It is almost a month since I reported on my participation in a contemporary salt print workshop. Keen to put what I discovered into practice I’ve been gathering together the bits and pieces I would need that I don’t already have and also gathering images that I imagine would look good when printed on salted paper.
The weather over the past couple of weekends has been favourable so I’ve been out and about with my Intrepid field camera and have a good selection of 5×4 negatives to print from. The ‘contemporary’ process takes a scan of the original negative and with some editing in Photoshop produces what should be an optimised digital negative from which to make the final print. The digital element of the process has the added advantage of producing a digital negative of a size larger or smaller than the original and also means that the source image can be from a digital camera.
A few months ago I had been gifted a quarter-plate contact printing frame and saw my salt print experiments as an ideal opportunty to use it, so I would need to reduce my 5″x4″ negatives to 4¼”x3¼”. However, I don’t use Photoshop so first I had to rewrite the workshop instructions for what I do use, Serif Labs Affinity Photo – Basic digital negative preparation in Affinity Photo. The exposure time would be determined by a test strip to identify the exposure required to achieve maximum black. For maximum control of the highlights, in Photoshop / Affinity Photo and curve to create a denser negative together with a colour screen are applied. The instructions refer to a generic colour screen, which I used for this exercise, but in the workshop we created custom values by exposing a colour spectrum, processing the result, then finding the colour that equated to the brightest highlights.
I can’t say I fully understand the colour screen step and so I started off by picking an image from which I created four digital negatives, one as unscreened greyscale, and the other three screened with varying RGB values: 255:50:0, 50:255:0 and 25:50:0. These are shown below together with the print made (spot the schoolboy error – I overlaid captions on each negative but forgot to flip them!). The four were exposed and printed as one so the only variable affecting the print is the colour screen applied to each digital negative.
My darkroom space is rather limited (its primary function is a shower room) and has to be set up according to the needs of the process being undertaken. For salt printing, the preparatory function of cutting paper to size and coating it with a 2% sodium chloride solution could be performed elsewhere. However sensitizing the paper with 12% silver nitrate solution and processing the exposed paper have to be carried out under safelight conditions. Exposing the paper can be carried out either under the controlled conditions of a UV light source such as my adapted face tanning unit, or under sunlight ideally with a UV index of at least 4. Here in Scotland that amounts to a couple of hours either side of mid-day during the summer months … if we’re lucky! However it is to be exposed, the sensitized paper has to be kept in the dark until ready for exposure.
For my screening-test negatives I had my UV unit set up in the darkroom alongside my processing trays with just a small working area left to sensitize the salted paper with silver nitrate. This gave me a number of problems: the small working area, the wait in the darkroom for the sensitized paper to dry and once the UV unit was on I realised that the inevitable light leaks from it would potentially fog any other sensitized paper whether awaiting exposure or in the process of development. For the test, I was working with only one piece of paper but I would need to rethink my setup for making a series of prints.
I knew that to make any reasonable assessment of my test I would need to allow the print to dry down overnight so I stored my processing solutions (3% sodium chloride and 10% hypo fixer) in light- and air-tight bottles, restored the shower room and went off to sleep on a solution to the darkroom layout.
From my test I decided to stick with RGB values of 255:50:0 and set about creating fifteen digital negatives. I laid them out five to a sheet of Permajet inkjet transfer film with the layout such that I could easily cut out the individual negatives.
I decided that this time I would set up my darkroom for safelight operations only and have the UV light box just outside in subdued light. I reckoned that a little exposure was inevitable but probably of negligible effect (and with hindsight I was right!). When I explored making dry glass plates about a year ago I had aquired a small shallow-drawer unit for drying the emulsion-coated plates and decided to use it as storage for the sensitised paper as I waited for it to dry. This way I could sensitize paper for the session then clear my work area of silver nitrate solution, pipette and brushes.
For the screening test I had run a test strip to determine an exposure time of 5½ minutes and decided to use that as a starting point. The only difference would be that the screen test was done in a 10″x8″ ‘modern’ contact printer while this session I would be using a vintage quarter-plate printing frame with much thinner glass that sat about 1cm further below the UV light tubes. I was also a little uncertain as to how my hypo solution would have fared from being stored overnight as it does not have much ‘shelf-life’.
Processing one image at a time (I have only one contact printing frame!) the first few prints came out of the UV light looking very dark and overexposed. That was to some extent to be expected and they would lighten up as they were processed through the salt bath and hypo fixer before rinsing. However they did not lighten up as much as I would have expected or wanted and so I reduced the exposure time as I worked through the negatives, down to five minutes, then four and a half and the final images just four minutes.
The colour of the prints changes as the process progresses and ultimately as the prints dry down they take on the typical sepia tone that I would expect. There’s a bit of bronzing to some of the prints which is likely due to the age of the fixer and inconsistencies in fully covering the paper when coating are apparent. I consider these all marks of individuality and a part of the image!
What I’m not too happy with is the loss of shadow detail in my prints. I suspect this is due to the curve I have applied when creating the digital negative rather than to the UV exposure given. When creating the digital negatives I adjusted the curve as I would for a ‘normal’ image whereas a negative for salt printing needs good shadow exposure and detail, does not need to be high contrast and needs sufficient density to allow silver chloride to change into metallic silver during exposure. If I have failed in creating the prints I had expected I suspect that this is the area in which I can make the most improvement. That said, for a first attempt under my own steam, the fifteen prints I made do have a ‘look’ and a ‘feel’ that I like.
I coated and sensitized three more pieces of paper than I used. These lay in the drawer shaded from light ready to be forgotten about. However as I type up my exploits a day later, the sun is shining and according to the BBC the UV index should be about 3. Surely worth a try to see what an exposure to sunlight might do. I selected three of my favourite images, made up some fresh salt bath and hypo and exposed them one at a time for fifteen minutes each. Here’s how they look now that they’ve dried down a bit.