Cyanotyping

I think I replaced it with the normal public one. You can see it on my channel

Nile Red

video gone

With respect to timing your exposure and it’s nonlinearity I propose the hypothesis that it may work similar to regular film “stops” where a stop brighter or l darker is a doubling for halving the total light energy delivered to the film. E.g. say your exposure when taking a picture was 1/60s, a stop brighter would be 1/30s and a stop darker would be 1/120s, which would be a 2^x factor, thoughts?

Ash

hmm, im not really sure.

Nile Red

Any idea what the sensitivity curve is? I have both uva and uvb for my light box. I'm guessing uva is best, but don't want to assume...

Michael Aichlmayr

Very cool!

Good thinking. It was so satisfying to see that line appear. I love when data bears out theory. But, yeah, it might have been a bit much for the video though. Lol. You mentioned that you couldn't find much information online for cyanotype kinetics. Have you thought about writing up this neat little kinetics experiment into a paper? I could see this being very welcome in a journal like J. Chem. Ed. because it's fun to perform and the data analysis is not hard. That could be a great milestone for your channel. You might also consider looking into chemical education funding from some chemistry societies like ACS (though I know you're in Canada).

There is a lot to read, and my notes now extend over a few dozen handwritten pages. Need to find the time to type them but the above is a very concise summary. Lots of information at katharinethayer.com

Silviu T

Also, good tips about the cyanotype. I might look into the gum-bichromate method in the future and your info will definitely help

Nile Red

Yeah sure, send em over to admin@nilered.ca. It sounds like you have quite the project ahead of you lol

Nile Red

I actually did something very similar! And it would definitely help dial in exposure. I just felt it was a bit too much to add to the video lol

Nile Red

Some of my notes for the gum-bichromate, many don't apply to the cyanotype. 1. need to pre-shrink the paper so it doesn't change dimensions through many washes (soak in hot water, hang to dry, soak again in cold water, wipe water off, place between paper towels, with a weight on top and dry overnight to eliminate wrinkles). 2. "sizing" of paper i.e. quenching to eliminate pores as you don't want the pigments to seep into the paper (as opposed to the cyanotype where you do want that) Traditionally done with a solution of gelatin followed by a hardener (formaldehyde, glyoxal or chromium salts+exposure to UV). Modern alternatives: acrylic gesso or PVA glue. 3. "registering" of the negatives i.e. a method for aligning them precisely for successive exposures, both for the greyscale and the full-color process (you need to build up multiple layers of gum for each color, usually 2-3 or more; multiply by 4 for the color process). 4. pigment balance: you want to use colors which when combined give you accurate rendition of original colors. Need to experiment to find appropriate amounts of pigment in each layer. Recommended pigments: for yellow - Arylide yellow PY97; magenta - quinacridone rose PV19; cyan - phthalo blue green shade PB15:3; black - lamp black. Order of layers from bottom to top: yellow-magenta-cyan-black.

Silviu T

Try a ferrous salt instead of ferric.

Silviu T

Very nice. Good timing too: I am gearing up to explore another alternative process, the gum-dichromate (or gum-bichromate as it's called by photographers on historical reasons). I've been reading a lot, as there are many more variables involved than in the cyanotype. Some of those do apply to the cyanotype process too and here are some suggestions. 1. Don't rely on the sun. I will use a UV lamp for exposures (low-pressure UV tube in a fluorescent light fixture). 2. Use high quality watercolor paper. My chosen paper is from Amazon made by Bee paper company, 100%cotton, 6x9 inches. 3. Use mirror images of the digital negatives (reversed left-right) placed with the toner side in direct contact with the photosensitive emulsion. This way you eliminate some of the fuzziness created by the thickness of the transparency and get much sharper images. Neither the sun nor a UV lamp are point sources so if the negative image is separated from the emulsion by the thickness of the transparency it will create regions of penumbra which will degrade the final image contrast. Eventually I want to make full color prints using this technique from sets of CMYK-separated negatives and multiple emulsion layers with watercolor paints. If you're interested I can send you my notes. (edit) Here's a crude depiction of the penumbra effect: <a href="https://s22.postimg.cc/xogs8f6sh/penumbra.jpg" rel="nofollow noopener" target="_blank">https://s22.postimg.cc/xogs8f6sh/penumbra.jpg</a> You can attenuate that to a great extent by flipping the transparency with the toner down, but you get a mirrored image this way (therefore the need to mirror the negative first).

Silviu T

Dude, way cool video! Your Singapore photograph was really great! I see now why your videos are so well made. Your mention of kinetics got me thinking. I decomposed a screen cap of your time series @13:12 into its HSV values using GIMP and recorded the median histogram Value value (0-1.0) of a selection at the top border for each time step as a proxy for exposure. Your initial guess was right that it is logarithmic. In fact, you're seeing nice (pseudo-)first order kinetics, with an R2 = 0.991 by my calculations. Take a look below. You should be able to use the equations to dial in your exposure. <a href="https://docs.google.com/spreadsheets/d/1cLsxONdQZitc_8aDB-ZaipLm9NRux8ogSwnz3rJWw7g/edit?usp=sharing" rel="nofollow noopener" target="_blank">https://docs.google.com/spreadsheets/d/1cLsxONdQZitc_8aDB-ZaipLm9NRux8ogSwnz3rJWw7g/edit?usp=sharing</a>

Happy to wait for this topic. I've really been enjoying it. Most of the channels I support have been slow this Summer. That's perfectly understandable.

Paul Grodt

That could be interesting!

Nile Red

I wouldnt say its really an issue. It's more just something thats part of the process.

Nile Red

awesome!

Nile Red

im glad you liked it!

Nile Red

Ok, that was awesome. I'm speechless (that's rare).

Brian Reddeman

Yaaaaaaaaaaay!!!! Ooit! Ooit!

Michael Aichlmayr

Watched this at work. I work in my orgs creative services group and my coworker's been in everything printing for 30 years. He learned some things from your video. He was impressed. I think you have a new fan! cheers

I tried green tea with iron chloride - No reaction. However coffee may do that.

Daniel Blake Shoemaker

Cool. Did not know about the Inversion issues.

Daniel Blake Shoemaker

Love it! Maybe Uranotyping sometime in the future, too?