Nail Your Base Exposure Time for Cyanotype

To ensure your cyanotypes are as dark as possible, you need to determine your base exposure time.
Accompanying blog post:
jonahcalinawan.com/journal/na...

[@shanededman]

Wonderful refresher, thanks a bunch Jonah! That UV box is incredible ✨

[@blindpilot9403]

Great method. Thank you for taking the time to do this. A quick reminder about the " oxidation effect " on cyanotype . We all know the Cyanotype gets significantly darker after fully oxidate either naturally drying in air or the quick solutions.

[@amitbhandare4]

Beautifully explained..👍👍

[@studiojege287]

Good info, thanks for the video!

[@matejababnik9853]

Thank you alot 📘 cheers!

[@ginawhite1242]

Nice video - very clear and concise. Much appreciated.

[@landedjesus6805]

whats the info for uv fluorescent light for cyanotype? the ones you are using,looks really nice.

[@pageturner6428]

Could you please share what the heat press box is? What brand?

[@MehriJamshidi]

Do you use ferric ammonium citrate green?

[@connievilla7514]

Thanks for the video, great way to figure out the right exposure. Can you share where you got your UV light box? Thanks.

[@olafwDE]

As this applies to many photographical print processes, it's great to see it coming to the cyanotype world, where a lot of trial and error prevails. Thank you for sharing this. Will there be any follow-up videos?

[@jackhalfordpodcast]

similar to what I do to figure out exposure times for my screen printing.

[@PaulSafford]

Interesting

[@VBlueMcintosh]

Hi! Can I ask what bulbs you are using for your light box please?

[@aeromodeller1]

Photographic exposure is logarithmic. Your exposure times can be 1:00, 1:25, 2:00, 2:50, 4:00, 5:39, 8:00, 11:19, 16:00, 22:38, 32:00. Notice the similarity to the F/ stop numbers. Each step is square root of two longer than the previous one.

[@plateoshrimp9685]

If you want each step to represent a stop of light you’d need to double the time for each step. Matching the time to f numbers will not work. The f number is the focal length divided by the diameter of the aperture. Each f number (for a full stop, like 5.6 to 8) represents an aperture with double the area. The key relationship is that a “stop of light” means twice as much light. Two light bulbs vs four, 10 mm2 vs 20 mm2, or 5 seconds vs 10 seconds. Of course doubling the time relies on the fact that you’re not dealing with reciprocity failure, which for cyanotype, I think you probably are, so really just going with a linear scale is probably as good as anything.

[@aeromodeller1]

@@plateoshrimp9685 Going in steps of 1/2 stop gives you a finer gradation. If you are trying to pick the exposure time that gives the best print, you want fine gradations. By using half stops, you are linear on the density. Going linear on the exposure time gives and uneven spacing on density which does not allow as close a read on the quality of the image.

[@carollelivelt8625]

Does it damage the print to expose it longer than the base time?

[@olafwDE]

Additional exposure won't add any benefit to the result. Maximum density is maximum density. Think of it as the first step in a row of calibration techniques. Once you know your base exposure time, it's much easier to reproduce results, to prepare negatives' contrast for the desired print results beforehand etc.. Base exposure time helps you keeping all possible detail in the highlights as this would become dull and duller with any added exposure (less over-all contrast). To accomplish this level of calibration it's advisable to use controllable, artificial light sources, since sunny daylight is subject to change (think of clouds passing by, daytime etc.).