And what would be the times for cyanotype and vandyke? Approximately, just to put the numbers into perspective.
A New Cuprotype?
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Not sure...
For cyanotype (which I don't do often) my exposure times with only four bars installed was 8-10 min. Thus with eight bars, I would guess 4-5 min, but I have not made cyanotypes since adding the second set of bars.
I have not done Van Dyke except in a workshop using someone else's set up. Thus no direct experience with this light source. A quick search on the web suggests that exposure times for Van Dyke range from about the same as, to maybe twice as fast as cyanotype.
Van Dyke is typically far faster than classic cyanotype; about 1.5 stops if memory serves. New Cyanotype however is faster than Classic. Salted paper tends to be a little slower than classic cyanotype by 0.5 to 1 stops. There are of course variations due to different individual approaches and process parameters.
I benchmarked a couple of light sources and it looks like for my materials 30-40min exposure is not easy to achieve. I had to push 100wats of 395nm leds to an area of just 18x24cm. I had FAC and hypo that I prepared in summer. Cooper sulfate solution was fresh. This mixture required longer exposure than before (I measured it with old light source so I can compare). But most importantly darkest parts of the negative got exposed quite noticeably even with half the time. Highlight staining under a piece of cardboard is pretty mild. I guess I have to stop. At least until I miracuolosly come across ink-ohp combo that blocks UV well enough.
As a side question, as I already have some hype do you guys think it is worth getting some silver nitrate for Van Dyke? I read there also issues with Dmax and that people double-coat (which doesn't seem easy to me).
Edit: And also my negatives seem to be not dense enough. They are enough for cyanotypes, but at double-triple time staining of highlights becomes visible.
As a side question, as I already have some hype do you guys think it is worth getting some silver nitrate for Van Dyke? I read there also issues with Dmax and that people double-coat (which doesn't seem easy to me).
Edit: And also my negatives seem to be not dense enough. They are enough for cyanotypes, but at double-triple time staining of highlights becomes visible.
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I would be careful with hypo solution storage for long periods of time as it tends to oxidize producing sulfur (which would potentially cause staining) - more or less depending on conditions. To be on the safe side, I normally prepare just the amount I would need for a couple of weeks worth of experiments which is usually no more than 25 ml at a time. It's fairly easy and cheap to prepare so no need to make a big batch ahead of time. The other two ingredients can stay good indefinitely (save for occasional mold in FAC.)
:Niranjan..
Happy New Year, and just a quick thought that perhaps would add to this process.
While I was watching a YouTube video of NileRed-Blue, I heard him say about cleaning his Copper-sulfate waste with Vitamin C to reduce it.
I have not tried to incorporate it in some test, but any of you perhaps have had the same thought?
Either in the initial coating or as part of the development thereafter?
Best regards
Jan.
While I was watching a YouTube video of NileRed-Blue, I heard him say about cleaning his Copper-sulfate waste with Vitamin C to reduce it.
I have not tried to incorporate it in some test, but any of you perhaps have had the same thought?
Either in the initial coating or as part of the development thereafter?
Best regards
Jan.
Hmmm...
How about a link to the video so we can see exactly what you are asking about?
What you suggest does not make much sense chemically. Copper(II) is not particularly toxic but neither is Copper(I), so making this conversion for disposal doesn't seem worthwhile. Furthermore, copper(II) is the prevalent form of copper in the environment.
That said, what exactly are you wanting/expecting to achieve by adding vitamin C to the cuprotype process?
I don't think that adding vitamin C at any stage will improve cuprotypes. Vitamin C will reduce both iron(III) and copper(II) in a reaction that is independent of light. Thus, I would guess that this will lead to a chemical fogging and, at the very least, trouble getting good highlights.
Just noticed this as a side comment in above video link.
Just to clarify, I am just looking to have some further means to tweak the process or enhance it. Not to do any clean-up of chemical waste which is minimal when making cuprotypes.
I guess remains to experiment a bit and see if there is any use for it.
Asking Bing-Chat it seems to give some interesting options:
-- Answer
If you add vitamin C (ascorbic acid) to a solution of copper sulfate, you will get a redox reaction that produces copper (I) chloride and dehydroascorbic acid. The equation for this reaction is:
2CuSO4(aq)+4NaCl(aq)+C6H8O6(aq)→2CuCl(s)+2Na2SO4(aq)+2HCl(aq)+C6H6O6(aq)
Copper (I) chloride is a white solid that may turn green in moist air due to oxidation. Dehydroascorbic acid is a yellowish liquid that can be further oxidized to oxalic acid.
--- Answer
Yes, the reaction between vitamin C and copper sulfate would be influenced by UV light. As I explained before, UV light can reduce copper (II) to copper (I), which is the same effect that vitamin C has. Therefore, UV light would speed up the reaction and increase the amount of copper (I) chloride and dehydroascorbic acid produced. This would also affect the color of the solution, as copper (I) chloride is white and copper (II) sulfate is blue. The solution would become lighter in color as more copper (II) is reduced to copper (I). This is why the cuprotype process uses UV light to create images on paper coated with copper sulfate1. UV light also affects the stability of vitamin C, as it can degrade it to other compounds2. This means that the concentration of vitamin C in the solution would decrease over time when exposed to UV light. Therefore, if you want to use this reaction in an alternative photography process, you should control the amount and duration of UV light exposure to achieve the desired results.
"tweak the process or enhance it" is a pretty vague goal. Did you have a specific photographic goal in mind?
Yes, please, do the experiment and report the result here.
My hypothesis is that you will get a fogged cuprotype. How bad the fogging will be is anyone's guess. (And will depend on the exact conditions you use.)
The options might seem to be interesting but they are not when scrutinized closely.
This is indeed true and is what I stated in the last paragraph of my previous response. Adding ascorbic acid to Cu(II) will produce Cu(I) in an light independent reaction. This is likely to cause fogging of a cuprotype.
It is probably worth reviewing the chemistry of cuprotype...
The light-sensitive reaction is the reduction of Fe(III) to Fe(II). The resulting Fe(II) then reduces Cu(II) to Cu(I) which goes on to form the pigment.
Thus any reaction that forms either Fe(II) or Cu(I) in a manner independent of light will result in the formation of pigment on the paper in places not exposed to light under the negative.
True. Cu(I) is not particularly stable in air when water is present. Under these conditions (i.e. the presence of water and oxygen) Cu(I) is oxidized to Cu(II).
However, the reaction shown above is not particularly relevant to cuprotype as there is no chloride present.
The important anion in the current iteration of cuprotype is thiosulfate. Copper(I) thiosulfate is very insoluble in water and thus stays where it is formed in the paper when one washes out the iron and then adds potassium ferricyanide allowing the final image to be formed.
Other salts of Cu(I) may well work for cuprotype, if they are insoluble enough in water. Jim Patterson suggested that bromide would work for cuprotype and several of us were able to make "bromo cuprotypes". However, copper(I) chloride is much more water soluble than either the bromide or the thiosulfate and thus is not likely to give a satisfactory cuprotype.
This is utter nonsense. Dehydroascorbic acid is a white solid. Additionally, the conditions under which dehydroascorbate can be reduced oxidized to oxalate are very, very far from the conditions we have in cuprotype. Thus this reaction is irrelevant for our purposes.
Again, utter nonsense. Who is the "I" in the second sentence? Bits and pieces of this paragraph are true in isolation but have they no real relevance to cuprotype.
The photoreduction of Cu(II) to Cu(I) requires the presence of other compounds that act to catalyze this reaction. None of these catalysts are present in cuprotype. Thus this is completely irrelevant to cuprotype.
Additionally, the above response completely ignores the role of iron in cuprotype.
Please remember, artificial intelligence has a close cousin named "automated stupidity".
I like it when it says - as I explained before....
It would be nice if it were true. We wouldn't need any FAC.
Quite some time ago I had this idea to make a copper based image - a while before our foray into thio-cuprotypes. I never followed thru to completion as to its viability (like most of my ideas,) but it involved reduction with Vitamin C.
The process was envisioned thusly:
1. First expose a blanket coating of ferric oxalate thru the negative.
2. Develop with water which removes Fe(3) leaving bright yellow Fe(2) oxalate on the paper.
3. Then treat it with copper sulfate for form light blue image of copper oxalate which is insoluble while ferrous sulfate is soluble which can be washed out.
4. Treat with alkali to make Cu(OH)2 which is darker blue.
5. Reduce Cu(OH)2 to copper with Vitamin C
6. Then somehow make Cu2S or CuO which are both black giving a black and white image or whatever darker color it decides to give.
I think, IIRC, I was able to do 1-4 on paper, 1-5 in test tube. Never did the step 5. Except once while filtering the Cu(OH)2, it spontaneously became black which I was not able to reproduce but most likely Cu(OH)2 dehydrated to CuO, which apparently happens in wet state. If this reaction were to happen on paper then Step 5 can be avoided and go straight to 6 - unless making a metallic copper image was the goal.
:Niranjan.
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I know but it is great in pulling info from all over the web and it is pretty well informed about the cuprotype process.Please remember, artificial intelligence has a close cousin named "automated stupidity".
Thank you for the detailed explanations, I agree with you that at most places in the process it will probably result in a contrast less brown image.
This sounds like an interesting route, worth to give it a try. Yes the goal would be to have more contrast and better whites, perhaps even something black like a silver print. The other thing I have somehow in mind is to get a positive in the process rather then negative.
thank you for sharing that process setup.
The copper-plating effect I have reached somehow (at random) in below linked example. The image shows shiny leaves of the plant, the darker parts are not reflective.
I think it was due to the methanol / Curcuma mixture.
When talking to Gen.AI I try to be polite, never know what it will remember in a few years from now
This sounds like an interesting route, worth to give it a try. Yes the goal would be to have more contrast and better whites, perhaps even something black like a silver print. The other thing I have somehow in mind is to get a positive in the process rather then negative.
thank you for sharing that process setup.
The copper-plating effect I have reached somehow (at random) in below linked example. The image shows shiny leaves of the plant, the darker parts are not reflective.
I think it was due to the methanol / Curcuma mixture.
When talking to Gen.AI I try to be polite, never know what it will remember in a few years from now
Once you get a metallic copper image, it can also be turned to copper sulfude using liver of sulfur as they do in making patina - and call it patinatype.
Niranjan.
Seems like a copper analogue of a 'halochrome' toner, very interesting. Indubitably so if the process is repeatable... and not de-railed by a hallucinating AI 
Maybe try applying a DC voltage across the print next time. Electro-patinatype has a nice ring to it.
Great thread BTW. I suggest anyone reading this to start at the beginning if they haven't yet and give this process a try.
Maybe try applying a DC voltage across the print next time. Electro-patinatype has a nice ring to it.
Great thread BTW. I suggest anyone reading this to start at the beginning if they haven't yet and give this process a try.
Seems like a copper analogue of a 'halochrome' toner, very interesting. Indubitably so if the process is repeatable... and not de-railed by a hallucinating AI
Maybe try applying a DC voltage across the print next time. Electro-patinatype has a nice ring to it.
Great thread BTW. I suggest anyone reading this to start at the beginning if they haven't yet and give this process a try.
Hi, Bronson:
Always wondered how this halo-chrome worked. Per their explanation, it is supposed make the grains fuse together to convert colloidal silver into sold silver. But how, any ideas?
:Niranjan.
I don't have any particular insights into the chemistry in either case, but it's almost certainly a result of physical development altering the crystal structure of the reduced metals. A sort of ad-hoc Tollen's reagent in the case of halochrome. There may be a similar reaction that can happen with copper but... it is a mystery.
Interesting....I wonder if anyone tried to use Tollen's reagent to make daguerreotype plates.
:Niranjan
What are your concentrations of chemacals and coating process? I am looking at hypo-cuprotypes but somehow coating does not work for met.
You might want to take a look at this... https://www.alternativephotography.com/cuprotype-process/
Full disclosure... I wrote the above cited article.
That's what's I am following, yes. I use your concentrations with various papers. I observe inconsistency in depth of brown between coats and I can't figure out the soure. I tried single/double coats, different papers, different tween concentrations, different dilutions of chemicals etc. This thing has been puzzling me for months. I figured out that with Cu-FeCn toner and then partial iron toning I can potentially achieve very dark browns, way darker than Van Dykes. But I can't reproduce it consistently.
Oh! I was not planning to go down this particular rabbit hole but that's got me more curious. I might have to give this a try too!
All else being equal, I would speculate that the sulfur chemistry involved in the initial image making step is the wildcard in this process. AFAIK this is the only process that utilizes a sulfur compound in the sensitizer (sulfur sensitized b&w emulsions notwithstanding). The exact concentration and variety of thiosulfate species/complexes could vary wildly based on precise solution concentrations, temperature, age, addition rate, contaminants, exposure to light, etc.
Are the variations you're experiencing are 'baked' into the initial exposure? Or are the subsequent toning steps also subject to variation?
I think it is the coating-exposure step. After exposed sheet comes out it is either lighter or darker mustard. Then it is mostly consistent. Darker yellow images tone to darker brown and lighter to more washed out brown. At this stage I don't even have to do the first toning step to tell how it will turn out, it is already clear from the freshly exposed image.
I was thinking of buying new batch of copper sulphate and sodium thyosulphate. Not sure if it makes sense from chemical standpoint but it's cheap to try.
I have test strips. Lower left is sucessufful coating, after cu-kfecn toner. Above is it but partly toned with iron toner (nmp's recipe). Lower right is less sucessuful batch, but when toned with iron toner it is still pretty dark (upper right image). Middle is VDB. It is hard to judge absolute values by photo, in real life differences look more striking. VDB level is achievable not even with my best coating.
I don't like the idea of partial toning, but I think it is manageable if I tone the whole series in one batch, like we do with cyanotypes and herbsl toners. If I could achieve the lower left level of hatchet's brown consistnely I wouldn't even bother with second toning.
I also tried iron toning after simple kfecn toner with little luck. It does not wash properly of my papes staining highlights blue after iron toning. And the overall tone is sort of dirty and washed out. So I'd stick with cu-fecn and optinally iron toner after.
As I understand longevity of iron toned cuportypes is not studied, while for van-dykes we now for sure that they fade. Both options of getting brown are not perfect. I think Jim Patterson wrote somewhere that his cuprotypes look fine after 10+ years, but he probably meant those without second toning.
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Looks like you are getting fairly good Dmax's, particularly the iron-toned ones.
Regarding reproducibility, like all other alternative processes, some more than others, many factors contribute to the outcome so we try to control them as much as we could. Like humidity, temperature, concentrations, freshness of the ingredients etc which are of day-to-day variety. Even how much liquid is brushed on will make a difference. Lot of practice is needed I guess to be consistent in the brushing (or rod coating) technique. Frankly, I don't trust drop system of adding various components - I use weights. It is not as convenient but considering I have a tendency of forgetting the count halfway, it works better for me. For humidity control I always equilibrate my paper at least overnight in a saturated salt chamber kept at 78 C and keep the sensitizer components at the same temperature because my work area conditions are at the mercy of seasonal changes.
Also, regarding iron toning, what it is really doing is making cyanotype out of cuprotype (or copper toned cyanotype) so longevity presumably would be expected to be no different from a regular cyanotype.
:Niranjan.
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What exactly do you mean? I mix soulutions by volume like 1:2:3 but the solutions themselves are prepared by wieght. All relatively fresh.
The variation I get is pretty wild. Here is the same paper that I tried during the las couple of weeks. If that's the normal sensitivity of the process to humidity/temperatue/coating then it is unusable and I should give up. But maybe it something else.
I built a special exposure unit for cuprotypes that gives 15 minutes exposure and every time I intend to throw it away I think maybe I should still experiment a bit more.
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