Daguerreotype: Here's Looking at Me

Louis-Jacques-Mandé Daguerre circulated a notice in 1838 to attract investors in his recent invention of the daguerreotype. He described his eponymous invention as follows: "The daguerreotype is not merely an instrument which serves to draw nature . . . [it] gives her the power to reproduce herself."¹ A year later Francois Arago, the head of the Academie des Sciences in Paris, publicly disclosed Daguerre's photographic process.

First, a silver-plated sheet of copper was polished to the point of reflecting like a mirror. Next, the plate was exposed to vapors of iodine in order to make the plate light sensitive by creating a surface of silver iodide. The plate was then ready to be placed into the daguerreian "camera" (a modification of the camera obscura, in which the prepared daguerreotype plate took the place of the original tracing glass). At this point the lens cap was removed and the prepared plate was exposed to the incoming light. Exposure times varied, usually fifteen to twenty minutes in the beginning, with ever shorter intervals as chemistry improved and advancements in the technology of the lenses and cameras became available. Once exposed, the plate still appeared devoid of a representation; however, it now possessed a latent image of what was before the camera. Still in the dark, the exposed plate was then held over fumes of heated mercury at a forty-five degree angle. Almost like magic, the image would appear, as the mercury molecules adhered to the lighter parts of the image. The final step of bathing the image plate in a salt solution fixed the image forever by sensitizing the darker parts of the image. As a result of this process the mercury coated areas appeared white and the silver areas, once bathed in the salt solution, appeared black. The image was usually protected by a plate of glass, held in place by a gold-plated mat, and contained as a precious memento in a small, embossed leather case or a carefully crafted plastic "Union" case, adorned with velvet on the inside and tiny brass clasps on the outside.

The wizardry of its image is encapsulated by the view initially that the daguerreotype was a product of alchemy: magical because of its combination of mysteriously superimposing the subject's image on the polished silver plate and of doubling as a mirror to include the reflected face of the viewer.

1. Louis Daguerre as quoted in Susan Sontag's Anthology of Quotations in her book On Photography (New York: Farrar, Straus and Giroux, 1978), 188.

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