A New Cuprotype?

[Raghu Kuvempunagar]

Emulsion
10ml dest water
2 gr FAC
1 gr Copper Sulfate
1 gr Thiosulfate

apply this to a sheet of paper, let dry.

I exposed here some flowers and the top one is the oiled paper-negative previously used for the FerroBlend. No new oil applied.
Exposure with UV 365nm flood light direct on top of the glass for 10 minutes.

Development
' Rinse very well with normal water changing the bath about 4 times.
developed from the light golden brown color with following mix.
- move the paper as little as possible ie no shaking of the tray just keep it covered with the developer. .

Jan, I noticed that you sensitiser recipe is similar to the one here, but the proportions are different. Is there a good reason to prefer one over the other in terms of speed and image characteristics? Just curious to know if you done controlled experimentation comparing one with the other.

p.s. I also noticed that you're engaged in convesation with Vincenzo in the same FB post that I shared here. That's great because you/Niranjan would be able to provide clarifications to his questions based on your experience with the process better than anyone. Let's hope the interaction throws more light about the chemical pathways of this process.

 

[Jan de Jong]

Jan, I noticed that you sensitiser recipe is similar to the one here, but the proportions are different. Is there a good reason to prefer one over the other in terms of speed and image characteristics? Just curious to know if you done controlled experimentation comparing one with the other.

p.s. I also noticed that you're engaged in convesation with Vincenzo in the same FB post that I shared here. That's great because you/Niranjan would be able to provide clarifications to his questions based on your experience with the process better than anyone. Let's hope the interaction throws more light about the chemical pathways of this process.

Interested by the pfd by Vincenzo, I wanted to do some quick tests, to see if we have a process only reacting with the paper fibers or a solid forming somehow. I wanted to make a strong solution and keep it simple for my test. I think my initial recipe was more 2gr FAC 1 gr copper sulfate and 0.5 gr Thio. So for now reason I took above. Just made sure I noted it down. For the tests I used a UV Floodlight direct on the glas, so exposure is between 7-10 minutes only then. I tried to get an idea first with some tests and the UV flashlight, but noticed the sensitivity is very low, probably 5 - 10 times less than normal cyanotype with this recipe.
Having some samples thereafter, I noticed Vincenzo mentioned that after exposure the color should be dark brown when it was a solid forming. He seemed to have found that is not the case. So for that reason I added my samples from after exposure and after wash in that post.
Then the "development" with K-Ferri + K-Ferro mix solves the problem of the clearing. The print will develop in the dark chocolate brown, the whites will be almost stay white. (same as in the 2 color example I posted in this tread earlier)

Certainly very interesting all. My basic interest is : Making a solution, which can be influenced under the action of light. So atom/ molecule A + B + light -> give solid - for image. requirement should not use dangerous chemicals.

 

[nmp]

Interested by the pfd by Vincenzo, I wanted to do some quick tests, to see if we have a process only reacting with the paper fibers or a solid forming somehow. I wanted to make a strong solution and keep it simple for my test. I think my initial recipe was more 2gr FAC 1 gr copper sulfate and 0.5 gr Thio. So for now reason I took above. Just made sure I noted it down. For the tests I used a UV Floodlight direct on the glas, so exposure is between 7-10 minutes only then. I tried to get an idea first with some tests and the UV flashlight, but noticed the sensitivity is very low, probably 5 - 10 times less than normal cyanotype with this recipe.
Having some samples thereafter, I noticed Vincenzo mentioned that after exposure the color should be dark brown when it was a solid forming. He seemed to have found that is not the case. So for that reason I added my samples from after exposure and after wash in that post.
Then the "development" with K-Ferri + K-Ferro mix solves the problem of the clearing. The print will develop in the dark chocolate brown, the whites will be almost stay white. (same as in the 2 color example I posted in this tread earlier)

Certainly very interesting all. My basic interest is : Making a solution, which can be influenced under the action of light. So atom/ molecule A + B + light -> give solid - for image. requirement should not use dangerous chemicals.

Here is a link to an interesting set of experiments regarding reaction between copper sulfate and sodium thiosulfate where the outcome is dependent on the variables such as ratio of the two, concentration and time. A solid product is obtained when the reactants are in higher concentration which does not dissolve once formed. Perhaps that might be the clue to what is going on here. My earlier conjecture was based on this article but then I couldn't find it.

:Niranjan.

 

[nmp]

Jan, I noticed that you sensitiser recipe is similar to the one here, but the proportions are different. Is there a good reason to prefer one over the other in terms of speed and image characteristics? Just curious to know if you done controlled experimentation comparing one with the other.

p.s. I also noticed that you're engaged in convesation with Vincenzo in the same FB post that I shared here. That's great because you/Niranjan would be able to provide clarifications to his questions based on your experience with the process better than anyone. Let's hope the interaction throws more light about the chemical pathways of this process.

Sorry Raghu, I don't have Facebook account. I can barely read the post without Facebook locking me out.

:Niranjan.

 

[nmp]

I noticed Vincenzo mentioned that after exposure the color should be dark brown when it was a solid forming. He seemed to have found that is not the case. So for that reason I added my samples from after exposure and after wash in that post.

Frankly, the color on paper sometimes has no bearing to the actual color of the pigment in the bulk. Depending on the size and resultant scattering, the observed color can be quite different for sub-micron particles. So the color of the print can not be used as a definitive proof of the presence or absence of a particular molecule.

:Niranjan.

 

[Jan de Jong]

Frankly, the color on paper sometimes has no bearing to the actual color of the pigment in the bulk. Depending on the size and resultant scattering, the observed color can be quite different for sub-micron particles. So the color of the print can not be used as a definitive proof of the presence or absence of a particular molecule.

:Niranjan.

The assumption in the pdf article if I take a shortcut that it was more an adhesion of chemicals rather than a solid forming, indicating that direct after exposure not a dark color of the emulsion would support that. That was the reason why I wanted to revisit it.
For that reason I posted in the Facebook as a reply the left image, showing left, Just after exposure, and then the lighter coffee colored the wet print after wash.
The second image I just took now, so few days later. That was developed with the K-Ferri - K-Ferro mix. returning the image the much darker brown. You can see the blue staining which was a result of not washing well. On another print the next day this did not happen.
Because I wanted to have some quick tests, I put the UV floodlight direct on the glasplate, under which a dried flower but still green stem of the Narcissus flower. It seems the dried flower blocks a lot of the UV. exposure was between 7-10 minutes. It is really slow and needs a lot of UV.
I guess to get deeper into the how much thio or what effect has what tests results of different concentrations would be useful. I do think a solid is formed and it has a nice color. Just it needs a lot of UV exposure.

 

[Jan de Jong]

Here is a link to an interesting set of experiments regarding reaction between copper sulfate and sodium thiosulfate where the outcome is dependent on the variables such as ratio of the two, concentration and time. A solid product is obtained when the reactants are in higher concentration which does not dissolve once formed. Perhaps that might be the clue to what is going on here. My earlier conjecture was based on this article but then I couldn't find it.

:Niranjan.

Thank you for the link, very interesting. it gives a nice overview of the possible things that can happen. This is similar way of working I did to come to the process in the first place. I took a set of test tubes with combinations outside in the sun while reading a book in my garden. My goal was to find a combination that would change color. The successful one was the one containing in my case then the used Hypo fix solution.

 

[Raghu Kuvempunagar]

Here is a link to an interesting set of experiments regarding reaction between copper sulfate and sodium thiosulfate where the outcome is dependent on the variables such as ratio of the two, concentration and time. A solid product is obtained when the reactants are in higher concentration which does not dissolve once formed. Perhaps that might be the clue to what is going on here. My earlier conjecture was based on this article but then I couldn't find it.

:Niranjan.

TFS Niranjan. It's very fascinating how changing the proportion can affect the aqueous mixture of Copper Sulphate and Thiosulphate and even result in the formation of an insoluble compound. I can see (and appreciate) that your formulation in OP was informed by these considerations.

Sorry Raghu, I don't have Facebook account. I can barely read the post without Facebook locking me out.

No worries.

Frankly, the color on paper sometimes has no bearing to the actual color of the pigment in the bulk. Depending on the size and resultant scattering, the observed color can be quite different for sub-micron particles. So the color of the print can not be used as a definitive proof of the presence or absence of a particular molecule.

Exactly.