Last Friday 5th April club member Harry Watson presented an entertaining review of historic photographic methods and experiments . This included a demonstration of salt prints an old process still practiced today.
Harry confided that while photography was invented, formalised is perhaps a better term, in 1839 in fact came about as the result of several hundred years of discovery, experiment and study in chemistry and optics.
Of the three main achievements leading to successful photography the camera is perhaps the oldest. There are ancient references to a small hole in the wall of a darkened room lead to an image of the outside scenery being projected in the opposite wall. The phenomenon was novel and became the basis for entertainment during the 17th century using tents in place of fixed buildings.
Subsequently artists were able to bring smaller structures on location in which they sat and traced the image of the surroundings on to tracing paper. The images themselves were made more visible using a lens to replace the simple ‘pinhole’ of earlier years.
Separately the tendency for certain chemicals to darken in the presence of daylight had been studied and attempts were made as early as 1802 to couple the effect to the camera. Although partially successful the images generated continued to darken when viewed, eventually becoming invisible. Importantly though it was found that the common denominator in these chemicals was Silver, compound with one or more of the so-called halogens. – Bromine, Chlorine, Iodine and less so Fluorine.
Returning to the 1830s several different groups continued to pursue the stability required to achieve permanent visibility. Of these groups two simultaneously and independently delivered workable methods. In France Louis Dagguerre used silver plate and iodine to create exquisitely detailed images with a mirror like background. These became hugely desirable and quickly swept the world, especially the USA. However while their beauty was undeniable their success was tempered because the image was a one-off and could not be faithfully reproduced. By around 1860 they had become largely surpassed by rival developments.
Meanwhile in Britain, Lacock Abbey in Wiltshire to be precise, an English scientist, inventor and photography pioneer named William Henry Fox Talbot had perfected an alternative. A weak solution of Sodium Chloride was brushed onto a sheet of paper, folded by one of Silver Nitrate to produce a coating of silver chloride, a strongly light sensitive medium. The salt Print had arrived and would become the basis of almost all photography up to the digital area and is still in use today. Talbot's method was crucially a double negative process. Because the light caused the silver to darken light areas of the scene appeared dark and vice versa delivering an inverted or ‘negative’ image. This was corrected by placing the negative on a second sheet of sensitive paper and exposing this to light. The result was that the negative was again inverted yielding a natural or positive image. Although the final image was not a detailed as the equivalent Daguerreotype it was significantly cheaper to produce multiple copies. The final result was stabilised by applying a solution of sodium thiosulfate [hypo] invented for his own reason by Sir John Herschel making the photograph light fast .
Salted Prints remained in use until around 1860 when the Wet Collodian method made it possible to create sharper and more stable negative on glass. At the same time Albumen Prints permitted sharper prints. Over time Dry Plates, Film, Gelatine and Resins all improved the quality and cost of photography, yet all of these developments share common ground with Fox Talbots proven use of Silver and the Double Negative - until of course the digital era dawned. Even now though the Salt print persists, be it for interest’s sake, to create quaint images with an authentic vintage look or to create realistic copies of delicate photographic artifacts.
The latter part of the evening was taken up when Harry demonstrated the Salt Print Process. Using a mixture of modern and vintage techniques for convenience Harry created a Salt Print image of the Club’s building.
This report is a synopsis of Harry's knowledgeable discussion and adroit talk. Those present thank him for such an entraining and informative event.
NEXT WEEK The best of PAGB Club Photography 2023
Harry Watson BNDCC
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