The Daguerreian Society

On this day (January 22) in the year 1887, the following article filled 
the front page of the "Scientific American" (New York; [weekly] Vol. 
LVI., No.4.).  It is one of the best brief descriptions of the 
daguerreian process. Although Mr. Hopkins claims to have depended upon 
his "memory alone" for this description, certainly the wood-engraving 
line drawings accompanying the article were based on actual period 
daguerreian apparatus. 
  This article, along with its illustrations, is now available on
The Daguerreian Society's web site at:


DAGUERREOTYPY, although one of the most notable inventions of the 
present century, is already obsolete. It is nearly forgotten by those 
who practiced it, and is not preserved in all its details in the 
literature of photography. It is undoubtedly safe to say that a very 
small proportion of professional photographers, and a still smaller 
proportion of amateurs, have any practical knowledge of the subject. The 
writer, though never a professional daguerreotypist or photographer, 
very early in life acquired a practical knowledge of photography in the 
days when daguerreotypy was at its best. The interest then awakened has 
since been maintained through every phase of the growth and development 
of the art; and recently, depending on memory alone, the writer has 
extemporized apparatus, and successfully carried out the daguerreotype 
   It will be remembered that Niepce and Daguerre sought independently 
of each other for a method of producing sun pictures. Niepce at first 
employed plates coated with bitumen. He formed a partnership with 
Daguerre in 1829, but died before the invention now known as 
daguerreotypy was perfected.
   After the death of Niepce, Daguerre improved the art to such an 
extent that Niepce's son allowed it to go under its present name. Both 
inventors received annuities from the government for giving the 
invention to the public.
   In this country the art was first practiced by Morse, and was 
improved by Draper soon after it was introduced here.
   Daguerreotypy was very simple, easily understood, and easily managed, 
and was learned by many who found it a light business, requiring little 
capital and returning large profits.
   The plates employed were copper faced with silver. The metal was hard 
rolled, and the plates, as received from the manufacturers, were flat 
and quite smooth, but not polished. The first step toward the 
preparation of the plate for use was to clip the corners and turn down 
the edges slightly, in a machine designed for the purpose, to bring the 
sharp edges of the plate out of reach of the buff employed in producing 
the necessary polish.
   The plate was held, for scouring, in a block having clips on 
diagonally opposite corners for engaging the corners of the plate. One 
of the clips was made adjustable, to admit of readily changing the 
plates. The block was mounted pivotally on a support clamped to the 
table, as shown in Fig. 1.
   The scouring was effected by sprinkling on the plate the finest 
rottenstone from a bottle having a thin muslin cover over its mouth, and 
the rottenstone as well as the square of Canton flannel with which it 
was applied was moistened with dilute alcohol. The center of the Canton 
flannel square was then clasped between two of the fingers, and moved 
round and round with a gyratory motion until the plate acquired a fine 
dead-smooth surface. The last traces of rottenstone were removed by 
means of a clean square of flannel. The plate was then transferred to a 
block mounted on a swinging support, and buffed by the vigorous 
application of a straight or curved hand buff formed of a board about 
four inches wide and thirty inches long, padded with four or five 
thickness of Canton flannel, and covered with buckskin charged with the 
finest rouge. Scrupulous cleanliness was imperative in every step of the 
   The buffs were kept clean and dry, when not in use, by enclosing them 
in a sort of vertical tin oven, which was warmed by a small spirit lamp. 
A careful operator would prepare a plate having a bright black polish 
without a visible scratch, while an incompetent or careless man would 
fail in this part of the process, and would prepare plates full of 
transverse grooves and scratches. The beauty of the picture depended 
very much on the careful preparation of the plate.
   Occasionally, a buff would in some manner receive particles of matter 
which would cause it to scratch the plate. The remedy consisted in 
scraping the face of the buckskin, and brushing it thoroughly with a 
stiff bristle brush, generally a hair brush devoted especially to this 
use. The buff was then recharged by dusting on rouge from a muslin bag.
   When the rotary buff wheel was adopted, it insured rapid work, but it 
was otherwise no improvement over the hand buff. At first, the wheels 
were made cylindrical, but that incurred the necessity of an 
objectionable seam or joint where the leather lapped. The conical buff 
wheel (Fig.3) allowed the use of a whole skin, thereby dispensing with 
the seam.
   After buffing, the plate was taken to the dark room to be sensitized. 
The room had a side window, generally covered with yellow tissue paper, 
for the examination of the plate during the process. The room contained 
two coating boxes, one for iodine, the other for bromine. The 
construction of these boxes is clearly shown in Fig. 9, which is a 
longitudinal section of one of them. The two boxes were alike except in 
the matter of depth; the bromine box being about twice as deep as the 
iodine box.
   Each box contained a rectangular glass jar having ground edges. In 
the top of the box was fitted a slide more that twice as long as the 
box. In the under surface of one end of the slide was fitted a plate of 
glass, adapted to close the top of the jar, and in the opposite end of 
the slide was formed an aperture, furnished with a rebate for receiving 
the plate. Upon the top of the slide was arranged a spring-pressed 
board, which held the slide down upon the top of the jar.
   On the bottom of the jar of the iodine box were strewn the scales of 
iodine, and in the bromine box was placed quicklime charged with 
bromine. The bromine was added to the lime drop by drop, and the lime 
occasionally shaken until it assumed a bright pink hue bordering on 
orange. The lime was thus prepared in a glass stoppered jar, and 
transferred to the jar of the coating box as needed; one inch being 
about the depth required in the coating box. The polished plate was 
placed face downward first in the slide of the iodine box, and coated by 
pushing in the slide so as to bring the plate over the iodine in the 
jar. It was there exposed to the vapor of iodine until it acquired a 
rich straw color, the plate being removed and examined by the light of 
the paper window, and replaced if necessary to deepen the color. The 
plate was then in a similar manner subjected to the fumes of the bromine 
until it became of a dark orange color. It was then returned to the 
iodine box and further coated until it acquired a deep brownish orange 
color bordering on purple. The time required for coating the plate 
depended upon the temperature of the dark room. The process was very 
rapid in a warm room and quite slow in a cool room.
   The plate, rendered sensitive to the light by the thin layer of 
bromo-iodide of sliver, was placed in a plate holder, and exposed in a 
camera according to the well known method. The time of exposure was much 
longer than that of modern photography. A great deal depended on the 
quality of the lenses of the camera. The exposure in the best cameras 
was reasonably short. The old time gallery, with its antiquated camera 
and fixtures, and the dark room with the appurtenances, are faithfully 
represented in the engraving. After exposure, the plate was taken to 
another dark room for development. It was placed face downward over a 
flaring iron vessel, in the bottom of which there was a small quantity 
of pure mercury. The mercury was maintained at a temperature of 120 to 
130 degrees Fah. by means of a small spirit lamp. The temperature was 
measured by a thermometer attached to the side of the vessel. The plate 
was raised occasionally and examined by the light of a taper, until the 
picture was fully brought out, when it was removed from the mercury bath 
and fixed.*
   The fixing consisted merely in flowing over the plate repeatedly a 
solution of hyposulphite of soda, having sufficient strength to remove 
in about half a minute all the bromo-iodide of silver not acted upon by 
light. The plate was then thoroughly washed, and afterward gilded or 
toned by pouring upon it a weak solution of chloride of gold and heating 
it gently by means of a spirit lamp until a thin film of gold was 
deposited upon the plate and the picture attained the desired tone. The 
plate was then washed in clean water, and finally dried evenly and 
quickly over a spirit lamp.
   This operation added to the strength and beauty of the picture, and 
also served to protect the surface of the plate to a great extent 
against the action of gases.
   The finished picture was protected by a cover glass, and the edges of 
the glass and plate were securely scaled by a strip of paper attached by 
means of an adhesive coating.
  * A fortunate accident led to the discovery of the development of the 
photographic impression by means of the vapor of mercury. Previous to 
this discovery, the image was brought out by a long continued exposure 
in the camera. Daguerre on one occasion placed some under-exposed 
plates, which were considered useless, in a closet in which there were 
chemicals. Afterward, happening to look at the plates, he was astonished 
to find an image upon them. After taking one chemical after another from 
the closet until apparently all were removed, the images on his plates 
were still mysteriously developed. At length he discovered on the floor 
an overlooked dish of mercury, and the mystery was solved. He 
ascertained that the effects produced by the mercury vapor spontaneously 
given off could be secured at will by suitable apparatus.

(Transcriber's note: This anecdote of Daguerre's discovery of mercury 
development is generally considered spurious by  modern photo-
historians.  Original misspelling of the name "Niepce" was also 
corrected in this transcription. --Gary W. Ewer, 1995)
Posted for your enjoyment.      Gary W. Ewer       

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