its naked state, or cleansed
from the chloride, it can be attacked afresh by the same acid. This acid
acts better warm than cold.
Second. As all metallic surfaces are soon covered (when exposed to the
atmosphere) with greasy or resinous matters, it is necessary, in order that
the action of the acid upon the pure silver should have its full effect,
that the surface should be perfectly purified. This is effected by the
employment of alcohol and caustic potash.
Third. When a daguerreotype picture is submitted to the effect of a
boiling concentrated solution of caustic potash before being attacked by
the acid, the state of its surface is so modified that the acid spares or
leaves in the parts which it attacks a great number of points, which form
the grain of the engraving.
Fourth. When the effect of the acid is not sufficient, or, in other
words, if it has not bitten deep enough, the effect is encreased by the
following process:-Ink the plate, as copper-plate printers do, but with
a siccative ink. When the ink is sufficiently dry, polish the white parts
of the plate, and gild it by the electrotype process; then wash it with
warm caustic potash, and bite in with an acid which will not attack the
gold, but only the metal in those parts which, having been protected by
the ink, have not received the coating of gold. By these means the
engraving is completed, as by the action of the acid alone it is not
generally bitten in deep enough.
Fifth. To protect the plate from the effects of wear produced by the
operation of printing, the following process is employed:-The surface of

page_text: he plate is covered with a very thin coating of copper, by means of the
lectrotype process, before submitting it to the operation of printing, and
when that pellicle or coating of copper begins to shew signs of wear, it
nust be removed altogether by plunging the plate in ammonia, or in a
veak acid, which, by electro-chymical action, will dissolve the copper
vithout affecting the metal under it.. The plate is then coppered again
y the same means, and is then ready for producing a further number
f impressions. This re-coating operation may be repeated as many
imes as may be required.
The following the following is the description of the whole process,
which is divided into two parts, consisting of a preparatory and finishing
rocess:-
First Preparatory Engraving-For this operation, which is the most
elicate, it is necessary to have,-
1st, a saturated solution of caustic potash.
2d, pure nitric acid at 36 degrees of the areometer of Baume (specific
gravity 1'333).
3rd, a solution of nitrite of potassa, composed of-
100 parts of water
5 parts of nitrite
☐ in weight.
in weight.
4th, a solution of common salt, composed of-
Water, 100 parts
Salt, 10 parts
5th, a weak solution of ammoniacal chloride of silver, with an excess
of ammonia. The ammoniacal chloride of silver must be diluted
with 15 or 20 parts of pure water. In the description of the process,
this solution will be called ammoniacal chloride of silver.
Sixth, a weak solution of ammonia, containing four or five thousandths
of liquid ammonia. This solution will be called ammoniacal water.
Seventh, a weak solution of caustic potash, containing four or five
thousandths of the saturated solution, which will be called alkaline
water.
Eighth, a solution composed of―
Water
-
Saturated solution of potash
Alcohol-
-
4 parts
2 parts in volume.
- 1 part
This solution will be called alcoholized potash.
Ninth, acidulated water composed of

page_text: Besides, it is necessary to have three capsule or dishes, made of porcelain,
large enough to contain the plate, and covered with an air-tight piece
of ground plate glass, and two or three more capsulæ, which do not
require to be covered; two or three glass funnels to wash the plate, and
two or three glass holders in the shape of a spoon or shovel, by which
the plate is supported when put in and taken out of the solution, without
touching it with the fingers. The daguerreotype plate is submitted to
the engraving process after having been washed in the hypo-sulphite of
soda, and afterwards in distilled water.
First Process for Biting-in or Engraving the Plate.-The following
solutions must be put in the capsulæ in sufficient quantity, so as to
entirely cover the plate;-1st, acidulated water; 2nd, alkaline water;
3rd, alcoholized potash; 4th, caustic potash; these two latter in covered
capsule; 5th, distilled water. The plate being put upon the glass holder
or spoon is plunged in the acidulated water, and agitated during a few
seconds, then put into a glass funnel, and washed there by pouring upon
it some distilled water. It is taken again with the glass spoon and
plunged in the capsule containing alcoholized pot ash. This capsula s
covered with its glass cover, and then heated, by means of a spirit lamp,
to about one hundred and forty-four degrees Fahrenheit. The plate
must remain in the capsula half an hour, during which the solution is
heated now and then, and agitated during that time. The following
acid solution, which will be called normal acid, must be prepared. It
is composed as follows:-

page_text: and as much acid as the plate can hold is poured upon it from the bottle;
then it is heated with the spirit lamp, but without attaining the boiling
point. During this operation it is better to stir or move about the acid
on the plate by pumping it, and ejecting it again by means of a pipette
or glass syringe. After two or three minutes the acid is thrown away,
the plate is put in the glass funnel, and there well washed with water,
and afterwards with distilled water B. Then, without letting the plate
dry, it is put upon the fingers of the left hand, and with the
right hand some ammoniacal chloride of silver, which is moved
about the surface by balancing the hand, is poured upon it.
The solution is renewed until the chloride formed by the
action of the acid is dissolved; then the plate is washed by
pouring upon it a large quantity of ammoniacal water, and afterwards
some distilled water C. Without allowing the plate to dry it is then
put in the caustic potash, and the capsula being placed upon the stand,
it is heated up to the boiling point; then it is left to cool D; and beginning
again the operations described from A to D, a second biting is obtained;
and by repeating again the operations described in A and B, a third
biting is produced. The plate is then dried; in this state the black parts
of the plate are filled with chloride of silver. The plate is then polished
until the white parts are perfectly pure and bright. This polishing is
done with cotton and "ponce" (pumice stone); afterwards, the chloride
of silver filling the black parts is cleansed by the means described in B
and C. The plate is dried, but before drying it, it is well to rub the
plate slightly with the finger, in order to take off from the black parts
any remains of an insoluble body, which generally remains on it. The
preparatory engraving is then finished, and the plate has the appearance
of a very delicate aquatint engraved plate not very deeply bitten in
Nevertheless, if the operation has been well managed, and has been
successful, it is deep enough to allow the printing of a considerable
number of copies.
Note. Sometimes, instead of treating the plate with the boiling
potash in the capsula, a similar result may be obtained by placing the
plate upon the stand, covering it with the solution, and heating it by
means of a spirit lamp, until, by evaporation, the potash becomes in a
state of ignited fusion. By this means the grain is finer, but the white
parts are more liable to be attacked.
Last Operation of Biting-in.-This operation requires some of the
re-agents before named, and also, first, a siccative ink made of linseed
oil, rendered very siccative by boiling it sufficiently with litharge, it may

page_text: be thickened with calcined lamp black. Second, an electro-type appa-
ratus and some solutions fit to gild and copper the plate.
Means of Operating.-The plate must be inked as copper-plate printers
do, taking care to wipe off the white parts more perfectly than they
generally do, and put the plate in a room sufficiently warm until the ink
is well dried, which requires more or less time, according to the nature
of the oil employed. The drying of the oil may be hastened by heating
the plate upon the stand with the lamp, but the slow process is more
perfect and more certain. When the ink is well dried, the white parts
are cleansed again by polishing the plate with cotton and "ponce," or
any other polishing powder. A ball of cotton, or any other matter,
covered with a thin piece of caoutchouc or skin can be used for this
purpose. When polished, the plate is ready to receive the electro-
chemical coating of gold, which will protect the white parts.
Gilding The gilding is obtained by any of the various processes of
electrotyping which are known. The only indispensable condition is
that the surface obtained by the precipitation must not be liable to be
attacked by any weak acid; a solution answering this purpose is make
of ten parts, by weight, of ferrocyanide of potassium, one part of chloride
of gold, and one thousand parts of water, used with a galvanic battery.
During the gilding the plate must be turned in several positions, in
order to regulate the metallic deposit. In some cases the gilding may
be made more perfect if the plate is covered with a thin coating of
mercury before being put in the gilding solution. When the plate is
gilded, it must be treated with the boiling caustic potash by the process
already indicated for the preparatory engraving, in order to cleanse it
from all the dried oil or ink which fills the hollows. The plate is then
washed and dried, and when the oil employed has been thickened with
the lamp black, the surface of the plate is rubbed with a crumb of bread,
in order to cleanse and take off the black remaining, then the white
parts, being covered and protected by a varnish not liable to be attacked,
and the black parts being uncovered and clean, the plate can be bitten
in by aquafortis, according to the ordinary process used by engravers.
This operation must be done upon the stand, and not by immersing the
plate in the solution. Before this last biting-in, if the preparatory
engraving has not succeeded well, and the plate still wants a sufficient
grain, it can be given by the various processes of aquatint engraving.
Before submitting the plate to the operation of printing, in order to
insure an unlimited number of copies, it is necessary to protect it by a
slight coating of copper, which is obtained by the electrotype process,

page_text: otherwise the printing would soon wear the plate. This coating must
be kept very thin in order not to destroy the fineness of the engraving
and the polish of the white parts. In that state the plate can be
delivered to the printer. After a certain number of impressions have
been obtained, it will be perceived that the coating of copper is worn
in some places; then this coating must be removed and a fresh one
applied in its place. For this purpose the plate must be purified and
cleansed by warm potash, and plunged in a weak acid composed as
otherwise the printing would soon wear the plate. This coating must
be kept very thin in order not to destroy the fineness of the engraving
and the polish of the white parts. In that state the plate can be
delivered to the printer. After a certain number of impressions have
been obtained, it will be perceived that the coating of copper is worn
in some places; then this coating must be removed and a fresh one
applied in its place. For this purpose the plate must be purified and
cleansed by warm potash, and plunged in a weak acid composed as
follows
Water
Nitric acid
Nitrous acid of engravers
600 parts
50 parts
in volume.
5 parts
This acid will dissolve the coating of copper, and the plate being coppered
again by the same means as before, may be submitted anew to the opera-
tion of printing; and as nothing can prevent the repetition of the same
operation over and over again, any number of impressions can be
obtained. The coating of copper can also be removed by caustic
aminonia. The daguerreotype plate engraved by this process may be
also reproduced and multiplied by the electrotype process as any other
engraved plate. The essential points of this process, which constitute
the Invention which has been communicated to me, and for the exclusive
use or employment of which I have obtained the herein-before in part
recited Letters Patent consist,-
First, in the discovery and employment of certain properties of a
mixture composed of nitric acid, nitrous acid, and hydrochloric acid in
determined or fixed proportions. The two last acids may be employed
either in a free state or combined with alkaline or other bases. This
mixed acid has the property of biting the pure silver which forms the
black parts of the daguerreotype picture without attacking the white
parts formed by the amalgam of mercury. The result of the action of
the biting is to form on the black parts of the picture an insoluble
chloride of silver, and this chloride of silver, which, when formed, stops
the action of the acid, is dissolved by ammonia, which allows the biting
to continue.
Second, in the discovery of certain properties of a warm solution of
caustic potash, and in the employment of the said solution by which the
mercury forming the picture is better and deeper amalgamated with the
silver under it, so that many imperceptible prints of the amalgam are
effected in such a manner that the acid has no action upon them.
Third, in the discovery and employment of a process which produces

page_text: a grain favorable to the engraving, by which the biting on the plate is
rendered deeper; this is effected by filling the parts engraved with a
siccative ink, or any other substance, and then gilding the plate by the
electrotype process. The gold is not deposited on the parts protected
by the ink. When the plate is gilded, the ink is cleansed by the caustic
potash, and the plate may be submitted to the effect of an acid which
does not attack the coating of gold, but bites only on the silver in the
parts already engraved by the first operation.
Fourth, in the employment of a process by which the plate is pro-
tected from the wear of the printing operation; this is effected by cover-
ing the plate before printing with a slight coating of copper by the
electrotype process, and when the coating begins to wear by printing
it is removed by a weak acid, or by ammonia, which dissolves the copper
without affecting the silver under it. The plate is coppered again, and
after another printing the same operation is repeated, so that a con-
siderable number of copies may be printed without much injuring the
engraving.
In witness whereof, I, the said Antoine François Jean Claudet, have
hereunto set my hand and seal, this Twenty-first day of May, in
the year of our Lord One thousand eight hundred and forty-four.
Inrolled the same Twenty-first day of May, in the year above written.