In part 5 of our cyanotype series, Caroline Roberts takes the chemigraph process one step further by layering traditional contact prints over chemigraphs. Building on earlier experiments with chemical ratios, additives, and transparency exposures, she explores how combining two exposures on a single sheet can create complex, textured images. Roberts shares her detailed workflow – from soaking and coating to re-exposing and managing contrast – and discusses common pitfalls such as bleaching and tonal imbalance. Through testing dilutions, acid baths, and different negatives, she demonstrates how these double exposures merge abstraction and imagery, expanding the expressive potential of the cyanotype process.
Read the MSDS (Material Safety Data Sheet) before attempting to use chemicals and use the correct safety equipment.
In the previous articles in this series, I’ve covered dilutions and ratios of the chemistry in Going Beyond Blue to Explore Cyanotype Variables: Dilution, Exposure, and Moisture; adding other chemicals in Working Wet: Techniques and Effects in Super-Wet Cyanotypes; the super-wet chemigraph process in Introducing Chemigraphs: Abstract Cyanotypes with Added Chemistry; and an option for using transparencies with the chemigraph in Combining Cyanotypes, Chemigraphs and Transparencies. In this article we look at layering a traditional contact print over a chemigraph and some of the issues that can result.
For Daybook, I wanted to combine text with chemigraph exposures in a more layered way. To achieve this, I first exposed a chemigraph outside. After the print was fully washed and dried, I recoated the paper with standard 20/8 solution and exposed the second time with transparencies in my UV unit.
Step by step process
See part 3 on the super-wet cyanotype (chemigraph) for images of each step.
- Soak your paper, submerging it fully in clean water for 10-15 minutes.
- Briefly blot the paper to remove excess water.
- Put the paper on a flat surface and use a hake brush to coat the paper.
- Add the additional substances – water spritzes, salt, rubbing alcohol, and washing soda.
Coated with salt added 5. Exposure – outside for clearer marks, after drying in a UV unit if a more blended look is desired.
20/8 with salt, dried then exposed in a UV unit (2 hours) 20/8 with salt, exposed outside from wet (2 hours) 20/8 with salt, exposed in a UV unit from wet (5.5 hours) 6. Wash and dry completely.
7. Coat the dried paper with the standard 20/8 or 10/10 solutions. Allow to dry in a dimly lit or dark area.
8. Place your transparency and sandwich the paper and transparency in a clip frame. I use a simple glass clip frame with some felt to improve the contact and large binder clips to hold everything together.The paper and negative sandwich ready to go in the UV unit (this one is with the negative adjusted for vandyke brown 9. Expose for the same time as you would expose any other transparency, either outside or in a UV unit.
10. Wash and dry completely.
Pitfalls & Workarounds
1- Contrast between the two layers
The first chemigraph needs to be light enough to allow the second exposure to stand out. However, it is possible to partially bleach that first exposure in weak sodium carbonate if it comes out too dark. The dilutions I tested were 5/2 (20/8 diluted 1:3 with water), 10/2, and 5/8.
The 5/8 dilution was initially too dark for a second layer, so I bleached it a little in sodium carbonate. I gave it a brief acid wash after the bleach bath to make sure that the paper was neutralized before the second coating and exposure.
2- Bleaching in the second wash bath
Washing the paper twice can cause bleaching if your city water has a high pH, like mine. Some ways to avoid this are to set an alarm for the wash time – I keep mine under 10 minutes. The three dilution examples above all used a strict 10-minute water wash for each exposure.
Another option is to use a short citric acid wash bath with the second exposure. I use 30 seconds in a bath of one teaspoon of citric acid to one litre of water. The acid wash has the advantage of increasing the depth of tone. This example piece, in which I accidentally used a text positive instead of negative, shows the difference between a 10m water wash, a 30s acid bath followed by 10 10-minute water washes, and a 20-minute water wash. You can see from the image below that the extended second wash, of 20 minutes, has already caused some bleaching.
3- Negatives
As with the dried chemigraph with contact print process explored in article 4 {LINK}, higher contrast negatives (such as text or a Vandyke Brown negative) give clearer results.
The 5-part experimental cyanotype series
In this 5-part experimental cyanotype series, Caroline Roberts explores how variations in dilution, exposure, and moisture can expand the creative potential of cyanotypes. Based on her research and studio practice, the series focuses on material and process-based experimentation beyond traditional methods.
- Part #1 – Going Beyond Blue to Explore Cyanotype Variables: Dilution, Exposure, and Moisture – introduces her initial experiments – systematically varying wet, dry, and soaked paper conditions, as well as chemistry dilution and exposure settings – to establish a base for further testing.
- Part #2 – Working Wet: Techniques and Effects in Super-Wet Cyanotypes – explores what she calls the “super-wet” cyanotype: highly fluid chemistry used to create photograms with differing object weights and absorbency, but without adding other chemicals.
- Part #3 – Introducing Chemigraphs: Abstract Cyanotypes with Added Chemistry – focuses on chemigraphs – abstract works created by introducing reactive materials to the cyanotype mix, altering colour and texture during exposure and development.
- Part #4 – Combining Cyanotypes, Chemigraphs and Transparencies – details her process for combining dried chemigraph surfaces with simple transparency overlays, particularly text-based elements used in her publications Memoranda and Daybook.
- Part #5 – Cyanotype Layering: Chemigraphs Followed by Contact Prints – looks at combining these approaches – layering chemigraphs and transparency cyanotypes through multiple exposures and different coatings – to create complex, multi-process images.
This series is both a visual record and a technical resource for artists working with cyanotype, offering practical insights and encouraging further material investigation. To get notified when cyanotype articles are published, subscribe to the Cyanotype Newsletter.
Rated 10 - based on 1 vote
Rated 9,46 - based on 182 votes
World Anthotype Day
World Cyanotype Day
Hi David F,
For the wash baths I mean 30 seconds in the acid wash followed by 10 minutes in the water wash. The fading from 10 to 20 minutes isn’t massive, but I have left a print for an hour (I forgot about it) and the bleaching was very strong!
I’m glad that the dilutions/ratios part is clicking and making sense for you. I will work on an ‘addendum’ to the series that goes more into the details and the math of the ratios.
I had an ah-ha moment last night about the 20/8, 20/10, 5/2, 5/8, etc numbers:
1) this not only tells the ratio of A to B but also how much of each is mixed with 100 L of water. So, these numbers are telling us ratios and dilution rates. Ex. though the “ratios” of 20/8 and 10/4 are the same, the second one is way more diluted.
2) Most of the formulas I found – including the Jaquard, Christine Anderson and Malin % Gary Fabbri recipes are all 40 g Potassium Ferricyanide in 400 ml water; and 100 g Ferric Ammonium Citrate in 400 ml water – though I think Jaquard mixes up what they refer to as A and B. But then again, Ms. Anderson mentions other ratios as being her favorite for certian papers.
Ultimately, it’s the notion of experimentation – with ratios, dilutions, chemistry, substatnces, layering …. that you are getting to.
Best, David
Sorry to keep bugging you ….
In the section, “2 – Bleaching in second wash bath” you wrote: “This example piece … shows the difference between a 10m water wash, a 30s acid bath followed by 10 10-minute water washes, and a 20-minute water wash. You can see from the image below that the extended second wash, of 20 minutes, has already caused some bleaching.”
Did you mean a 30 second acid bath followed by 10 (ten), 10-minute washes – for a total wash time of 100 minutes? Or did you mean a 30-second acid bath followed by a 10-minute water wash?
Best, David
Hi David F,
To answer your additional questions about dilutions, naming the solutions, and bleaching.
20/8 solution is 20g/100ml of A, 8g/100ml of B.
5/2 solution is 5g/100ml of A, 2g/100ml of B – which is indeed standard 20/8 solution diluted 1 part solution:3 parts water.
10/2 solution is 10g/100ml of A, 2g/100ml of B, which can be made by first diluting my standard A solution with an equal amount of water (1 part solution: 1 part water), then diluting my standard B solution with 1 part solution:3 parts water, and finally, mixing those diluted A and B solutions together in a 1:1 ratio.
5/8 solution is 5g/100ml of A, 8g/100ml of B – so I dilute the A solution 1:3 with water, then mix that diluted solution with an equal volume of my standard B solution.
To vary the ratio of the chemicals as well as the strength you have to dilute them individually BEFORE mixing the two together. I hope that makes more sense! I sometimes forget that I have more chemistry in my background than the average photographer.
So yes, I diluted the solutions, altered the ratio of the two chemicals in two instances, and had to slightly bleach one of those to get a light enough base layer for the text transparency to show up.
BTW I expose the text transparency in a UV unit because the paper is dried before exposing. This gives me a much shorter exposure time, and the UV unit gives me better control over the exposure, but this step can absolutely be done outside!
I encourage you to try some simple dilutions (and keep good notes). Also, if you can mix your own chemistry up from dry it becomes easier to see what the dilution numbers mean.
Hi David F,
Thank you for your questions, let me try and go through these in order:
Q. Is it important that the chemigrph be exposed outside (and not inside with a UV lamp)? Or are you saying you just used sunlight in this instance – but that’s not required for this process?
A: No, it’s not vital to expose outdoors, but the exposure length is very long in my UV unit (because the paper is so wet) and I find it much faster to use sunshine for chemigraphs when I can.
Q. You mentioned a “standard 20/8 solution”. I’m not familiar with this designation or “short hand” (and perhaps i need to reread parts 1-4?). My standard mix is half each of: 40 g Potassium Ferricyanide in 400 ml water (solution A); and 100 g Ferric Ammonium Citrate in 400 ml water (for B). So I might think of this as my 40/100 or 20/50 standard solution? Are you saying you use a differnt ratio of A to B for your standard solution? Or …?
A: The pre-mixed bottles from Bostick & Sullivan that I can find at the art supply store or online are mixed as 20g/100ml of Ferric Ammonium Citrate (A), and 8g/100ml of Potassium Ferricyanide (B), otherwise known as 20/8.
So your solutions of 100g/400ml of Ferric Ammonium Citrate (A), and 40g/400ml of Potassium Ferricyanide (B) would be 25/10 when converted to grams/100ml. Does that help?
I’m going to answer the other question separately to reduce confusion.
More questions: you said: “It is possible to partially bleach that first exposure in weak sodium carbonate if it comes out too dark. The dilutions I tested were 5/2 (20/8 diluted 1:3 with water), 10/2, and 5/8.”
I get bleaching the chemigraph layer to lighten it so the image layer can stand out. But I am not sure what you are saying about these dilutions? Are you saying you diluted your stock A/B solution for the chemigrahh layer (and you also slightly bleached it)?
And if so, I don’t understand your naming convention for these dilutions? I understand diluting 1 part of your standard A/B with 3 parts water, but i don’t understand how a standard 20/80 solution (or in my case 20/50) translates into referring to these as 5/2, 10/2 and 5/8?
Again, thanks.
Thanks again for this informative series. A few questions: You wrote: “… I first exposed a chemigraph outside. After the print was fully washed and dried, I recoated the paper with standard 20/8 solution and exposed the second time with transparencies in my UV unit.”
Q. Is it important that the chemigrph be exposed outside (and not inside with a UV lamp)? Or are you saying you just used sunlight in this instance – but that’s not required for this process?
Q. You mentioned a “standard 20/8 solution”. I’m not familiar with this designation or “short hand” (and perhaps i need to reread parts 1-4?). My standard mix is half each of: 40 g Potassium Ferricyanide in 400 ml water (solution A); and 100 g Ferric Ammonium Citrate in 400 ml water (for B).
So I might think of this as my 40/100 or 20/50 standard solution? Are you saying you use a differnt ratio of A to B for your standard solution? Or …?