An anthotype is an image created using photosensitive material from plants. This process was originally invented by Sir John Herschel in 1842. An emulsion is made from crushed flower petals or any other light-sensitive plant, fruit or vegetable. A coated sheet of paper is then dried. Place some material, for example leaves or a transparent photo positive on the paper and expose to direct full sunlight until the image part not covered by the material is bleached out by the sun rays. The color remains in the shadowed parts. The paper remains sensitive against such rays.

The photo-sensitive properties of plants and vegetables have been known to scholars for centuries. Among many early observations the experiments of Henri August Vogel in Paris are of particular interest. He discovered in 1816:

An alcoholic tincture of either red carnations, violets or corn poppy turned white behind blue glass in a few days, while it remained unchanged behind red glass after about the same time. Cotton and paper colored with these tinctures exhibited the same differences.

Later that century Herschel attempted to invent a color process, he tried several flower and plant emulsions and published his findings. His research resulted in the anthotype process. It should be pointed out that his research into making photographic images from flowers was limited and was ultimately abandoned since no commercial application was feasible from a process which takes days to produce an image. The process continued to be listed in photographic literature of the time but was likely little used.

Over time the process has earned a misleading reputation for being simply too impractical. Image permanence have been brought into question to this day but this problem seems to be mostly related to choice of flower or plant matter.

How it works
This process was probably discovered in 1816 by Henri August Vogel in Paris. Even Sir John Herschel looked in the 19th century with the anthotype and published his results.

From an examination of the researches of Sir John Herschel on the coloring matter of plants, it will be seen that the action of the sun’s rays is to destroy the color, effecting a sort of chromatic analysis, in which two distinct elements of color are separated, by destroying the one and leaving the other. The action is confined within the visible spectrum, and thus a broad distinction is exhibited between the action of the sun’s rays on vegetable juices and on argentine compounds, the latter being most sensibly affected by the invisible rays beyond the violet. It may also be observed, that the rays effective in destroying a given tint, are in a great many cases, those whose union produces a color complementary to the tint destroyed, or, at least, one belonging to that class of colors to which such complementary tint may be preferred. For instance, yellows tending towards orange are destroyed with more energy by the blue rays; blues by the red, orange and yellow rays; purples and pinks by yellow and green rays.
— Henry H. Snelling

Alcoholic extracts from suitable plant varieties that contain anthocyanins such as corn poppy, chrysanthemums, dahlias, marigolds and the like. a. are applied to thicker, not too strongly absorbent paper. Dye extracts with water and fruit extracts are also possible. After drying, exposure is then carried out under a negative or object for a long time (sometimes for weeks). The most effective ingredient is ultraviolet light. The plant dyes exposed to the light fade, while the light-protected areas retain their color. (Some plant dyes also go dark when exposed to light.)

The duration required depends above all on the specific dye and the sun’s radiation, but also on moisture, which in some cases greatly reduces the necessary exposure time. In the presence of moisture, plant material used as a template can also decompose itself.

The created pictures (or photograms ) can – as no fixation is possible – only be kept protected from light. Then they are very long-lasting.

Film positives on transparent film can be used as templates, since light areas become light due to fading and dark areas remain dark due to the shading. You can also use objects such as leaves, stones, combs and many others as templates. The result is a photogram.

Other flower suggestions
Henry H. Snelling writes based on his research: “Viola odorata–or sweet scented violet, yields to alcohol a rich blue color, which it imparts in high perfection to paper. Senecio Splendens — or double purple groundsel, yields a beautiful color to paper.”

Bingham, quoting by Sir John Herschel, recommends Corchorus japonicus flower (japanese Jute) for a “fine yellow colour” that “upon exposure to sunlight, it is in about half an hour rendered quite white”.

The procedure is based on the ability to react to the light of some plant juices (or their alcoholic extracts), changing color. Among the most reactive plant varieties there are those containing anthocyanins, such as:

calendula (very sensitive to light – should react after 15 minutes)
red cabbage
yellow chrysanthemum
dark red dahlia (good photosensitivity)
red rose

The red wine can be directly applied and exposed (exposure time: less than 12 hours)

Plants or flowers are ground with a mortar, or a blender, to extract the dyes they can be used:

distilled water
pure alcohol

After several days in a warm dark place it can be filtered.

The absorbent paper is coated with a brush or by dipping it in the solution, then it is illuminated by placing it under an object or frame, keeping in mind that the covered parts will remain the original color, while the exposed ones will fade.