The ABC of photography ‘types’

Fox Talbot: Dawn of the Photograph opened at Media Space, part of the Science Museum, in London last week. Using a mixture of images, artefacts, letters, and publications, the exhibition charts the development of photography by William Henry Fox Talbot against the backdrop of his contemporaries. For anyone with a smidgen of interest in the history or science of photography, it’s a must-see exhibition.

As I wandered about the exhibition, getting high on its heady mix of photography and history, it occurred to me that a crib sheet of the early photographic processes, detailing their steps and requirements as well as their progress and their pitfalls, would be a useful article. So here you have it: from daguerreotype to tintype, an ABC of early photography.

Daguerreotype

• Louis Jacques Mandé Daguerre
• Development period: 1824 to 1839

Daguerre might be recognised as the man who developed the first practical photographic process, but his experiments were far from the first forays into attempting to draw with light.

Before Daguerre came Niécephore Niépce, with his heliographic experiments throughout the 1820s, and Thomas Wedgwood was producing sun-prints as early 1802.

However, these processes weren’t practical. Niépce’s heliographs required hours of exposure–hardly convenient for a family portrait or sports reporting–and Wedgwood’s sun-prints, which were effectively silhouettes burned onto paper that had been sensitised to light with silver nitrate, faded rapidly.

Niépce was interested in the reproducibility of his images, but Daguerre recognised that time was of the essence. By taking a silver plate and bringing it into contact with iodine, he was able to photo-sensitise it. After exposing it to light, the image could be revealed on the plate using mercury vapour. The plate itself was the image; there was no print-making process for it.

(You’ll notice the prevalence of lethal chemicals throughout the history of photography. It’s a wonder anyone survived long enough to make a breakthrough.)

These first images faded fast, much like Wedgwood’s sun-prints, because the previously unexposed silver nitrate would then be exposed when the image was displayed. Steadily, the exposed and unexposed areas would all become exposed and the image would recede into nothingness. The solution was simple, and salty. By washing the plate in a solution of table salt, it dissolved the unexposed silver iodide and fixed the image.

One image, painted with light. But literally one image. Daguerreotypes were not reproducible.

Calotype

• William Henry Fox Talbot
• Patented 1841
• Means ‘beautiful picture’
• Also known as the talbotype

Reproducibility is where the calotype surpassed the daguerreotype.

A calotype is created by coating paper in silver nitrate solution, drying the paper, and then immersing it in potassium iodide, which creates a layer of light-sensitive silver iodide. Next the paper needs to be washed in gallic acid, dipped in water, and blotted dry before before inserted into the camera for exposure. As soon as it has been exposed, it’s washed again in gallic acid and fixed with hypo before being washed and dried. What you have then is a negative image. With a calotype, it can be enjoyed as-is, but it can also be reproduced as salt paper prints.

Talbot might have cracked the negative image, patented the calotype process, and been able to charge astronomical sums for its licences, but it wasn’t without its problems. Poor chemistry, poor air quality, and water pollution all meant that the images could fade, and reproductions from paper negatives can lack detail. And when someone is charging a fee for a licence, there will be someone else looking to undercut him.

Ambrotype

• Variant of the wet collodion process
• Wet collodion process developed in 1851 by Frederick Scott Archer
• Ambrotype possibly developed by James Ambrose Cutting

The ambrotype is just a version of the wet collodion process, and to be honest, that’s what we’re really interested it.

The wet collodion process was developed in 1851 by Frederick Scott Archer. Exposures didn’t take an age and it was patent-free. For anyone who couldn’t afford Talbot’s licence fee for the calotype or had been disappointed by its failures, the wet collodion process was an attractive alternative.

Take one glass plate. This will serve as your negative. Coat it evenly with a mixture of soluble iodide and collodion. In a darkroom, immerse the plate in a solution of silver nitrate to form a light-sensitive silver iodide coating. While the plate is still wet, insert it into the camera and expose it. Develop the negative with a solution of pyrogallic acid and fix it with either sodium thiosulphate or potassium cyanide. Once it has been washed and dried, it can be used to create albumen prints.

Sure the wet collodion process came with its fair share of trickiness–it was messy and time-sensitive–and potassium cyanide is hardly the stuff of teddybear’s picnics, but exposures could be obtained in a matter of minutes. This is progress.

As for the ambrotype, it was an under-exposed wet collodion negative mounted on black paper or velvet.

Tintype

• A variant of the the ambrotype, which was itself a variation on the wet collodion process

Finally comes the tintype. It’s a variation on the ambrotype. Where the ambrotype was created from a glass plate, the tintype was produced using a much cheaper metal plate, enamelled black and coated with collodion emulsion. Much of the photography of the US Civil War was produced using tintypes, and street and beach photography in the later nineteenth century was usually tintype, too.

So, now that you have your early photography-types crib sheet, you can go and enjoy the Fox Talbot exhibition with a sounder understanding of what the pioneers of photography were using and the obstacles that they faced.