Cyanotypes V: Tweaking the Curve

December 20, 2021  •  Leave a Comment

I have fell down this cyanotype rabbit hole really deep and thus started numbering this series for an easier reference. This is the fifth installment and I already have a few more in the works. If you'd like to catch up on the previous episodes, I've provided links at the bottom of this post.

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So what was the next thing to learn? As you can see in the first photograph below, I have been getting very dark mid-tones resulting in a compressed tone curve with mostly dark tones and then usually blown highlights.

Milotice Chateaux Cyanotype - Original Tone CurveMilotice Chateaux CyanotypeOriginal Tone Curve

Milotice Chateaux Cyanotype - Original Tone Curve, An Original Hand-Made 5" x 7" Cyanotype
Chemically printed on a hand-coated Shizen Design textured surface cold pressed recycled watercolor paper

To fight back, I had tried to select mostly bright photographs that seemed to work much better, as in the Helfštýn print below. However, I did not want to be at the mercy of the process and wanted to be able to print any of my black and white photographs.

Helfštýn Castle Palace Gate - Original Tone Curve with a Brighter PrintHelfštýn Castle Palace GateOriginal Tone Curve with a Brighter Print
Helfštýn Castle Palace Gate - Original Tone Curve with a Brighter Print, An Original Hand-Made 5" x 7" Cyanotype
Chemically printed on a hand-coated Shizen Design textured surface cold pressed recycled watercolor paper

Since I am printing inkjet negatives for my Cyanotypes, I decided to address the problem by adjusting the tone curve of the original print. Aparently, what looked great on screen or in an inkjet print did not look its best as a Cyanotype. I fired up Gimp and created the below swatch of tones. I started at an RGB value of 0 for all colors and added squares of increasing brightness all the way through 250 for each color. At the end, I had room left for a few more squares so I also added 215, 225, 235, and 245 just in case the fine details mattered but that did not end up being the case. Then I printed my negative as usual and created a Cyanotype.

A Cyanotype Test Tone Swatch - Original Tone CurveA Cyanotype Test Tone SwatchOriginal Tone Curve

A Cyanotype Test Tone Swatch - Original Tone Curve
Chemically printed on a hand-coated Shizen Design textured surface cold pressed recycled watercolor paper

As you can see above, the results confirmed what I saw in my prints. There was pretty much no tonal difference between 0 and 90, then a nice range between 100 and 200, and then cut, max brightness reached. I did a bit of Internet searching and found that some take this to an exact science where the print can be scanned and run through software to generate as accurate of a curve as possible. I chose to wing it and leave more to the chance. I actually liked the deep tones of my prints and did not want to open the shadows to a point of the prints looking like a regular black and white print, just in blue.

Looking at the swatch I decided that my current value of 50 really should be at 100 and pushed the curve up accordingly. I also lowered the peak from 255 to 230. I don't claim these adjustments make it perfect neither do I know whether I am settled on these values with finality but it was certainly a step in the right direction, at least to my taste. Take a look below.

A Cyanotype Test Tone Swatch - Optimized Tone CurveA Cyanotype Test Tone SwatchOptimized Tone Curve

A Cyanotype Test Tone Swatch - Optimized Tone Curve
Chemically printed on a hand-coated Shizen Design textured surface cold pressed recycled watercolor paper

I liked I got a much nicer gradation even if there was still a bit of compression left in the darkest and brightest tones. So what was left? It had to be tested, right? I made the same tone curve adjustments to the original Milotice photograph and reprinted a new negative and a Cyanotype. You can see the result below.

Milotice Chateaux Cyanotype - Optimized Tone CurveMilotice Chateaux CyanotypeOptimized Tone Curve

Milotice Chateaux Cyanotype - Optimized Tone Curve, An Original Hand-Made 5" x 7" Cyanotype
Chemically printed on a hand-coated Shizen Design textured surface cold pressed recycled watercolor paper

And to close things off for today's post? Let's put the two side by side.

Milotice Chateaux Cyanotype - Original Tone CurveMilotice Chateaux CyanotypeOriginal Tone Curve Milotice Chateaux Cyanotype - Optimized Tone CurveMilotice Chateaux CyanotypeOptimized Tone Curve

If you decide to try Cyanotypes I hope this quick overview will help you out. If you have any questions about this process, don't hesitate to ask, I'd be happy to help. And if you like one of mine and decide to buy it, that would be great too and I'd enjoy shipping it your way very mcuh.

Enjoy The Beauty That Surrounds You! #etbtsy

Previous posts in the Cyanotypes series: 1. First Cyanotype - 2. More Cyanotypes - 3. Highlands Cyanotypes - 4. How do Cyanotypes Happen? - 5. Cyanotypes V: Tweaking the Curve

If you like cyanotypes you can explore the Cyanotypes Photo Gallery dedicated to my growing collection of them. Would you like to browse through traditional darkroom wet prints? Visit my Darkroom Photo Gallery and enjoy! Do not hesitate to contact me whether you would like to learn more or would like to purchase one of my prints.

Using my links to do your shopping keeps me sharing more photographs and writing the stories behind them (commission earned) and costs you nothing. You can also use the Amazon search box in bottom left for anything at all. I truly appreciate each purchase, no matter how large, no matter how small. Thank you!

Steel sculpture of a bison in front of an old double-decker bus and a grain elevator for the background. An original hand-made 5" x 7" cyanotype print from Buffalo, NY.Buffalo, NYCyanotype Edward M Cotter's solo at Buffalo's Canalside. An original hand-made 5" x 7" cyanotype print from Buffalo, NY.Edward M Cotter's Solo ShowCyanotype An old house by a train station. An original hand-made 5" x 7" cyanotype print from Eureka Springs, Arkansas.Old HouseCyanotype


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