Cyanotypes

At the time of writing this, it was less than two months ago that I produced my first cyanotype print. Since then, I feel I've learnt a lot and decided to document that here for the benefit of any other beginners. When I started, most of the information I found assumed a certain amount of knowledge already, for instance, assumptions that you knew 'how' to coat the paper, and skipped over many of the details. Here, I'm planning to document everything and assume the reader knows nothing, which is how I was when I started.

I ought to say now that my method involves using the 'new' cyanotype process created by Mike Ware. Some people don't like it but it works for me. If you are looking for details on the original cyanotype process, then you may want to look elsewhere. My method also includes the use of digitally created large format negatives rather than large format originals or large format copy negatives - so you won't find any information here on those techniques either.

I started out by buying the Fotospeed cyanotype kit. I can't recommend it. It's expensive for what you get and the quality of the materials is dubious. I had problems with both the paper supplied and the OHP material supplied for making the negatives. Also, the 'glass' rods supplied are not glass and I had problems getting an even coating of sensitiser on the paper with them. It did, however, get me started and is an option.

Here's the first (the very first) print I made...

...note the uneven coating and the marks on the surface of the paper. The same marks (exactly in the same place) were on another sheet of paper so I think the paper was damaged in some way.

As my first attempts weren't great, I asked around to see what other people did and what materials they used. As a result I bought some more paper, more OHP material and a brush to coat the paper with and started again.

Below is the method I'm currently using. I'll update this if I find better ways of working.

Equipment and materials

Paper: Bockingford NOT 200lb.
Sensitiser:
Citric acid:
Brush:
Small syringe:
OHP material:
Printer:
UV exposing unit:
Timer:

Making the negative

Making a suitable negative has, for me, probably been the most troublesome. It took some time and a lot of experimenting to find the right combination of paper/printer settings to get it right. Also, I found the negative needs the tonal scale distorted to get a realistic looking tonal scale in the final print. I'll relate the problems I had and the solutions I found as it may help others to go through a similar process, but, unless you are using the exact same printer and materials as I do, the settings I use probably won't work for you.

In it's simplest form, making a digital negative involves creating the image on the computer then printing it out in negative form onto overhead projector (OHP) transparency material. You will almost certainly find, though, that the tonal scale is distorted in the final print requiring some deliberate distortion in the original image to compensate. The easiest way to deal with this is to make a print from an image that contains a full range of tones. Once the print is dry, compare it to the original and decide what parts of the tonal scale need adjustment. Make an adjustment curve that you think will give the right amount of correction and save it. Apply the curve to the original image and then make another print. It may be necessary to do this two or three times, modifying the saved adjustment curve a little each time, but it should be possible to get a reasonably good result this way. Once a satisfactory adjustment curve has been made, in future, apply it to every image just prior to printing.

A step wedge. Right click here to download a large version.

In my case, after going through the process of creating an adjustment curve, I realised I had an issue where the highlight end of the tonal scale still had a major distortion that I didn't seem able to correct for. At first, I couldn't decide where the problem lay so investigated it using a step wedge. I find the best way of determining what is being done to a tonal scale is by starting out with a digitally created step wedge. As it's created on the computer, I know the each step is of equal size and the ends of the scale exactly match the black and white values of the computer. What I found was that my printer was laying down a large amount of ink for maximum black (white on the print) which was making the density of those areas of the negative considerably higher than areas that were not quite maximum black. The printer also seemed to be adding it's own distortion to the tonal scale as some of the steps in the step wedge were merging together. After much experimenting, I resolved the issue by switching the printer to a different paper type. This, however, meant I had to go through the process of defining an adjustment curve again.

Coating the paper

Put the paper on a flat surface some place where it's not going to matter if you spill some sensitiser and somewhere where you can block out any UV light. I use a large developing tray and put the paper in that so that any spills are contained. You don't need a darkroom as such, just one where any UV can be blocked out. Any room at night illuminated by a low wattage incandescent lamp is fine. If you do it in the daytime then a blind up at the window will probably suffice - that's all I use.

Dust off the paper before coating it to remove any loose dust. A can of air can be used or a clean, dry, paint brush. Put the negative on the paper and lightly mark in pencil the area that needs to be sensitised. If this is the first one coated and the hake brush is dry, wet it with water then dry on a paper towel so that it is just damp. With a small syringe, draw up the required amount of sensitiser from the bottle. I find 2ml is plenty to coat an A4 area. Release the sensitiser from the syringe a drop at a time, spreading the droplets around the paper. Now use the brush to spread the droplets and evenly cover the whole area that requires sensitising. It might, at first, seem that the brush has soaked up all the sensitiser and there is insufficient to cover the area, but keep brushing and the brush will give up the sensitiser it's absorbed. Only brush lightly - don't put any pressure on the brush more than is necessary to keep it in contact with the paper. Too much pressure and the paper surface may be damaged. Once the sensitiser has covered the area, continue to brush first one way, then at right angles, using the lightest possible touch, until the sensitiser looks even with few brush strokes showing.

Put the paper in the dark to dry. It only takes a matter of minutes and I don't find forced drying to be any advantage.

Exposure tests

The amount of time required to fully expose the paper is the time after which no further increase in density of the shadow areas is apparent. The best way to determine this for any particular setup is by exposing a sheet of sensitised paper by increasing amounts, developing it and then checking to see at what point no further increase in density occurs. My initial attempts at cyanotype printing suggested I needed an exposure time of around six minutes so I did a test using exposures of 3 to 8 minutes.

When doing the tests, use a blank sheet of OHP film over the paper and set up the light source exactly as it will be when making a print exposure.

Exposing the print

Work in a darkroom or a room illuminated by a low wattage incandescent lamp.

The negative needs to be kept into close contact with the paper. I find the best way of achieving this is to use two pieces of glass. Place the paper on one, the negative on top, then the second piece of glass on top of that to keep everything flat and in close contact. The top piece of glass, obviously, needs to be kept clean or dust marks can show on the print. Some people use purpose made contact printing frames to hold the paper and negative. The advantage is that the frame can be opened part way through the exposure to check the print without the paper and negative becoming misaligned. I don't think this is of any benefit if you are using a constant light source as the exposure is determined by time and not by inspection.

Having set the paper and negative in place, set up the light source to give an even exposure over the whole sheet of paper. Expose for the time determined by your exposure tests.

Development

I first wash the print in cold water to remove the unexposed sensitiser. I wash the print in a developing tray placed under a running tap. The water becomes discoloured very quickly and I empty the water fom the tray frequently to prevent the paper becoming stained. Once the water is running clear, I drain the water from the tray and put in a solution of citric acid. I use 20g to 600ml of water and use it for, usually, no more than three A4 sized prints. The citric acid becames discoloured quickly and I don't like to use it once it becomes too coloured in case it stains the paper. I wash the print in the citric acid for about two minutes, then empty it out and wash the print with running tap water again.

All the instructions I've read suggest the citric acid will clear the highlights of the print. But it doesn't seem to for me. The first few prints I did had highlights that were still very blue. Extended washing after the citric acid helped a little but not much. However, I discovered by accident that washing the print in hot water has a bleaching effect and does a very good job of clearing the highlights. Some loss of density in the shadows also occurs but not much and hot water washing is now my standard method of working. To get the highlights of the print just right, it helps to have an area of pure white in the print (I put a white border around mine and this serves the purpose) which you can use to judge how much to wash the print. Once the white area becomes as white as the unsensitised paper, it's enough. It's possible to stop short and allow the print to dry then, if necessary, wash the print again to finally clear the highlights.

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