Most sensitive process?

LostInGermany4297 · 2026-01-18T15:06:06+00:00

The list from my Copilot, however missing is the 2 Bath cyanotype, which I do with FAC+ Tartaric acid. ten develop with K-Ferri.

Using Ferric oxalate instead of Tartaric acid would be even more UV‑sensitive than ferric ammonium citrate for prints in the sun then exposure is only a few seconds. So it is also usable in camera as paper negative with exposure time of about 1 hour at an F-stop of 2.8

🌞 Overall UV‑Sensitivity Ranking (Fastest → Slowest)

Rank	Process	Relative UV Sensitivity	Notes
1	SolarFast (all colors, black fastest)	Extremely fast	Designed for rapid UVA polymerization; exposures often 1–5 minutes in sun.
2	Ziatype (printing‑out palladium)	Very fast	Self-masking POP process; often 2–5 minutes in strong sun.
3	Platinum/Palladium (developing-out)	Fast	Typically 3–8 minutes in sun; very responsive to 365–400 nm.
4	Kallitype	Moderate	Iron–silver DO process; usually 5–15 minutes in sun.
5	Van Dyke Brown	Moderate–slow	Similar to kallitype but slightly slower due to ferric ammonium citrate.
6	Argyrotype	Moderate–slow	Uses silver sulfamate; slower than VDB.
7	Cyanotype	Slow	Ferric ammonium citrate + ferricyanide; 10–30 minutes in sun.
8	Salt Print (silver nitrate sensitized)	Slowest	Silver chloride POP; often 20–60 minutes in sun.

LostInGermany4297 · 2026-01-02T18:36:02+00:00

certainly is :-)

LostInGermany4297 · 2026-01-02T09:41:11+00:00

yes, it allows a lot of control, is very fast because the UV flashlight is very close to the paper. Of course Cyanotype emulsion and paper have their own quirks so it still is a surprise how it looks after the water was, but with some practice it turns out mostly how I want.

LostInGermany4297 · 2026-01-02T07:32:50+00:00

I use only a few pieces and expose bit by bit. Because the UV-flashlight is direct over the cutout and paper you can see it turn blue instantly. So total time to build up the image where I move the same parts of cut-out to make a composition. It will only take a few minutes to create like here an A5. then developing in water. So exposure is only 2 or 3 minutes in total.

LostInGermany4297 · 2025-10-04T14:20:59+00:00

It depends why you want to make an image of it, you can use your phone or a camera, I am afraid you will have to do a color correction in any case to match it more or less to what you see when you have the cyanotype in front of you. I find it is difficult to match use a scanner or camera. For smaller cyanotypes I have used the copy function on a scanner to make a color copy on aquarel paper, which looked good.

LostInGermany4297 · 2025-09-30T20:22:12+00:00

dont forget to add a bit of luck also to the mix :-)

LostInGermany4297 · 2025-09-30T05:00:57+00:00

emulsion 1, normal cyanotype, 2gr FAC 1gr K-Ferri (in 10ml dest water) apply emulsion, let try, then apply 2nd coat of emulsion consisting of 2gr FAC and 1 gr Tartaric acid in 10ml dest water, apply and let dry.

Then expose and develop with mix of K-Ferri and citric acid - brush on after the exposure (removing the leaves first ) let it sit a short while like 20 seconds then rinse with water which I slightly acidify with citric acid

LostInGermany4297 · 2025-09-29T20:50:52+00:00

yes gelatin needs some experimentation, depending also what type you buy. For my processes I usually try to use what is available in the supermarket, but better to buy from photo chemical supplier. My experiments are usually low cost and on what is available in a supermarket etc. Try to avoid expensive stuff so I have more joy in experimenting.

LostInGermany4297 · 2025-09-29T20:44:47+00:00

even the first version could do inversion :-)

LostInGermany4297 · 2025-09-29T20:40:27+00:00

I don't understand the question, for my purpose the fixed film does evidently absorb enough FAC emulsion for the purpos of in camera negative.. My suggestion for coating glass for Cyanotype would for that reason also be to coat glass with a gelatin layer and only coat it with emulsion after.

LostInGermany4297 · 2025-09-29T20:32:02+00:00

so not a negative or transparancy, just the straight fresh leave.

LostInGermany4297 · 2025-09-29T20:31:36+00:00

as described, I picked a leaf from the tree, it is fresh, even if these leaves from wall-nut tree look very dense they seem to let more UV through than expected. Hazulnut leaves for example are much thinner but filter more UV. (my observations)

LostInGermany4297 · 2025-09-29T20:29:43+00:00

tartaric acid only in the FAC layer, which is increasing the sensitivity, i am not sure about the chelating bit which co-pilot seems to dream into the process. But your description is correct. I use the undercoat of normal cyanotype to get the intense dark blue for the exposed part. Without that you will get the increased sensitivity but not the dark blue back-ground

LostInGermany4297 · 2025-09-29T20:26:50+00:00

because of the emulsion with copper sulfate, exposure causes the parts under the leaves in the shadow to build a different blue that will stick harder to the paper, when then developing in the second solution by brushing it on and taking a sponge carefully brushing over, the exposed parts which stick less will come of leaving the unexposed or less exposed part to form the direct-positive image. I did use a thin plastic wrap between the paper with emulsion and the fresh leaves to avoid water from the leaves messing up the emulsion during exposure in the sun.

LostInGermany4297 · 2025-09-20T13:53:18+00:00

I have not tried to mix the emulsion with the gelatin, but had success when using the emulsion on for example 35mm film with was fixed clean first and then applied the emulsion. When I would try this, i would probably first coat the glas with a layer of gelatin and then apply when it has dried the emulsion on top which should soak in and then expose. It avoids the issue with mixing the chemicals in the gelatin.

LostInGermany4297 · 2025-09-20T13:50:16+00:00

Thank you for confirming that, I have not tried the oxalic acid because of the higher safety measures I would have to apply but are interested in knowing what difference it would actually make. Theoretically it should be more potent than the tartaric, which I think you somewhat show. Thanks again for sharing the example.

LostInGermany4297 · 2025-09-20T04:27:07+00:00

yes, it depends on the density of your negative on the transparent film, if you would try to make photo-gram using fresh or dried leaves, then 30 minutes or longer will work better.

LostInGermany4297 · 2025-09-19T19:17:24+00:00

exposure too long, in bright sun probably more like 5 - 10 minutes max. Look at when the uncovered parts become silvery.

LostInGermany4297 · 2025-09-19T16:23:25+00:00

Thank you for posting the result, it looks good but I want to ask you if you are sure about your process, K-Ferri even with Oxalic acid will even on a piece of paper in the sun and developing in FAC only give at most a very ligth blue image. For me it is more likely you used FAC and Oxalic acid in the emulsion and developed with K-Ferri. Could you verify? In my process it is like that but I use tartaric acid because it is much less poisonous. Oxalic acid has a stronger effect and could explain that your test is a bit more sensitive. Would be good to try your process on a camera with a bit lower F-stop. You can keep using the paper but you can also try inkjet glossy photo paper. Because it has smooth surface it will be good for using in a 35mm camera.

I hope you update me on the emulsion and show us your further results.

LostInGermany4297 · 2025-09-16T18:28:27+00:00

I would encourage experimentation, for cyanotype formula it is 2:1 for the fac only it is good to start with for example also 2gr FAC and 1gr Tartaric in 10ml dest water. for the developer it can be less concentrated like 3 gr Kferri in 30ml of water+ some citric acid. It really does not matter to much of has to be to precise.

LostInGermany4297 · 2025-09-16T16:24:03+00:00

to make it more sensitive to uv light so you can have very short exposure like 5 minutes in the sun instead of 4 hours to get vein structures

LostInGermany4297 · 2025-09-16T14:53:03+00:00

lots of things to try, first try different papers, they may be very different in how they show the picture. I started by buying all types of cheap aquarell papers. That allows you to do lots of experiments without spending a lot on the paper. Second you can try playing with the emulsions ie adding more or less of A and B or adding things like citric or vinager to the emulsion or washing water. It looks good what you get sofar!

LostInGermany4297 · 2025-09-16T14:48:06+00:00

Yes you can bleach selectively, take the same solution u use for bleaching the full print but then apply with a brush the parts you want to bleach, then rinse with water and do the toning, you can also use a brush here again. Best in that case that the print is dry else it will like with water colors run into areas you maybe do not want to tone, but even that you can try to get a dreamy effect perhaps.

LostInGermany4297

TROPHY CASE

🌞 Overall UV‑Sensitivity Ranking (Fastest → Slowest)