Once the exposure is over, the photo already exists on the paper, but you cannot see it yet. The light has left an invisible imprint on it, called the latent image, and it is the developing chemistry that will make it appear before your eyes. This page details the three developing baths, their order and their role, then the step from paper negative to positive.
Developing means passing the paper through three baths in turn, the developer, the stop bath and the fixer, then rinsing it. Each bath has a precise role, and the process is the same as in a traditional darkroom, as the practical guide to pinhole photography points out.
Working under red safelight
Everything happens under a red lamp, called a safelight, because black and white photo paper is not very sensitive to red. You can see what you are doing, you can follow the image as it comes up, and the sheet does not fog as long as the lamp stays at a good distance. This is the whole advantage of paper over film, which has to be developed in total darkness.
This dark room lit in red is the darkroom, and a bathroom with its daylight leaks blocked is quite enough to get started.
Equipment for the three trays
Line up three trays, one per bath, in the order the paper will go through them. A pair of tongs lets you handle the sheet without dipping your fingers into the chemicals or mixing the baths from one tray to the next.
The Sténoflex kit supplies the developer and fixer as concentrated liquids in two bottles of 15 ml each, to be diluted according to the instructions before the session.
The developer brings out the image
Slide the sheet into the first bath, sensitive side up, and rock it gently so that the liquid covers it in one go. The image then appears, first the blacks, then the greys, within a few tens of seconds.
This is the most striking moment of the process, and in workshops it is always the one that makes people smile. Leave it for the indicated time, around one to two minutes depending on the product and the temperature.
The indicated time remains a guide, and an image that has reached its deep blacks is ready even before the time is up: watching matters as much as the clock.
The stop bath halts development
Without this step, the developer would keep working and the image would darken until it fogged. The second bath neutralises the developer at once and freezes the image at the moment that suits you.
A few seconds to half a minute is enough, with gentle agitation. A simple bath of clean water, or even slightly vinegary water, does this job for a first developing session, and above all it avoids contaminating the fixer with developer carried over by the sheet.
The fixer makes the image stable in light
At this stage, the image is visible but still fragile, because the paper still holds sensitive salts that would darken in daylight. The third bath dissolves these salts and makes the photo insensitive to light, and therefore permanent.
Allow several minutes, agitating from time to time. Until the sheet has spent long enough in the fixer, it remains vulnerable, and only after this bath can you switch the white light back on without any risk.
Rinsing removes the chemicals
The exhausted fixer has to go, otherwise it attacks the image over time. Rinse the sheet under running water for a good many minutes, even more generously if the photo is to last for years.
Once the bath is exhausted, also plan what to do with the used fixer: keep it in a dedicated container before taking it to a recycling centre.
Then leave the sheet to dry flat or hanging, away from dust, and it is stable and can be handled in full light.
From paper negative to final positive
What you are holding at this stage is a paper negative, with lights and darks reversed: the sky comes out black and the shadows light.
Two routes lead to the positive:
- Scan the negative, then invert the values on the computer, to get the image in a few clicks.
- Contact print the negative onto a second sheet of paper, which in turn comes out inverted, and therefore positive.
When you are starting out, keep the paper negative as it is, because it already carries all the substance of the image, and this inverted rendering is part of the pinhole effect, just like the soft blur and the darkened corners that come up with it in the developer.
What developing does not do
The developer makes visible what the light has recorded, no more and no less, and it cannot rescue a bad shot. The density of the image is decided upstream, when taking the picture and through the exposure time, far more than in the trays.
When the result is disappointing despite properly handled baths, the cause is therefore to be found before developing, and the article on failed photos helps you trace it back to the right one.
Why the kit makes developing simpler
For many people, the hurdle lies in gathering the equipment and measuring out the chemicals. The Sténoflex removes this obstacle, since it supplies the developer and fixer as concentrated liquids in two bottles of 15 ml each, with instructions that give the time for each bath.
All that remains is to provide the trays, the tongs and the red lamp.
Developing is no great mystery once you understand the order of the baths, and it is often there, in front of the image coming up in the developer, that you truly catch the pinhole bug.
Éric Marais — Photographer, author of two books on pinhole photography (published by Pearson) and creator of the Sténoflex. He has run introductory workshops in pinhole photography and analogue developing from the very beginning.
