Ammonia / tri-ammonium citrate for Simple Cyanotype

PGum · Aug 3, 2025

Good to know those work so well. I wonder if the SC formula is more sensitive to shorter wavelengths than the traditional one? However I wouldn’t expect such a massive speed difference based on that alone!

koraks · Aug 4, 2025

PGum said:
I wonder if the SC formula is more sensitive to shorter wavelengths than the traditional one?

I don't expect so. It's ultimately the same sensitizer (FAC) with the same spectral absorption as in regular cyanotype. The difference is likely just in electrochemical efficiency.

fgorga · Aug 4, 2025

koraks said:
I don't expect so. It's ultimately the same sensitizer (FAC) with the same spectral absorption as in regular cyanotype. The difference is likely just in electrochemical efficiency.

Agreed!

nmp · Aug 4, 2025

koraks said:
I don't expect so. It's ultimately the same sensitizer (FAC) with the same spectral absorption as in regular cyanotype. The difference is likely just in electrochemical efficiency.

electrochemical or photochemical?

:Niranjan.

koraks · Aug 4, 2025

nmp said:
electrochemical or photochemical?

I'd say electrochemical, unless I'm overlooking an obvious reason why photon capture would be more efficient in either case.

PGum · Aug 4, 2025

In this 2023 thread link

zuluz did a side by side test of simple vs classic. Using fluorescent tubes, they found that simple was one third as fast. Using 365 nm LEDS, they were about equal. Of course I can’t speak to the quality of the test but a factor of 3 speed difference suggests that perhaps there is a wavelength dependancy. Beyond the variability of coating thickness, maybe sensitizer aging has something to do with it, but again, a factor of 3 makes me wonder!

nmp · Aug 4, 2025

koraks said:
I'd say electrochemical, unless I'm overlooking an obvious reason why photon capture would be more efficient in either case.

May be it is semantics or I am just confused, but what electro-chemical reaction is occurring here?

:Niranjan.

nmp · Aug 4, 2025

PGum said:
In this 2023 thread link

zulus did a side by side test of simple vs classic. Using fluorescent tubes, they found that simple was one third as fast. Using 365 nm LEDS, they were about equal. Of course I can’t speak to the quality of the test but a factor of 3 speed difference suggests that perhaps there is a wavelength dependancy. Beyond the variability of coating thickness, maybe sensitizer aging has something to do with it, but again, a factor of 3 makes me wonder!

Wonder if Simple FAC would also do the same in hypo-cuprotype which suffers from a too long of a exposure requirement. Something to try.

:Niranjan

nmp · Aug 4, 2025

PGum said:
In this 2023 thread link

zulus did a side by side test of simple vs classic. Using fluorescent tubes, they found that simple was one third as fast. Using 365 nm LEDS, they were about equal. Of course I can’t speak to the quality of the test but a factor of 3 speed difference suggests that perhaps there is a wavelength dependancy. Beyond the variability of coating thickness, maybe sensitizer aging has something to do with it, but again, a factor of 3 makes me wonder!

Mike Ware says it is faster, but I couldn't find side by side comparison -

"Exposure depends on the chosen scale of contrast but is significantly
shorter than that needed for the Classic cyanotype process - probably
about 5 to 10 minutes under an average 365 nm UVA light source (e.g. a
facial tanning unit) should suffice."

p239, Cyanomicon.

:Niranjan.

Raghu Kuvempunagar · Aug 4, 2025

nmp said:
Wonder if Simple FAC would also do the same in hypo-cuprotype which suffers from a too long of a exposure requirement. Something to try.

Simple contains Nitrate (oxidiser) which might not go well with Thiosulphate (reducing agent).

Catalysis of a sodium thiosulfate and iron(III) nitrate reaction

Investigate the effect of transition metal catalysts on the reaction between iron(III) nitrate and sodium thiosulfate. Includes kit list and safety instructions.

edu.rsc.org

koraks · Aug 5, 2025

nmp said:
May be it is semantics or I am just confused, but what electro-chemical reaction is occurring here?

:Niranjan.

It's semantics indeed, but I'd consider all redox chemistry, which is central here, to be electrochemical in essence. Yes, you could argue that all chemistry is electrochemistry, and you end up realizing that there's actually no such thing as chemistry per se and it's all physics if you get down to the details...and maybe if we go there, we might conclude that all that remains is mathematics, or perhaps if we break that down, it's just philosophy. Anyway, I did not mean electrochemical in the sense of chemical batteries etc., although evidently the chemistry as such is related. It's just that there's no external circuit, although the presence of an electrolyte is essential in parts of the process.

MattKing · Aug 5, 2025

koraks said:
Yes, you could argue that all chemistry is electrochemistry, and you end up realizing that there's actually no such thing as chemistry per se and it's all physics if you get down to the details...and maybe if we go there, we might conclude that all that remains is mathematics, or perhaps if we break that down, it's just philosophy.

Careful - we might have to move this post to the Ethics and Philosophy sub-forum.
Oh, and where would alchemy fit in there ?

koraks · Aug 5, 2025

MattKing said:
Oh, and where would alchemy fit in there

That's the umbrella term if we throw cooking and shady practices with goats around midnight into the mix.

Ammonia / tri-ammonium citrate for Simple Cyanotype

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Ammonia / tri-ammonium citrate for Simple Cyanotype

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