Two Ways to Make a Photograph With No Chemicals at All
Anthotypes bleach plant pigment out of paper; lumen prints print out on expired darkroom paper. Two camera-less processes that need no chemistry.
One uses crushed flowers. The other uses photo paper you were about to throw away.
What "no chemicals" actually costs you
Almost every camera-less printing process starts with a purchase. A cyanotype needs two iron salts. A salt print needs silver nitrate. Anthotypes and lumen prints need neither, and that is not a marketing claim about being natural or eco-friendly - it is a structural fact with consequences you will live with.
Both processes work the same way at the level of physics: something light-sensitive sits on a sheet, an object or a transparency lies on top of it, and the sun does the rest. What they are missing is the last step. In a finished photographic process, fixing is the stage whose entire job is to remove whatever is still light-sensitive, so the image stops reacting and stays put. Neither of these processes has one.
Everything strange about them follows from that single absence - the exposures measured in days, the colours that keep drifting after you bring the print indoors, the fact that serious practitioners scan their work and then put the original in a drawer. You are not making an object that lasts. You are making a photograph that is still happening.
The short version
- Neither process has a fixing step: that one absence explains the long exposures, the shifting colours and the fading.
- An anthotype is subtractive: plant pigment coated on paper is bleached away by sunlight, so the mask on top has to be a positive, not a negative.
- Exposure depends entirely on the pigment: turmeric and chlorophyll emulsions print in roughly two hours of strong sun, while petal and berry pigments run to days or weeks.
- A lumen print is ordinary darkroom paper left in daylight: the image prints out on its own with no developer, and fogged, decades-expired paper is the preferred stock.
- Impermanence is the medium, not a defect: an anthotype cannot be fixed at all, and fixing a lumen print bleaches its colours, so the working habit is to scan first and store originals in the dark.
Anthotype: sunlight used as an eraser
Why it needs a positive, not a negative
An anthotype starts fully coloured and gets destroyed into an image. You coat paper with juice pressed from petals, berries or leaves, dry it, lay something on top, and put it in the sun. Wherever light reaches the coating it bleaches the pigment out; wherever your object shades it, the colour survives. The image is what is left over.
That is the exact inverse of a cyanotype, which builds an insoluble blue pigment wherever light lands and therefore prints from a negative. Because an anthotype loses colour under light, the mask has to be a positive - a transparency of the picture the right way round, or the object itself. Practitioners print positives onto acetate on a domestic laser printer, and stack two identical sheets on top of each other when one is not dense enough to hold back the sun.
Making the emulsion
A mortar and pestle will get you there on one or two flowers; a blender needs a handful of petals but handles tough leaves and skins far better. One documented spinach recipe is two big handfuls pulverised with a cup of isopropyl alcohol, strained through a coffee filter and brushed onto cold-press watercolour paper. Alcohol rather than water is the common diluter, and straining matters - unstrained pulp leaves flecks of skin across the print.
Coat in a dim room and dry in the dark, because the emulsion starts bleaching the moment daylight reaches it. Use medium or heavy watercolour paper: this sheet is going to sit outdoors under glass for days, and thin paper will not survive the weather. Several coats, each dried before the next, give a deeper colour and a stronger final image than one thin pass.
How long it actually takes
There is no single answer, and anyone who gives you one is guessing. Turmeric emulsions are reported at around two hours in strong summer sun; a chlorophyll print from spinach can be done in about the same time, and some are overexposed by then. Petal and berry pigments are the slow ones, running to days or weeks. Herschel himself recorded that the juice of Japanese jute went quite white in roughly half an hour of sunshine, which tells you how wide the range is.
Exposure is cumulative, which makes the process fit around a normal life: printers put the frame out before work, bring it in at dusk, and repeat for days until the highlights have gone. The one thing that does not work is substituting convenience for sun. Ordinary indoor lighting will not expose an anthotype; beginners who get nothing after an hour under a household LED lamp get results immediately after switching to daylight or a proper UV source.
How the three camera-less processes compare
The trade is visible as soon as you put them next to each other.
| Process | What you have to buy | Typical exposure | What happens afterwards |
|---|---|---|---|
| Anthotype | Nothing - plants, a jar, watercolour paper | About 2 hours to several weeks, by pigment | Cannot be fixed; keeps bleaching in light |
| Lumen print | Nothing new - expired darkroom paper | 5 minutes to 2 months | Unfixed it keeps changing; fixing mutes the colour |
| Cyanotype | Two iron salts | About 2 to 30 minutes in sun | Plain water wash; stable, and light-faded prints recover in the dark |
Lumen prints: the paper that failed at its day job
Black-and-white darkroom paper has a shelf life. Left in a cupboard for decades it fogs, and a fogged sheet is useless for its intended purpose - it goes black the instant it touches developer, which is why boxes of it turn up cheap in house clearances and online auctions. That ruined paper is the ideal material for a lumen print. Printers who inherit a hoard of it describe the process as finally having a use for the stuff.
The method is almost embarrassingly short. Lay a flower, a leaf or a feather on the paper in daylight, weigh it down with a sheet of glass so it stays put and stays in contact, and leave it in the sun. No developer is involved: ultraviolet light converts the silver halides in the emulsion into visible metallic silver directly, an old behaviour called printing out. You watch the image appear over the course of the exposure rather than pulling it out of a tray.
Why the colours are unpredictable
Lumen prints come out in pinks, lilacs, browns, tans and blue-greys, and the specific colour is not something you choose. It depends on the emulsion in that particular sheet, and warm-tone fibre papers are widely reported as producing the most interesting range. Two prints made side by side on two different papers will not match. Moisture is the other variable: in summer heat the plant sweats against the paper where they touch, and that damp contact zone is a large part of where the colour shifts come from - which is also why a squashed, juicy plant can etch a halo into the sheet.
Exposure changes the result as much as the paper does. A five-minute exposure can give a light blue print with clean, sharp separation. Half an hour pushes it into warm purples with slightly less contrast. Two days takes it to a flat brown where the subject and the background start to merge. One documented two-month exposure went the other way and came back with more contrast than the two-day print, which nobody has a settled explanation for. There is no correct exposure time here, only the one you liked.
One practical note that surprises beginners: the print is a negative. The paper darkens where light hit it and stays pale under the object, so most people scan the sheet and invert it digitally to see the positive.
What gets repeated about these processes - and what printers actually find
Myth: an anthotype always takes weeks.
Reality: it depends entirely on the pigment you chose. Turmeric and spinach emulsions are reported printing in roughly two hours of strong summer sun. It is the petal and berry pigments that run to days or weeks, and a beginner who picks one of those and expects an afternoon result will conclude the process is broken.
Myth: you can expose either process indoors under a bright lamp.
Reality: ordinary room lighting will not do it. Beginners who spend an hour under a household LED and get a blank sheet get a working print as soon as they switch to direct sunlight or a dedicated UV source. Both processes are built around the sun, and that is not an aesthetic preference.
Myth: expired photographic paper is ruined and should be thrown away.
Reality: paper so fogged that it turns black the moment it hits developer is the preferred stock for lumen printing. Printers report lovely results from paper thirty years past its date, and treat a cheap box of it as a find rather than a write-off.
Myth: a lumen print has to be fixed or you will lose it.
Reality: fixer bleaches a lumen print and drains the colours that made it worth keeping. The common practice is to scan the print before fixing, because scanning does not affect it, and then either fix a duller permanent version or skip fixing entirely and store the original in the dark.
How to keep a print that cannot be fixed
- Scan or photograph it the day it comes out of the frame. For a lumen print this is the only way to keep the pre-fixing colours, and it costs nothing.
- Store originals flat and light-tight - a drawer, a box, anything that keeps daylight off them between viewings.
- If you hang an anthotype, keep it off any wall that gets direct sun. The shadow areas will bleach along with everything else and the image will flatten out.
- Treat an unfixed lumen as a live object. Framed and hung it will go on changing, and some printers hang them for exactly that reason.
- Fix a lumen print only after you have scanned it, and expect the colour to drop when it hits the tray.
- Write down the pigment, the dilution, the number of coats, the paper and the dates in and out. Nothing else lets you repeat a print you liked.
When you want one that stays
Spend a season on these two processes and the value of a fixing step stops being abstract. Both of them teach it by absence: you can have a photograph for free, and the price is that it never finishes.
The cheapest way to buy permanence back is the cyanotype, which came out of the same 1842 paper Herschel presented to the Royal Society as the anthotype did. It costs you two iron salts and gains you a development step - a rinse in plain water that carries away everything the light did not convert, leaving a pigment locked into the paper fibres with nothing light-sensitive left behind. It even behaves in the opposite direction under stress: a cyanotype that has faded in bright light will largely come back if you store it in the dark for a while, which an anthotype never does.
If that trade sounds worth making, the entry cost is genuinely small - a two-bottle sensitiser kit and a handful of things you probably own already covers it. What the plant and paper experiments give you first is the more useful thing: a feel for contact printing, for judging sun, and for the difference between an image that is finished and one that is merely paused.
Questions people ask before their first print
Do these processes really need no chemicals?
In their classic form, yes. A bleach-out anthotype is plant juice, paper and sunlight, with no development and no fixing. An unfixed lumen print is darkroom paper and sunlight, nothing else. The widely shared turmeric variant is the exception: it is developed in a weak borax or baking soda solution, which is a household chemical, so it sits slightly outside the pure version.
Can an anthotype be fixed so it stops fading?
No. There is nothing in the print to remove - the surviving image is unbleached pigment, and that pigment stays as light-sensitive as it was on day one. Its life is decided entirely by how much light reaches it, which is why practitioners treat the physical print as a record to be scanned and stored in the dark rather than as a permanent object.
Does expired darkroom paper still work for lumen prints?
It is the material of choice. Fogging that makes paper worthless for normal printing does not stop it printing out in daylight, and old emulsions are widely reported as giving the richer, stranger colours. Paper decades past its expiry date is actively sought out rather than avoided.
Which paper should I coat for an anthotype?
Medium or heavy weight watercolour paper is the safe starting point. The sheet will sit outside under glass for hours or days, so it needs to survive damp, heat and handling without buckling. Once you know how your emulsion behaves you can try other absorbent supports, but a fragile paper will fail before the exposure finishes.
Can I make an anthotype expose faster?
Pick a faster pigment first - turmeric and chlorophyll emulsions are reported at around two hours in strong sun, while petal and berry juices are the slow ones. Beyond that, several dried coats rather than one thin one, the strongest midday sun you can get, and a dense positive all help. Exposure accumulates, so putting the frame out on consecutive days works as well as one long stretch.