Blotchy kallitype development

Owned by Break/Fix — the iron-silver print that would not clear, whose fifth case names this entry and gives the discriminator by shape: hard edges mean liquid, and in a kallitype the liquid is almost always the developer, so any part of the sheet that starts a second late shows it. That page adds the two causes that produce the same appearance more slowly — a cold developer where a warm one was specified, and an exhausted one — and separates a soft directional streak as a coating fault instead. Printing a kallitype owns the pour. This entry was built earlier from Part IX’s work on uneven development.

What you see

Patches, and often a hard-edged mark shaped like the way the sheet went into the tray. Bostick & Sullivan call them watermarks and put the cause in one clause: “Image will appear immediately so this must be done quickly, or else watermarks may appear.”

The pattern is the diagnosis. A mark shaped like a wave front, a corner, or the line where a sheet buckled, is an immersion fault. A general mottle with no geometry is a coating or absorption fault. A print that is uniformly weak is neither.

Likely causes

1. The sheet entered the developer unevenly. On a process where the image appears at once, a second’s difference between one corner and another is a second of development.
2. The developer was too cold. Photographers’ Formulary’s black-tone and brown-tone developers work best warm, around 38 °C (100 °F) or higher; only the sepia-tone developer is a room-temperature bath, and it runs for ten minutes rather than five.
3. The sensitiser was unevenly absorbed. Ware’s paper-problems argument applies to every iron process: if the sensitiser sat in the coarse pores rather than in the fibres, the developer meets different amounts of it in different places.
4. Too little solution, or too small a tray, so the sheet could not be covered in one movement.

What is happening: the chemistry and physics

The kallitype gives almost no print-out image, which is the first thing that makes this process unforgiving. Bostick & Sullivan say so directly — there is little print-out image, so timing has to be found by trial and error or a test strip — so the printer has no visual check between exposure and development.

And then the whole image arrives at once. In a developing-out silver gelatin print the image builds over tens of seconds and small differences in wetting even out; here it does not. Every part of the sheet that meets developer at a different moment is at a different point in a very fast reaction, and the difference is fixed into the print.

Temperature multiplies the effect. Development is a rate process — Part III owns the kinetics — and the Formulary’s own instruction to run the black-tone developer at 38 °C or above says how much rate this particular bath needs. A cold bath is a slow, sluggish bath whose behaviour differs across a sheet that is not evenly wetted, and a hot one is a bath in which a moment’s delay costs more.

Underneath both is the coating. Ware’s point about the iron processes is that the sensitiser must be absorbed into the interfibrillar space within the surface cellulose fibres; where it merely sat in the pores, there is less of it to develop and it is more easily displaced by the incoming solution.

!The confirming test: immerse a blank sheet the same way

Coat, dry and develop a sheet that was never exposed, using exactly the immersion technique you normally use. There is nothing to develop, so anything that appears is chemistry meeting paper unevenly rather than light meeting silver unevenly.

Then change one thing at a time:

• Slide the sheet in face down in one continuous movement, and agitate at once. If the marks go, the fault was immersion.
• Warm the developer to the stated figure. If the marks go, the fault was temperature.
• Coat the next sheet with a surfactant, or work the surface until it loses its gloss. If the marks go, the fault was absorption.

And use the same tray and volume every time while you are testing, because a sheet that has to be pushed under is a sheet that develops in two stages.

Diagnostic questions

• What shape are the marks? Geometry points at immersion; no geometry points at the coating.
• What did the thermometer say? 38 °C or above for the black-tone and brown-tone developers on the Formulary’s own sheet.
• How much developer, in what tray, for what size of print? Enough to cover the sheet in one movement, with room to agitate.
• Which developer? The three in the kit behave differently — more Rochelle salts for sepia, more borax for black — and the sepia one is a slower, cooler, longer bath, which is more forgiving of this fault.
• Was the sheet dry when it went in? A partially dry coating develops differently from a fully dry one.
• Was dichromate added, and to what? The Formulary are specific that contrast is raised by adding 5 to 20 drops of 10 per cent potassium dichromate per 500 ml to the mixed developer and not to the sensitiser.

Corrective action

Re-print. There is no rescue for a print developed unevenly, because the unevenness is the image.

Change the immersion first, because it is free and it is the cause the supplier names.

Bring the developer up to temperature, and check it rather than assuming it.

Then look at the coating if marks persist without geometry — the same tests as blotchy and streaked hand coating.

Prevention

One movement, face down, agitate immediately. That is the whole technique, and on this process it matters more than on any other in the course.

Enough solution and a big enough tray. A sheet that has to be persuaded under the surface is a sheet with a watermark on it.

Hold the temperature the developer was written for.

And remember what comes next: the kallitype bleaches in the fix, so tone before fixing or over-print by a stop or two — which is the fixer-bleaching entry, and a fault it is easy to acquire while fixing this one.