1.2. The process of daguerreotyping
1. cleaning and polishing the [silvered side of a copper-]plateIt is apparent from this list that daguerreotyping involved the handling of a lot of chemicals and materials. Even if one had the money to procure all the necessary equipment, one also needed the skill and dexterity to perform each single step with the right timing. The process was also dangerous because the iodine silver- and quicksilver-vapors involved in the process were toxic. This is a far cry from the slogan "You press the button, we do the rest", with which Kodak advertised at the turn of the century and which neatly summarizes our modern understanding of (amateur) photography.
Besides the complexity of the technical procedure, two other features distinguished the daguerreotype: the simultaneity of positive and negative image; and the long exposure time. Both features had separate effects on the picture and on the beholder which play a certain role in The House of the Seven Gables. When Holgrave initially introduces himself to Phoebe, his profession does not meet much enthusiasm with her. She answers his invitation to look at some of his works with the following words: "A daguerreotype likeness, do you mean? [...] I don't much like pictures of that sort - they are so hard and stern, besides dodging away from the eye, and trying to escape altogether. They are conscious of looking very unamiable, I suppose, and therefore hate to be seen." (p. 91) What Phoebe describes here is not her own personal and idiosyncratic experience of daguerreotypes, but a feature inherent to the new medium itself. All daguerreotypes had this "Manichean aspect" , that they simultaneously contained a positive and a negative image. Which one the beholder saw depended upon the way in which he tilted the plate.
This unnerving and disquieting quality of the daguerreotype had a simple technical reason. After the developing-process was finished, the coating of the plate consisted of two different chemical compounds: the light portions of the picture consisted of the quicksilver amalgam, the dark ones of iodine silver. Thus, if one looked at the picture without any light shining on it, one beheld a positive image. But because the amalgam was unreflective and the iodine silver reflective, this changed if the daguerreotype was held under light. The formerly dark portions reflected the light and became brighter as the unreflective parts: one beheld a negative image. If the onlooker's face was visible in the reflecting parts, there appeared a third ghostly image somewhere between the positive and the negative image of the daguerreotyped person.
Another technical singularity of the daguerreotype with somewhat disquieting effects was the long exposure time. In the early days it took 35-40 minutes to get a visible image, but more sensitive coatings and the use of advanced chemicals rapidly reduced the time of exposure. In the early fifties an ordinary daguerreotype made in a portrait-studio still took about 30 seconds. Thus, "human countenances, if reproduced at all, were seen on the plate with outlines blurred or features distorted from the ordeal of holding still while the long exposure was made."  Great demands were made on the facial muscles of those who wanted their picture taken. Often intended expressions (smiles, frowns) vanished from the face, which then looked "hard and stern", as Phoebe complains.
Though hardness and sternness may have often been the intended expressions, they were also the effect of a certain lack of any expression. Emerson, who initially thought the daguerreotype to be a spiritually truthful medium, was disappointed by his own portraits: "[U]nhappily, the total expression escaped from the face and [you found] the portrait of a mask instead of a man."  This mask-like quality of many daguerreotyped faces was reinforced by contraptions which photographers invented to prevent movement: head braces and neck vices rather dispelled any natural expression on the customer's face.
It was especially hard to take daguerreotypes of kids, who tended to keep moving in front of the camera. Their movements on the laps of their mothers led to ghostly images: while the rigid mother was clearly visible, her child only appeared as a blur, as a barely visible phantom fidgeting beneath her. The only way to get a distinct picture of a child was to photograph it after its death. At the middle of the last century, when child mortality was still very high, this was a common enough practice. The advertisements of daguerreotypist's portrait studios were often pitched at the newly bereaved and most of the studios were equipped with various mourning accessories. Holgrave's postmortem portrait of the Judge (cf. pp. 302) thus would not have bewildered his contemporaries as much as it does the modern reader.
If the long time of exposure often led to blurred or "hard and stern" countenances, it had even more singular effects on daguerreotypes of street scenes: all cities were transformed into ghost towns in which no moving objects and beings were to be seen. In 1839 Samuel F. B. Morse describes one of these daguerreotypes in an article:
Objects moving are not impressed. The Boulevard [...] was perfectly solitary, except an individual who was having his boots brushed. His feet were compelled, of course, to be stationary for some time, one being on the box of the boot black, and the other on the ground. Consequently his boots and legs were well defined, but he is without body or head, because these were in motion. 
||The Paris Boulevard as described by Samuel Morse. There seems to be only one inhabitant left in the French capital with nothing better on his mind than clean shoes. Ghostly images like this one reinforced the daguerreotype's reputation as being a device closely connected to paranormal phenomena.|