The calotype is the paper-based photographic process developed by the Englishman William Henry Fox Talbot in 1840, then patented in 1841. It produces a negative on paper, from which you can then make, in theory, as many positives as you like by contact: this is the birth of the negative and positive pair.
This principle has never gone away. You can still get this paper negative today with a simple pinhole camera, a box pierced with a hole whose principle is explained in the pinhole photography guide. Understanding the calotype therefore means understanding where your own negative comes from.
The calotype in a few words
The word comes from the Greek kalos, beautiful, and refers both to the negative and to the positive print made from it. Talbot got there after several years of experiments. From 1834 to 1839, he observed how light darkens silver salts and made his “photogenic drawings”, simple imprints of objects laid on a treated sheet and then exposed to the sun, as the Bibliothèque nationale de France (in French) recounts.
The calotype appeared almost at the same time as the daguerreotype, made public in Paris in 1839. The two processes competed from the 1840s onwards, but they did not produce the same object at all.
William Henry Fox Talbot, two hawthorn leaves and a fig leaf, 1839, photogenic drawing (negative on paper). The J. Paul Getty Museum, Los Angeles, 86.XM.610. Public domain.
How Talbot made a negative on paper
The support is an ordinary sheet of paper. It is brushed with silver nitrate, dried, then dipped in a bath of potassium iodide: this forms silver iodide, which is sensitive to light.
Just before taking the picture, a solution of gallo-nitrate of silver is applied. The sheet, dry or still damp, goes into the camera obscura and receives the light for one to several minutes.
When it comes out, nothing is visible yet. The image is latent, and it is a fresh application of gallo-nitrate of silver that brings it out, as a negative. The sheet is then washed and fixed in hyposulphite of soda, the fixer proposed by John Herschel.
This point changes everything. For the first time, taking the picture and developing it became two separate steps, a feature kept by all the analogue photography that followed.
Calvert Richard Jones, [Young man], paper negative, late 1840s. The Metropolitan Museum of Art, New York. Public domain.
From negative to positive by contact
The positive is obtained through one last operation. The negative is laid on a sheet of salted paper, coated with sodium chloride and silver nitrate and then dried, and the two sheets are pressed tightly together in a printing frame.
The whole thing is exposed to the sun, negative on top. Where the negative is dark, little light passes through and the paper stays light. Where it is light, the light gets through and the paper darkens. The tones are reversed, and the print is fixed in turn.
In theory, then, a single negative can produce as many prints as you like. This is the decisive advantage over the daguerreotype, a direct positive on a silvered copper plate, and therefore one of a kind and impossible to reproduce.
The negative pressed against salted paper in the sun: the tones are reversed, and one negative gives several prints.
A soft look born of the paper fibre
The calotype also has an aesthetic of its own. The light passes through a paper negative, with its fibre and grain, and this texture carries over into the print.
The fibrous texture of the paper gives the image a softness, a velvety quality close to a pencil or wash drawing. Cast shadows are very black, outlines look as if they had been blended with a stump, and this character won artists over from the start.
A contact print made from a pinhole paper negative also keeps a little of this texture. The light passes through the fibre of the negative before reaching the fresh sheet, and the print bears the trace of it.
William Henry Fox Talbot, Winter Trees Reflected in a Pond, 1841-1842, salt print from a calotype negative. The Cleveland Museum of Art, 2006.4. Public domain.
A patent that held back its spread
Daguerre's invention entered the public domain. Talbot, on the other hand, protected the calotype with a patent in 1841, which limited its use in England for a long time.
He nevertheless promoted his invention. Between 1844 and 1846, he published The Pencil of Nature, the first printed book illustrated with original photographs pasted in. In Scotland, David Octavius Hill and Robert Adamson made many portraits with it in the 1840s.
It was in France that the process took off. Louis-Désiré Blanquart-Evrard improved it in 1847, then Gustave Le Gray invented the dry waxed-paper process in 1851, which was more sensitive and slightly translucent. These French stages of the paper negative extend the history of the pinhole camera and the camera obscura, which leads from the projected image to the image fixed on paper.
What the pinhole camera owes the calotype
A pinhole camera loaded with photographic paper repeats Talbot's gesture with modern chemistry. The paper at the back of the box receives the light, holds a latent image, then reveals it as a negative in the developer before being fixed.
To get a right-way-round image, you have two options: scanning, or a contact print on a second sheet. This second option is exactly that of the calotype, and it is explained step by step in the article on how to turn a paper negative into a positive.
The differences are real. Today's paper is manufactured already sensitised, it is handled under red light to which it is barely sensitive, and it develops in a few minutes. But the logic is the same: a negative on paper, then a positive by contact.
If you want to make your own paper negative and contact print it like Talbot, the Sténoflex mini-lab provides the pinhole camera box, ten sheets of photographic paper, the developer, the fixer and a red safelight filter. Your first negative will be, nearly two centuries on, a distant cousin of Talbot's.
As with Talbot: a negative on paper, then a positive contact printed on a second sheet.
Header image: William Henry Fox Talbot, The Open Door, salt print from a paper negative, before May 1844. The Metropolitan Museum of Art, New York. Public domain.
Éric Marais — Photographer, author of two books on pinhole photography (published by Pearson) and creator of the Sténoflex. Since the very beginning, he has run introductory workshops in pinhole photography and analogue developing.