One of the most common questions I am asked is about 'my darkroom'. I always reply that I don't have one because I don't need one. This often comes as a surprise. I then explain that the most important processes that were used by the Pictorialists used the sun to expose their images. I explain these processes in more detail in my blog about the history of these processes and a blog outlining the modern versions of these processes I use now.
Nowadays we not only know much more about the spectrum but also the bulbs to produce the necessary frequencies are readily available. This gives us great freedom to design lightbox to be used inside and because we can now avoid the light frequencies to which the processes are sensitive, we can actually work in a room that is quite bright. It is called a dim room. Most of the Pictorialist processes require a light source that emits much of its radiation in the Ultraviolet A (320-400nm) range, which can easily be avoided.
During the day I work with the curtains fully open, just making sure that there is no direct sunlight in the room. In the evening, I use the overhead light and a desk lamp as I would do normally. I use the good old-fashioned filament bulbs - I try to avoid LED and fluorescent lighting because there can be some UV in them
Using filament bulbs I suspect would have been approved of by a great photographic inventor, Sir Joseph Swann, because not only was he part of the development of the carbon transfer process, patenting it in 1864, he also went onto invent the filament bulb and was a very successful and direct competitor to Thomas Edison.
My own UV light source is constructed on the underside of the workbench I use to prepare the papers. I designed and built both the workbench and light box myself. The lightbox uses industry-standard black-light blue (BLB) strip lights and I have four pairs mounted 140mm above the shelf for the prepared papers and negatives. The whole thing, workbench and all, cost me less than £250.
The BLB lights have a sharp peak at 365nm (from about 340nm to 400nm) - which is perfect for the alternative photographic purposes as discussed excellently by Sandy King, and it has a maximum sensitivity at about 350-420nm - almost perfect. With this arrangement the exposure times I find work well are between 7 and 15 minutes. I use a glass plate to hold my negatives onto the sensitised paper, which works well, and I live with the fact that approximately 95% of UVB is absorbed by my plate glass. However, I find I do not have to wait too long for my prints to be fully exposed and I use the time to clean up my brushes and syringes.
It is generally agreed that these light frequencies an enlarger would not work and so we all use negatives that are in direct contact with the prepared surface. I'm not fully convinced that enlargers won't work - but I do enjoy my large negatives, they are a joy in themselves
The Pictorialist processes are also highly sensitive to Ultraviolet B (280-320nm) but I void this using the BLB lights. This may increase the exposure time slightly but it avoids UVB and the skin cancers and cataracts it causes.
List of Dim Room Equipment
A rough list of what you will find in my dim room on most days is:
BLB light box with guide with plate glass and timer
Set of weights and glass plate. I don't use a vacuum to keep the negative on the paper, I use a sheet of heavy glass with a weight on each corner
Epson Stylus Pro 3800 - I can print up to A2+. This lives under the desk as well
My immediate chemistry cupboard, with ammonium dichromate solution (my favourite), potassium dichromate solution and ready-made gum arabic
Brushes, measuring syringes, mixing bowls and plates
Boxes of powdered pigments - my favourite supplier is Cornelissen & Son. I do a lot of white printing and I am sure a kilo of white powder worries the neighbours
A range of watercolours - I always use the best watercolours I can find. My favourite are the Professional Watercolours from Winsor & Newton
Weighing scales down to 0.01g
Rolls of colour separation film for the negatives (and positives) - my favourite is PosiPrint™ Screen Film 130mic from Colourbyte, the 432mm wide fits my printer well and comes in a 30m roll
A rotary A3 guillotine to cut the film
Pens, markers, erasers and a spatula for the powdered pigments
And all too rarely at the moment - me
Currently I do not keep my paper store in my dim room and finished print are also stored elsewhere. I prefer not to wash or develop in the dim room, similarly the drying facilities for the final prints are not in the same room