Clive Heritage-Tilley describes some unusual photographic applications using chemistry pioneered by Sir John Herschel
Photography is a classification given to images produced by the action of light. This involves using a material sensitive to light, or one that undergoes some chemical or physical change when exposed to light. Nature provides us with many such substances. Some will fade or darken, some are changed due to molecular decomposition and others because their molecules condense and polymerise (join together to form larger molecules). Light can also make some materials less soluble in certain solvents, others more soluble. All of these effects can be adapted as a photographic process.
Pioneers working in the dawn of photography were searching for the most efficient and practical route to produce quality images. It is not surprising therefore; that they should concentrate on materials with high sensitivity to light and the reaction of halogen based substances in combination with metallic salts. In particular - those of the metal silver. As Digital photography moves us into new areas of image making, we should not forget that old science still has many creative possibilities, a fact self evident by the number of people practising historical photographic processes. No doubt as digital photography becomes the prime method of recording images, then chemical photography can take its rightful place as a fine art process.
When looking at some of the earliest pictures, many of us are struck with the presence and preciousness of the images; it is almost as though you can feel the power and concentration of their original creators. For those interested in trying to emulate some of these historic styles, may I draw attention to an extremely basic process which is perhaps worthy of more investigation, namely actino-chemistry. This is the name Sir John Herschel gave to the effect of light on various substances, and experiments in this field were also carried out by others during the late 18th and early 19th century.
In 1842, Sir John Herschel produced a paper entitled - “On the action of the rays of the solar spectrum on vegetable colours, and on some new photographic processes.” His experiments used solutions derived from such simple sources as plants and flowers.
Herschel’s investigations into actino-chemistry were mainly carried out using prismatic separation, which involved coating paper with various solutions and exposing them to individual colours of the spectrum, with the aid of a flint glass prism. It must be remembered that these experiments were conducted during the early evolvement and excitement of new photographic processes. His benchmarks were calotypes and daguerreotypes. Had he had enough time and the right equipment he may eventually have produced some form of early multi coloured images using a similar principle to colour separation. It was probably the colour aspect which induced him to choose substances most impractical in terms of light sensitivity.
The use of flower juice as a medium, later referred to as anthotype (from the Greek for flower) has some interesting possibilities. Although impractical for the evolution of photography, the process provides simple image integrity, some of which can be quite beautiful. This, as are many of the other non silver processes, are worthy of further study within the context of fine art.
Using a non-camera application some interesting effects can still be obtained using plant or flower juice. The action of direct sunlight will have a bleaching effect; either totally, or in some cases leaving a residual tint, on which the action of light is very much slower. People who work with natural dye materials may recognise that some of these effects are the non-fast light properties associated with many organic substances.
In order to start exploring the possibilities of this process, I conducted a series of tests followed by attempts at producing complete images. I was fortunate to be able to conduct my experiments from a well stocked garden, although some of the plants which I would like to have experimented with, were not always available.
Method - Extraction of juice from flowers may be carried out by pulping the petals either with a little de-ionised water or alcohol. This can be done with a small pestle and mortar, or similar device. The resulting liquid is a coloured tincture, which may then be used for coating the paper. My initial experiments on various flowers were made with ethyl alcohol, but found the colouring matter was getting somewhat destroyed, and so switched to using other solvents and basic lighter fuel, the latter of which seemed in many cases to work quite well. However, deionised water is simpler and provides purer colour from the flower. To ensure the tinctures did not suffer too much light exposure prior to use, after pulping and filtering, I bottled them in miniature dark jars (see slide 1) and stored them away from light. My tests were conducted on many varieties of flowers, with some at different times in the flowering cycle. Indeed as Herschel had pointed out, the colours vary according not only to the time in the season, but perhaps also with the time of day at which they are gathered. He observed that the earlier flowers are more sensitive than those produced even from the same plant, at a later period in its flowering, and have their colours more completely discharged by light.
Where possible I tried to experiment with those flowers pointed out by Herschel to provide the most positive reaction. The colours extracted from particular flowers are not always as expected. Indeed in many cases the colours have no resemblance to the original flower and very poor reaction to light, on this basis a large variety can be discounted. Two that do work quite well are the petals of the common poppy and peony flowers.
As a base material, I used white cartridge paper, which first had to be sized (stretched by soaking it in water and sealing it onto a board with gum strip). A similar preparation to that used on paper prior to water-colour painting. When dry it can be coated with the flower tincture using a small paint brush (see slide 2) and left to dry, preferably in subdued lighting conditions. Exposure within a camera is not really feasible with the sort of exposure times required, and the images are therefore obtained by contacting the subject directly onto the paper, just as photograms or contact prints are produced.
Using a couple of wooden frames, with plate glass sheets and cushioned with thin layers of foam rubber to protect the glass, the images were produced in the same way that old contact printing frames were used, but with greatly extended exposure times. For these experiments, the subjects were 5” X 4” negatives and film positives (see slide 3), together with some small flower specimens. It is essential to ensure that the specimen or negative is in tight contact with the coated paper, and small clamps placed each side of the frame will allow this (see slide 4). A thin sheet of foam rubber placed on the back of the paper support will allow the clamps to be tightened, without the risk of cracking the glass. The duel colouring that appears on some of the images is due to part of the subject flower colouring, staining into paper and mixing with the tincture under the pressure of the glass. An effect that can be quite pleasing, although there is no reason why the process may not lend itself to the use of multiple tinctures on the same sheet of paper.
Exposure - For reasonable anthotypes to be produced (depending on the tincture involved), the frame needs to face directly into the sun. Some strong direct sunshine, in the order of 2 to 3 days is required, or even more if the sun is intermittent with slight cloud cover. An overcast sky is not recommended for this process, as it needs some good strong sunshine. Most substances left in the sun for long enough will undergo a change of colour and humidity and decomposition also comes into play, in some cases, when using flower specimens, producing small discharges of gas. This can be troublesome, as initially I had several pieces of glass cracking due to gas expansion within the frame. The problem was solved by drilling a series of holes through the back of the base boards, but off image area to allow any gasses to escape.
Development - This is not necessary, as after exposure the contact material is removed and the paper simply cut from the frame.
Fixing the image - By virtue of the very way in which anthotype images are produced, direct strong sunshine for hours or days at a time, it would suggest that the images could be viewed under normal indoor lighting conditions and not fade appreciably for some time. I still have a test image on the wall of my dinning room dated 18/7/96, which shows no discernible signs of fading, and indeed some of Herschel’s originals still survive today.
In conclusion I would like to mention that by virtue of the almost limitless species which have never been experimented with, the process has great potential in terms of colours and effects. I would be interested to learn from others who may be practising in this area of photography, especially those who also have botanical interests or live in sunnier parts of the world.
To wet peoples appetites for experimentation I quote from a statement in Herschel’s paper- “Corchorus Japonica - The flowers of this common and hardy but lightly ornamental plant, are a fine yellow, somewhat inclining to orange, and this is also the colour the expressed juice imparts to paper. As the flower begins to fade the petals whiten, an indication of their photographic sensibility, which is amply verified on exposure of the stained paper to sunshine. I have hitherto met with no vegetable colour so sensitive. If flowers be gathered in the height of their season, paper so coloured (which is of a very even and beautiful yellow) begins to discolour in 10 or 12 minutes in clear sunshine, and in half an hour is completely whitened. The colour seems to resist the first impression of light, as if by some remains of vitality, which being overcome, the tint gives way at once, and the discoloration when commenced goes on rapidly. It does not even cease in the dark when once begun. Hence it happens that photographic impressions taken on such paper, which when fresh are very sharp and beautiful, fade by keeping, visibly from day to day, however carefully preserved from light.”
Note - Corchorus Japonica is known today as Kerria japonica or Jew’s mallow in the Rosaceae.
All images © Clive Heritage-Tilley