Thanks to a happy union of vitamin C and rosemary, making a developer natural can be kept for up to 70 days !!!.
Over the course of my research, rosemary gradually established itself as one of the best natural ingredients for making an alternative developer.
Today, among all my experiments, it is the product I favour without hesitation: it is effective, stable, can be kept, and of an extraordinary chemical richness. Why rosemary?
Rosemary does in fact contain a set of particularly powerful active molecules:
- Monoterpenes (essential oils).
- Phenolic diterpenes: carnosic acid, carnosol, rosmanol.
- Terpenes: ursolic acid, oleanolic acid.
- Phenolic acids: rosmarinic acid, caffeic acid.
- Flavones: luteolin.
These components are known for their antioxidant, antimicrobial and antifungal properties.
The results obtained in my tests with an evolving storage time.
After making one litre of rosemary developer, I wanted to carry out successive tests, depending on how well this same developer kept.
- I developed 4 black-and-white films (6×6 and 24×36 formats), developing each time—and, for economy in 35mm format, only a strip of 18 frames from each film.
- At the beginning of my tests, after 18 days of storage of this developer, then after 23 days, 51 days, 63 days, and finally, to conclude these tests—because you do have to stop at some point—I developed, after 70 days of storage, a 36‑exposure film rated at ISO 400. I kept this developer in an opaque bottle, protected from light, in a dry place at room temperature!
- I should add that after each development, I decided to increase the development time by 2 minutes to compensate for the progressive storage times and the depletion of the reagents, keeping each time the same starting temperature—namely 25°—and agitating my tank with simultaneous inversions and rotations for 10 seconds every minute.
- I also developed, always in the same developer, 14 fibre‑based (baryta) prints in 18×24 format, after 26 days of storage.
The results were surprising and remarkable—stable, contrasty and homogeneous.
When developing paper sheets whose emulsion had been coated on a baryta base, I ultimately obtained a yellowish coloration in my prints.
Making natural rosemary developer.
You can use fresh leaves or dried leaves.
Both work, but I still recommend favouring dried leaves, which will release their active molecules better during the decoction. If possible, at a minimum, let your herbs dry in a dry place protected from light, for at least about two weeks.
Decoction.
- Place 30 g of dried rosemary leaves in 1.2 litres of natural cold water. Let them soak for 5 minutes.
- Then bring the contents to a boil and maintain a simmering decoction for 15 minutes.
- Let it cool to lukewarm, then filter—ideally using a very fine nylon coffee filter.
For a decoction intended to make a film developer, I proceed in the same way but with a few adjustments. In fact, this time it is important to use demineralized water for your herbal decoction in general, in order to avoid later traces of limescale or other stains that could appear on or in the emulsions during the processing of your films or rolls.
One of the keys to this success is the pairing of these two developing agents, vitamin C with rosemary!
Vitamin C (ascorbic acid) is made up of small molecules that act very quickly and deeply within the silver emulsion and are highly reactive. Here they have the particularity of working on the recording of the shadows and ultimately produce little contrast. Rosemary, on the other hand, made up of larger molecules, works more on the surface of the emulsion in the highlights; however, it will need more time to obtain detail in these highlights.
In short, the size of the molecules of these two developing agents therefore comes into play in their final combined action, namely: the speed and penetration of the natural rosemary developer into an emulsion.
Finally, after my tests, I found that after each development—and without changing the developer’s temperature—it was necessary to increase the development time by two minutes.
Révélateur au romarin pour films noir et blanc.
In the product of your decoction, preferably stabilized at 22°, dissolve, in the following order:
1 12 g of vitamin C (instead of 15 to 20 g for papers).
2 47 g of sodium carbonate.
3 6 g of iodized salt.
4 Add 2 drops of dishwashing liquid at the end of preparation to improve the penetration of the developer into the emulsion.
Always filter your natural developer before use.
Film development parameters:
- Temperature: 25°.
- Duration: 17 to 20 minutes. (depending on how long your developer has been stored
- Agitation: 5 to 10 seconds every minute, by inverting and rotating the tank.
Rosemary developer for grading baryta paper prints.
1 15 to 20 g of vitamin C.
2 47 g of sodium carbonate.
3 6 g of iodized salt.
Finally, add 2 drops of dishwashing liquid to improve the penetration of the developer into the emulsion. Check the pH value as you go, as each product is dissolved.
Afterwards :
- Adjust, as far as possible, the pH to around 10.5, and if it is a little too high, lower it with a bit of citric acid (2 to 3 g at a time—no more—and check).
- Filter again before use.
Paper development temperature: 33 to 36°.
Duration: 3 to 6 minutes, depending on the desired rendering.
Important reminder.
Store your rosemary developer carefully in a sealed opaque container protected from air, and if possible filled right to the top. Close it tightly in order to minimize, during storage: oxidation.
Botanical information.
Rosemary (Salvia rosmarinus), an aromatic plant in the Lamiaceae family, shares its family with mint, thyme, lavender, sage, wild thyme, lemon balm, basil, oregano, savory or even marjoram.
It stays green all year long, naturally resists pests and is easy to grow, whether in the garden or in a pot. It can be harvested all year round, particularly on limestone soils.
Jacques Revon
Honorary journalist, author, photographer.
https://fr.wikipedia.org/wiki/Jacques_Revon
