Cyanotype Toning formulas
I’ve been working with cyanotype toning baths awhile now, and while I haven’t figured out which ones work best or which one(s) I prefer, I have some basic approaches I’ve locked down.
Bleaching/redevelopment:
For the most part, I prefer the effects you get when you first bleach back the print, either for a short while (just until the shadows go from blue to purple, 30-60s) or for a long time (until the image fades to a pale brown/yellow and only the deepest shadows remain a faint gray/blue). Toning without bleaching is very slow and as a result the paper/highlights stain more than I’d like.
Light bleaching results in much of the blue remaining in place, so that the toning happens over it. Heavy bleaching replaces the blue with another color. It can be disconcerting to watch the image fade away, but it’s equally thrilling to watch it come back—often very quickly—once it hits the toning bath.
So far I’ve only tested sodium carbonate bleaching, I still need to test whether ammonia or other alkali work better/differently.
Bleach concentrations:
| Type | Reagent | g / liter | timing |
|---|---|---|---|
| Short | Na2CO3 | 1 | 30-60s |
| Long | Na2CO3 | 4 | 5-7m |
Toning baths:
| Toner | tbs / liter | color | staining | notes |
|---|---|---|---|---|
| Instant Coffee (Nescafe) | 8 | navy/slate/gray | none | Dissolved in 180F water, remaining water added to cool |
| Green Tea (sencha) | 4 | blue/violet | mild | Steeped in 180F water for 10m, remaining water added to cool |
| Black Tea (English breakfast) | 4 | Dark blue/violet | heavy | Steeped in 180F water for 10m, remaining water added to cool |
| Wine Tannin (home-brew grade) | 2 | eggplant black | mild | Dissolved in 180F water, aged overnight |
Some preliminary color notes:
- Instant coffee gives muted tones. If bleaching is mild, the coffee tames the blues to a deeper navy. Longer bleaching gives slate blue tones. However, if you bleach back the image to yellow, it never fully recovers, and you end up with a faint gray/brown image. Coffee doesn’t stain the paper much at all, which is nice.
- Green tea can vary widely. With mild bleaching, it give a split tone, turning the shadows purple black and the highlights rose gray. More bleaching can make the final image eggplant black. Green tea doesn’t stain much at all.
- Black tea seems similar to green so far, though it stains the paper quite brown, which does make the end result look quite different.
- Wine tannin is the quickest way to a pure eggplant black. Unlike tea, it’s more pure in color. And it doesn’t stain the paper much either.
Method:
Timings vary, but my current MO (working with prints that have been dried and aged at least overnight) is:
- Prewet print 5m
- Bleach (short/long)
- 3x wash
- Tone until desired color achieved (10 to 60m)
- Wash until water runs clear
Another method I have tested is this one (found here):
- Prewet 24h aged print 5m
- Tone until the highlights go tan (5-10m)
- 3x wash
- Bleach until shadows go purple (30-60 seconds)
- 3x wash
- Soak in weak hydrogen peroxide solution for 30 seconds
- Return to toner until shadows go black (~15 minutes)
- Wash until water runs clear
Some possibly useful web links about cyanotype toning:
https://mpaulphotography.wordpress.com/2011/04/01/cyanotype-toning-the-basics/
https://mpaulphotography.wordpress.com/2010/10/28/green-tea-the-cyanotype-super-toner/
https://mpaulphotography.wordpress.com/2011/03/04/cyanotype-toning-wine-tannin/
https://mpaulphotography.wordpress.com/2010/07/16/coffee-is-actually-useful/
http://grahamp.dotinthelandscape.org/cyanotype.html
http://artandwater.blogspot.com/2012/08/12-different-cyanotype-tones-compared.html
http://www.co-mag.net/2007/ammonia-cyanotype-toning/
http://berk-edu.com/HYB_subsite/PDF_hyb/ToningWithTea.pdf