Cyanotypes: not as easy as 1-2-3

There is recently a growing interest in alternative processes. There’s also a growing amount of quick-starter kits that let you jump on-board such processes fast. Although I think these kits are the most recommended way to get started, be aware that getting a reasonable print is not as easy at it seems. I will try to explain ways to avoid frustration, despair and disappointment.

I will stick to cyanotypes as this is the method I have used.

No matter what the instructions in your kit of choice tell you, you will need to calibrate.

First and most important think to keep in mind. If you use the “new” cyanotype formula note that it penetrates paper dramatically more than the classical formula. The downside is that you will need a paper of excellent quality to use it, 100% cotton 300mg worked for me. It is also much more sensitive than the traditional formula so your exposure time will be shorter. On the other hand, you will get more easily deep blues and people say that it is more durable although this is debated and  I have little experience. The traditional formula stays on top of the paper and does not penetrate. It spills more easily but also can be cleaned more easily. You might use many different media but you might as well find yourself exploring the option of double coating to achieve the colors you like. Don’t look at these as obstacles. They are actually creative opportunities.

Now that the choice of chemicals and papers is made, one must understand the variables of the process. These include of course the chemicals, the papers, but also the coating method, the transparencies used for negatives, the printer inks, the printer, the reversal process and the light source. All these variables must be calibrated to some extent in order to achieve the print you want. Neglecting these may or may not give you a print you like, but not the print you want to have.

The coating method defines the thickness of the chemical on the paper. If you are going to use a brush, don’t make the mistake. Buy one without any metal parts or you will end up with beautiful deep blues but no image. “Glass” (aka transparent plastic) rods make more uniform coatings but push a lot of chemical towards the borders and trying to coat that you might make some lines around the central area. Sponge like material (e.g. “Wettex”) can also be used. I have used all methods and I have to say that for different images I use one or the other. Sometimes I like the brush strokes of the chemical or I would rather mask the paper and have clean cut borders. But never, never use any metal.

You must start from choosing the light source. If you choose the Sun, be aware that exposures can be very short and you will have to depend on seconds. Sun in some places like Greece is unbelievably robust and dependable. In Switzerland it is not. So I decided to build a UV printer. The UV printer is not difficult to build and I recommend it if you have some basic skills. It allows you longer exposure times and mistakes are almost unimportant. The Sun on the other hand is much more pleasant 🙂


Once you have chosen the light source you want to know the exposure time. What you could do is coat the paper with the chemical you are using, cut a stripe and prepare it for exposure. If you have a wooden exposure frame with a glass, cut some stripes of black paper or other material and tape it on the glass. Then add a sheet of the negative medium you are using and the stripe of coated paper in the frame. Start exposing it and remove one stripe from the glass in predefined intervals. Start with a few minutes, drop to a minute and then if needed to half a minute. This way you will get some idea of the time you need to expose your combination of negative, chemical and paper. The wedge that results will tell you that, e.g. the part of the stripe exposed for any time between 10 and 15 minutes shows no tonality. The parts exposed less than 10 minutes have tonality while those exposed between 1 and 2 minutes in 0.5 minutes interval are totally white. So now you know somehow the sensitivity of your process: expose for 8-10 minutes.

Next you want to figure out the color(s) you will use for your negatives. This is a very much debated issue. Most web sources will tell you to choose something reddish or yellowish while many people just use black. In my experience black will give very vivid contrast while reds make differences more subtle and are better for midtone images. So here you are, there’s another creative opportunity. Here’s how you choose the colors. Go to Michael Koch’s website and print the HSL Array 98. This you will do on a piece of transparency and you will flip the image if you want the inks to be as close as possible to the chemicals (emulsion down).

A word about transparencies: most people recommend using Pictorico OHP or other transparencies. The cost of these transparencies is relatively high, that is not to say that their quality does not justify the cost. I used good quality inkjet transparencies with very good results from other producers as well. Other people swear that whatever you use, if you calibrate with it, it is just fine. Next thing I will use is inkjet tracing paper: I expect it to provide better tonal range than transparencies. We will see. Whatever you use, test it to see that it suits you. If you plan to go for many negatives, or you want to experiment, choose cheaper and simpler options.

Once you print and expose the HSL array you will notice that it has large areas completely dark, others completely light and everything in between. Let the exposed paper settle for at least 24 hours. After the period of time, all tones must have appeared. Now you need to pick a color. But which? Try to find a color close to the equator in an area where going south turns gradually light, going north turns gradually dark, and left and right go either dark or light. This means that the color you choose must be in an area of monotonic tonal changes. This is not always straight forward to find and there may be many choices. What I do is pick more than one colors that look good.

Then use the ChartThrob script to create the 101-step wedges for all colors you chose plus black. I always include black and end up using it most of the time. Do the calibration procedure and create curves for all step wedges and keep them. Add a name that indicates the paper, transparency, chemical and exposure time to each curve so that you know roughly the process that produced it and how it should be used. Add actions for each one so that you can automate the production of negatives. When exposing the wedges, I also add a small image to see how it really looks like. This will help you decide which curve to choose for which image. Add a landscape and a portrait, because skin tones may need different treatment. Record all this information for your future reference.

What you have done now is that you have created some rules of thump that will let you know how an image will be printed. One could use the reverse process to create a transformation curve that, once applied to a B&W image, would give a good indication how it would look in cyanotype. Good task for the future.

3 thoughts on “Cyanotypes: not as easy as 1-2-3

  1. Hi, I really liked your blog. Just finished reading about the cyanotype process, Where do I get the chemicals for the process in Geneva or nearby? Thanks.

  2. Hello!

    Good article thank you so much for all the informations you provided.

    Anyway I’ve a problem downloading the Michael Koch’s HSL Array 98 because the site is dead. I’ve also done a search with google to find an alternative download with any success.

    Can you please provide me the file or an updated link where I can download it?


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