Duotone cyanotypes #6 – Print the first layer

Part 6 in Matthew Bary’s series Duotone cyanotype with detailed instructions for the penultimate step in the due-tone cyanotype process, including preparing bleach and toning solutions, exposing the print, developing, bleaching, and toning the paper.

Writer and photography / Matthew Bary

A continuation from the previous article Duotone cyanotypes #5 – Shrink the paper. Text

Making the first layer!
This is the second to final step for this due tone process and it is going to have quite a few steps, but the payoff in seeing the print in the last step is worth it. So let’s start with a list of items needed. You will need:
  • a tray to develop in
  • a large tray or tote for rinsing throughout this process
  • a tray to bleach in
  • and finally a tray to tone in.
I use cheap baking pans and shallow plastic totes. Do not use aluminium pans only non-stick coated ones or just stick with shallow plastic totes to be sure. You will need UV light to expose your layers, I use an 80-watt UV-led floodlight, which can be suspended or set on a simple frame made of wood to hold it around 8” from the negative.  You may need to go higher depending on the light. Do not get too caught up in what kind of UV light to use. I have even used large royal blue and very high power white and they all worked fine, just use longer exposure times.
UV exposure unit using a flood light.
UV exposure unit using a flood light.
You will also need two pieces of glass to hold the negative close to the paper. If you suspend the light you will have to use some sort of clamps to hold the glass together but if you use a simple wood frame to hold up the light. Its weight plus the frame will hold everything in place. You will need washing soda “Sodium carbonate”. Do not use ammonia for bleaching citrate-based cyanotypes.
Set everything out for the final steps of cyanotype duotone.
Set everything out for the final steps of duotone cyanotypes.
It is also helpful to have litmus paper to get the pH right in the bleach bath. You will need a toner, I use pure tannic acid but a strong green tea would work as well. You could potentially use other types of tea but it will change the outcome of the final print, tannic acid and green tea are pretty much identical.
We are going to expose, develop, bleach, and tone all in the same instance instead of drying the paper in between each step, this reduces the time needed to complete a print. Before we do anything we must prepare our bleach bath and toner to get everything ready to go right after the exposure is done. 

Make the bleach solution

You will want your solution to have a pH of 11-12, I start by dissolving a tablespoon of washing soda into a few cups of hot tap water and dissolve it well, then pour it into the bleaching tray but make sure anything that did not dissolve does not get in the pan.
Make the bleach solution
Make the bleach solution – dissolve a tablespoon of washing soda
Make the bleach solution
Make the bleach solution – stir until you reach the 11-12 PH,
Next keep adding cold tap water and stir until you reach the 11-12 PH, you may have to keep adding water and if it will not hold any more just dump some of the solution out then continue to add cold tap water until you reach the optimal PH. Always use cold tap water at this stage as the warmer the bleach solution is the faster it will bleach and we want it to bleach slowly, this retains more detail.

Mixing bleach Mixing bleach Mixing bleach

Measure ph
Add water until you reach the optimal pH
Always use a fairly deep pan to allow sediment to fall to the bottom and not touch the print, at this stage allow the solution to sit and settle while you move on to the next step.

Make the toning solution

Use a fairly deep pan and two bottles or another type of container to keep the print submerged. In a couple cups of hot tap water add a heaping spoon of tannic acid and stir in well.
Mix tannic acid
Mix tannic acid

Mix tannic acid

Tannic acid is very difficult to dissolve all the way and requires a lot of stirring, you can also use an electronic stirrer if you have one available. If you were going to use green tea at this point just fill a 4-cup container with green tea bags “about one for every cup of solution” steep then remove the tea bags. In either case, after you are done dissolving or steeping pour the contents into your toning tray add enough cold tap water to fully submerge the print and stir it well. Over time the solution will get darker in color, this is normal.
Mixing tannic acid to tone cyanotypes. Mixing tannic acid to tone cyanotypes. Mixing tannic acid to tone cyanotypes. Mixing tannic acid to tone cyanotypes.
Make sure your large rinsing pan is full of water and we can now get onto the exposure. I always brush off my glass with a large soft paintbrush to remove any dust etc. Lay your paper down either on a hard surface or a piece of glass making sure the emulsion side is facing up, then place your negative “print side down” onto the paper. The printed side is darker than the non-printed side. At this point just make sure the negative is fairly squared with the paper but it will be more critical in the second layer.  Depending on your setup, place a piece of glass onto the negative then the frame to hold the light up and finally the light. If you suspended the light place the paper and negative between two pieces of glass and clamp them together.
Coated cyanotype paper Coated cyanotype paper

Expose your print

You can either use a timer wired into the plug or just time it with a stopwatch, both layers will have about the same exposure time but you may have to do some test strips to figure out what the optimal exposure time is. In this case an 80-watt UV lamp at about 6” on an 8×10 negative timed out to be 65 minutes. Now that the exposure is done you can remove the lamp, glass, and negative and you should see a latent image.

Expose your cyanotype Expose your cyanotype

Expose your cyanotype
Expose your cyanotype. I use a flood light.
The latent cyanotype image.
The latent cyanotype image.

Develop your cyanotype

Now a little bit on developing cyanotypes. You can develop a cyanotype:
  • in cold tap water and you can develop
  • in hot tap water,
  • in neutral PH
  • in water with vinegar or citric acid

To make it simple cold = longer exposure and higher contrast. Hot = shorter exposure and lower contrast. Neutral PH = longer exposure and higher contrast. Acid = faster exposure and lower contrast. Below you can see the difference between the first image that has been acid-developed, and the second one from plain cold tap water:

Acid developed cyanotype
Acid developed cyanotype
Water developed cyanotype
Water developed cyanotype
Now here lies the issue, this will also affect the bleached and or toned layers on a cyanotype, while acid makes a much more lively blue it also makes a yellow bleached layer very dull as well as a tannic toned layer look almost black, and while an alkaline bath will make a tannic acid layer look very strong red and a yellow layer bright yellow it will also turn a blue layer into a dull purple. So the trick is how to balance the two. I just use plain cold tap water to develop and maybe a little warm water to rinse and that seems to work well.
After you are done exposing your cyanotype place it in your developing pan/tray and run some cold tap water on it. Turn the pan from side to side and let it fully develop, the water will turn yellow as the unexposed solution washes off, dump it out and replace with clean water, repeat this a few times until the water looks clean and there is no yellow residue on the print.
Rinse the print Rinse the print
After it has been thoroughly rinsed it can now be bleached. Start by dipping the print in the bleach bath taking care not to drag any sediments from the bottom, then carefully place the print side down into the bleach bath making sure there are no bubbles under it “ will show up as blue spots”. Leave the print for several minutes, usually 30 or longer and check on it from time to time. It will have a bright yellow color when it is done. Another thing to note is the reason you must place the print side down floating on top is that as it bleaches it reacts with the water and a fine powder precipitates down to the bottom of the pan, we do not want that getting on the print.
Bleach the print Bleach the print Bleach the print Bleach the print
After it is done bleaching take it out of the bleach bath rinse it under the tap then soak it in the large rinsing tub until you are ready to tone it. Make sure to rinse thoroughly to remove all of the bleaching solution.
Rinse again Rinse again
After the print is bleached and rinsed it is time for the toning step. This step like the bleaching step has to be done carefully to avoid bubbles forming as this will leave spots on the print. Start off by dipping your print in the toning solution and pulling it out a couple of times, then using two bottles or jars filled with water carefully submerge the print to the bottom of the tray and use the bottles or jars to hold it in place. This will help keep bubbles from forming.
Keep it in the bath Keep it in the toning bath Keep the cyanotype in the toning bath Tone cyanotype in tannic acid
Leave the print submerged for 10-25 minutes or more. The more prints you tone the more the toning solution will deplete and get darker, this is normal but keep in mind that this will require you to leave the print in the toner longer. Also just be aware that the longer a print is toned the more staining you will see in the paper so not too long but just enough. When the print is done toning it will be fairly obvious that it is ready.
The toning is almost done The toned cyanotype layer is done 
The next step is very important, rinse rinse rinse. You want to get all of the leftover toner out of the paper to prevent staining on this layer and to prevent it from interacting with the second layer before the exposure is done. Pull the print out of the toning solution and rinse under cold tap water, then soak in the rinsing tub, you will also want to agitate it flip it around and even change the water out if necessary.
Toning cyanotypes toning layer
Now we have one final step before drying. After the rinse bath dip the print back in the bleach bath a couple of times and carefully lay face down in it like you did for bleaching, leave for a few minutes then take the print out and rinse under a cold tap then repeat the soaking and rinsing steps from before. The reason for this step is that it seems to help prevent an interaction when applying the second layer. When you add the second layer it will go slightly green but without proper rinsing of the paper and a brief soak in the bleach then re-rinsing it can get so bad that it will permanently stain green. This is an interaction between the wet cyanotype solution and the tannic acid on the paper. A stronger citrate solution makes this problem worse but will be addressed in the last step. You will notice in this step that the print turns a redder color as the tannic acid reacts with the bleach.
Finally, take the print out of the rinse water and hang it up to dry. At this point, you can use a fan and or dehumidifier as you will want the print to be very dry before adding the next layer. It can be stored after all of this and the second layer added at any time.

The complete series


Matthew Bary is a self-taught photographer (spending more time on printmaking than actual photography). He got into alternative photography five years ago and is amazed at all of the processes and innovations done with very old techniques. Matthew Bary lives in Corydon, Indiana, USA and often photographs his local surroundings.

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