Bayard direct positive

Bayard’s process is the best argument in the course for a claim that sounds perverse: the process that made the object everyone said they wanted is the one that had no future. It gives a direct positive on paper, straight out of the camera, in 1839 — and because it is a positive, there is nothing to print from. The Part I lesson sets it among the 1839 claimants and owns the priority dispute.

The chemistry

Eder describes what it was, and it is ingenious. Silver chloride paper is blackened all over in daylight, soaked in about 4 per cent potassium iodide, and exposed while still moist in the camera. Light now bleaches rather than darkens: iodine separates from the potassium iodide and attacks the blackened silver, so the bright parts of the scene come out bright.

Read that against the same author’s account of why Talbot’s iodide fixing failed and the two halves fit together. In the presence of excess iodide, nanoparticle image silver is readily oxidised back to pale silver iodide. Talbot met that as a defect — his prints faded towards a uniform pale yellow — and published it as a reason to abandon the fixer. Bayard made it the exposure. The same reaction is a failure mode in one process and the mechanism of another, which is the most useful thing this entry has to teach, and it is why the two must be read together.

The tonal logic follows directly. Where light fell hardest, most silver was bleached, so the highlights are the areas that lost the most image. This is not printing out and it is not developing out: it is a third arrangement, in which the image substance is put down first by light and then selectively removed by light.

Historical workflow

Bayard (1801–1887) was a clerk at the Ministry of Finance who experimented after hours. The Getty Museum, which holds the second largest collection of his work, records that he began experimenting in January 1839 — the same month as both announcements — and invented the direct positive process on paper.

The chronology matters because it is what the priority dispute is argued from: specimens shown to Desprets on 5 February 1839; a public exhibition of direct positive prints in Paris on 24 June 1839, favourably mentioned in the French journals of July and August; a sealed description deposited with the Academy on 11 November 1839; publication on 24 February 1840, the same day Verignon presented a similar process.

The camera exposure was about an hour, which was ordinary for the year.

⁇Who invented the direct positive?

Four people, in two countries, inside twelve months, and the adjudication is on the record.

Bayard showed specimens privately from February 1839 and exhibited in June. Verignon presented a similar process to the Academy on the day Bayard’s was published. Lassaigne claimed to have communicated the same thing a year earlier, in L’Écho du monde savant of 10 April 1839. Fyfe described the same bleaching method to the Society of Arts in Edinburgh on 17 April 1839, using paper prepared with silver chloride or phosphate, and Eder notes separately that Fyfe fixed his photographs with ammonia.

Arago, adjudicating for the Academy on 16 March 1840, found that Verignon’s and Bayard’s methods did not differ from Lassaigne’s. Eder, a century later, agrees on the criterion and extends the list: “If priority of publication of the process is to decide whose claim is valid, Lassaigne must be mentioned first, then Fyfe, and only then Bayard and Verignon.”

What the course states. On publication dates, Eder’s order — reported without endorsing publication dates as the right criterion, because they measure access to a learned society rather than who did the work.

A second contested claim belongs here and is not settled either. Bayard’s 24 June 1839 exhibition is very often described as the first public exhibition of photographs. Eder records the event but not that description of it, and the course could not verify the superlative. It is also awkward on its face: Faraday showed Talbot’s photogenic drawings at the Royal Institution on 25 January 1839, five months earlier. Whether Bayard’s was the first public exhibition of photographs anywhere depends on what counts as an exhibition, and this atlas does not decide it.

The image

What the course can state. It is a positive on plain paper, made in the camera, with the image substance being bleached silver in the fibres. There is no binder, so it belongs visually to the photogenic drawing family: matte, sunken in, the fibre showing.

What the course cannot state. No source read here gives the image colour, the tonal scale, the maximum density or the identification signature a conservator would use. Those fields are empty in the front matter above and they are empty deliberately. A guess at the colour of a bleached silver image would be exactly the kind of invention Rule 1 forbids, and it would be a plausible guess, which is worse.

Handedness. Ware’s general rule for direct processes applies: a one-step process that puts the sensitive surface in the camera and then shows you that same surface reverses the handedness of the scene, unless the camera carried a mirror or a prism. The course has not read a statement of Bayard’s own arrangement.

Permanence

Partly solved, and the evidence is custodial rather than analytical. The image is bleached silver, contemporaries found the prints fragile, and the Getty keeps its holdings in the dark.

That last clause is a permanence statement of a particular kind, and it is worth reading as one: an institution’s storage decision is evidence about a material’s behaviour even when no measurement has been published. What it does not tell you is the mechanism, and this entry does not supply one.

Hazards

Silver nitrate and silver chloride at printing strength, handled wet, which the rubric names under Level B; potassium iodide at about 4 per cent, which is the mild part; and a sheet blackened in full daylight before the camera exposure begins, which is a working inconvenience rather than a hazard. The waste is silver-bearing and belongs to recovery.

Nothing here approaches Level D. The reason the course does not perform it is that no written part owns it, not that it could not.

Where the course teaches it

As an argument, in Part I; as a procedure, nowhere. The register assigns this row to Part I, and Part I uses it for one purpose: to show that solving the wrong problem beautifully is still solving the wrong problem. Its virtue is its defect. A positive is what everybody said they wanted, and because it is a positive it cannot be printed from — Bayard solved the third of Part I’s three problems by abolishing it.

Set the row against its neighbours and the century is in the comparison. The daguerreotype has the same defect and far better pictures. Photogenic drawing has worse pictures and the negative-positive principle. The process with the best pictures could not be copied; the process with the worst pictures could; and Bayard’s had neither advantage.

No part of the course plans a lab in it. If one were ever written it would sit beside Part XXII’s salted paper work, on the same silver chemistry and at the same level.