Seeking Advice on Printing Gelatin Silver Prints from Overexposed Wet Plate Collodion Negatives

Thank you very much for your comments. I really appreciate it.

I understand. If residual halides remain, they can darken when exposed to ultraviolet light. Therefore, even if the plate is varnished after being likely rehalogenated, it might be inevitable for it to eventually darken due to UV reactions.

You might already know, but in the wet plate collodion process, Copper Intensification involves rehalogenating a plate that has been fixed and washed, using a Copper bleach solution (potassium bromide + Copper sulfate), and then immersing it in a Silver nitrate solution for redevelopment. After redevelopment, the plate is not exposed to sunlight. Copper bleach and silver nitrate redevelopment are conducted in a well-lit room.

In the first place, I've been researching why such chemical reactions occur, but I don't understand despite searching online. Do you know about this mechanism?

In any case, after redevelopment, the plate is rinsed and dried without being fixed again. This seems to be a common method that many wet plate photographers use to achieve the necessary density for making POP prints like Salted paper.

Regarding my question, I was inquiring whether the image would darken if only copper bleach is used without silver nitrate redevelopment. Again, as you suggested, due to the presence of residual halide silver after copper bleach, it seems that the image will indeed darken over time due to the effects of ultraviolet light. I am planning to conduct some experiments with the plates that I recently made.

Also, in a few previous posts, Nicholas Lindan suggested using B&W stabilizer. With this method, would it be possible to fix the rehalogenated silver and avoid darkening due to ultraviolet light? I'm interested in trying out this approach as well.

Thanks again.

D_Quinn said:

You might already know, but in the wet plate collodion process, Copper Intensification involves rehalogenating a plate that has been fixed and washed, using a Copper bleach solution (potassium bromide + Copper sulfate), and then immersing it in a Silver nitrate solution for redevelopment. After redevelopment, the plate is not exposed to sunlight. Copper bleach and silver nitrate redevelopment are conducted in a well-lit room.

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Well-lit room addresses the need to seed the silver halide to get the process going. I guess I shouldn't have said "under the Sun" per se but any UV is needed for the intensification to occur.

D_Quinn said:

In the first place, I've been researching why such chemical reactions occur, but I don't understand despite searching online. Do you know about this mechanism?

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My guess is that the mechanism should be the same as that of printing-out process of salted paper where there is silver halide plus some free silver nitrate. When UV reduces silver halide into split into silver metal and gaseous halogen, the latter combines with silver nitrate for form a new silver halide which then is available under radiation to form another silver atom. And so on. This process has a multiplying effect in proportion to the concentration of the original silver halide (by correlation, the concentration of silver in the plate before bleach/re-halogenation.) This leads to the darker areas being darkened more than the lighter areas, thereby adding to the contrast and intensifying the image.

D_Quinn said:

Regarding my question, I was inquiring whether the image would darken if only copper bleach is used without silver nitrate redevelopment. Again, as you suggested, due to the presence of residual halide silver after copper bleach, it seems that the image will indeed darken over time due to the effects of ultraviolet light. I am planning to conduct some experiments with the plates that I recently made.

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In absence of any silver nitrate, the conversion to silver metal from silver halide is quite slow - it's like what you would get if you put a darkroom silver gelatin paper out in the daylight, which is what people do in making a lumen print. After many hours of exposure, you get some type of image that has different colors representing sub-micron nature of silver particles produced in this manner. It would be interesting if you get such colorful outcome with your re-halogenated plates. It's a worthwhile experiment indeed, may be not for the reason you are hoping for....

D_Quinn said:

Also, in a few previous posts, Nicholas Lindan suggested using B&W stabilizer. With this method, would it be possible to fix the rehalogenated silver and avoid darkening due to ultraviolet light? I'm interested in trying out this approach as well.

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It seems he also fixes afterwards. Primary reason for using the stabilizer, as I understand from his post, is to keep the colors of the lumen print and not lose them when fixing later, which is still needed to remove unexposed silver halide form the paper.

:Niranjan.

D_Quinn said:

Regarding my question, I was inquiring whether the image would darken if only copper bleach is used without silver nitrate redevelopment. Again, as you suggested, due to the presence of residual halide silver after copper bleach, it seems that the image will indeed darken over time due to the effects of ultraviolet light. I am planning to conduct some experiments with the plates that I recently made.

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OK, now I understand what you are trying to do (slow bulb!) You start with a negative on glass. Bleach + re-halogenation converts the black silver into white silver bromide. Then you paint it black in the back like in an ambrotype. So where the highlight would be, it will be white from the bromide and where there is no silver it will be black and everything in between, thereby giving a positive - even better than an ambrotype which has kind of stunted dynamic range, as I understand.

Is that the idea?

Unfortunately, the image will be only fleeting as the white of the silver bromide will, not stay permanent. I can't think of any other silver salt that will be white AND insensitive to UV. It would be great if there was something like that.

:Niranjan.

Yes. That was exactly what I thought it would be nice to have bright ambrotypes. It’s a shame that white silver bromide doesn’t last long though.
But I really appreciate your detailed explanations. It took me a while to digest.


Going back to what you explained.
Here is my understanding and some questions.

Intensification is carried out on the negative that has already been fixed. Based on your explanation, intensification involves the rehalogenation of silver halides that are still present on the negative, using copper sulfate. When the plate is exposed to light (UV), it triggers the formation and continuous increase of silver atoms within the silver halides. This process of silver atom formation also occurs during the rehalogenation/bleach stage, correct?

When the plate is immersed in the solution after the rehalogenation/bleach stage, it accelerates the aforementioned silver conversion process, leading to a higher concentration due to the presence of a significant amount of free silver nitrate in the solution, right?

The issue here is that once the silver atoms are formed, there is no issue. However, if silver halides remain on the plate, they can darken due to UV exposure, sooner or later. Therefore, it's better to fix to prevent this.

In the intensification process, once rehalogenation is carried out, all the silver halides on the plate need to be converted into silver atoms, otherweise, the remaining silver halides can darken due to UV exposure. Is that correct?"

Additionally, during the rehalogenation/bleach stage, what is the role of bleaching? Does it reduce the number of silver atoms that have already been converted on the plate?

I apologize for asking many questions!
If you have the time to answer, that would be greatly appreciated.
Many thanks!

D_Quinn said:

Intensification is carried out on the negative that has already been fixed. Based on your explanation, intensification involves the rehalogenation of silver halides that are still present on the negative, using copper sulfate. When the plate is exposed to light (UV), it triggers the formation and continuous increase of silver atoms within the silver halides. This process of silver atom formation also occurs during the rehalogenation/bleach stage, correct?

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Not quite.

Intensification does not happen until silver nitrate treatment. There are no silver halides present in the negative after fixing - that's what fixing does, remove undeveloped silver halides.

The job of copper sulfate is to make silver (+ve) ions out of silver metal (bleaching) which then are grabbed by the halide (-ve) ions from the halide salt added to the mixture forming silver halide again (re-halogenation.) So now we have an image formed solely of silver halide.

Next step is to convert these halides back to silver and add some more in the process (intensification) using silver nitrate bath aided by exposure to UV.

D_Quinn said:

When the plate is immersed in the solution after the rehalogenation/bleach stage, it accelerates the aforementioned silver conversion process, leading to a higher concentration due to the presence of a significant amount of free silver nitrate in the solution, right?

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That part is right.

D_Quinn said:

The issue here is that once the silver atoms are formed, there is no issue. However, if silver halides remain on the plate, they can darken due to UV exposure, sooner or later. Therefore, it's better to fix to prevent this.

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Right.

D_Quinn said:

In the intensification process, once rehalogenation is carried out, all the silver halides on the plate need to be converted into silver atoms, otherweise, the remaining silver halides can darken due to UV exposure. Is that correct?"

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Correct. However, as I mentioned in a previous post, my guess is this may not be a big problem - image will darken somewhat but still retain the tonal relationship. Perhaps this can be taken into account by under-intensifying the image in silver nitrate bath. You can experiment by taking a plate, cover half and expose the other half in the Sun and check how the two sides differ. But you can also fix, why not?

D_Quinn said:

Additionally, during the rehalogenation/bleach stage, what is the role of bleaching? Does it reduce the number of silver atoms that have already been converted on the plate?

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See above.

D_Quinn said:

I apologize for asking many questions!
If you have the time to answer, that would be greatly appreciated.
Many thanks!

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No problems at all. This way I too learn as I ponder these questions.

:Niranjan.

Thank you very much! I'm learning a lot.
In my last intensification experiment, I used Potassium Ferricyanide instead of Copper Sulfate, but is my understanding correct that essentially the same thing (bleaching) is happening?

>The job of copper sulfate is to make silver (+ve) ions out of silver metal (bleaching) which then are grabbed by the halide (-ve) ions from the halide salt added to the mixture forming silver halide again (re-halogenation.)
This halide salt refers to Potassium Bromide, right?

Which of these chemicals is making the image whiter? In my previous experiment, the image did not become as white as the second photo (Rehalogenation/bleach stage) attached (this is not my work but I captured it from the video about Copper intensification just for reference).

In any case, the areas that were originally darker in the first photo (before rehalogenation/bleach) and turned whiter(during rehalogenation/bleach stage), those were formed purely by silver halide, is that correct?

Is this whitening effect caused by bleaching or rehalogenation? Or is it a result of both chemicals working together to become silver halide? (Meaning that both chemicals together create the whitening effect.)

If I fix this silver halide image (without performing silver nitrate treatment), will the image disappear? Or will parts of the silver atoms that haven't converted to silver halide remain?

>You can experiment by taking a plate, cover half and expose the other half in the Sun and check how the two sides differ.
Yes, I tested some of the negatives this morning. I put them under sunlight for about 3 hours. The negative that underwent rehalogenation/bleach became slightly darker due to sunlight exposure. Additionally, the negative that underwent rehalogenation/bleach followed by silver nitrate treatment also became slightly darker (to a level that is not easily noticeable). This might be because I diluted the silver nitrate concentration considerably (2%), so there might still be some remaining silver halide. Higher silver nitrate concentration speeds up the conversion to silver atoms, right?

>But you can also fix, why not?
Since I started this technique recently I haven't come across information suggesting that Copper Intensification (after silver nitrate treatment) leads to fixation, but I will definitely test it. Probably, people don't do it just because the impact of remaining silver halide on UV exposure isn't significant if silver nitrate treatment is conducted, or it might not be performed due to the added steps involved (including washing).

Thank you!!

D_Quinn said:

This halide salt refers to Potassium Bromide, right?

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Yes, that's the halide (the bromide, at least). The silver halide will then be silver bromide. This is indeed the compound that is formed from the silver image as you bleach it.

D_Quinn said:

Which of these chemicals is making the image whiter?

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The silver halide itself is mostly white - but how it looks, depends a bit. In your ferricyanide bleach, it will be a bit yellow, at least during bleaching, because of the yellow ferricyanide. Moerover, if you expose the bleached silver bromide image to strong (especially UV) light, it will at least partially 'print out' into a silver image. This tends to produce more pink and brownish hues. This fits with what you noted about exposing a bleached plate to sunlight.

D_Quinn said:

In any case, the areas that were originally darker in the first photo (before rehalogenation/bleach) and turned whiter(during rehalogenation/bleach stage), those were formed purely by silver halide, is that correct?

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Correct.

D_Quinn said:

Is this whitening effect caused by bleaching or rehalogenation?

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It's not an either/or question, really. 'bleaching' is the chemical term we use in this context for converting metallic silver (Ag) to a positively charged silver ion (Ag+). Well, physically, what really happens is that we 'steal' an electron from each silver molecule, leaving it one electron short, and that constitutes a positive charge. Such an ion tends to interact with other materials nearby, because (simply put) the silver ions will try to get their electron back, and they're prepared to associate with other ions with an excess electron if need be - entering a kind of nano-level time-sharing arrangement. In the instance of a rehalogenating bleach, the silver ions pair with negative charged halide (bromide, chloride, iodide) ions. These ions have an excess electron that they're willing to share with the silver ions. The arrangement only works if they (the silver and halide ions) remain close to each other - they're essentially holding hands by means of a shared electron.

As noted before, the white appearance is just the color of the silver bromide image. From the explanation above, you might glean that the whitening is the result of not bleaching or rehalogenation, but it's really the result of both happening at the same time.

In case you're wondering if you can also knock an electron off of a silver atom (making it into a positively charged ion) without the silver ion consequently entering a marriage with a halide ion: yes. That's what happens in a non-rehalogenating bleach. In this case, electrons are knocked off of silver atoms, turning them into silver ions, but in order to 'regain the use of their lost electron' (put in laymen's terms), the silver ions leave the plate and start dancing around in the bleach solution, where they (sort of) dance in pairs with dissolved negatively charged ions. As you can tell, it's a very similar process, but the net result for us, photographers is very different. With the non-rehalogenating bleach, the silver ions leave the plate (or film) and will wash away along with the used bleach.

D_Quinn said:

Additionally, the negative that underwent rehalogenation/bleach followed by silver nitrate treatment also became slightly darker (to a level that is not easily noticeable). This might be because I diluted the silver nitrate concentration considerably (2%), so there might still be some remaining silver halide. Higher silver nitrate concentration speeds up the conversion to silver atoms, right?

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As to the remark on speeding up: yes.
As to the phenomenon of the intensified plate also becoming darker: what you're seeing is indeed blackening of remaining silver halide. In my experience, intensification acts on the surface of the image. On images with a lot of silver on them (high optical density), it becomes very difficult or even impossible for the silver nitrate to break through the layer of silver that forms at the surface of the image during the first stages of intensification. If you look at such a plate through the backside (if it's coated on clear glass), you can see the pink/liver color of silver halide that's not entirely converted back to metallic silver. In practice it's usually not a problem with printing from such plates. The pink/brown/liver color tends to darken quite a bit on exposure to UV light, as you've noted. Even if some remains, it's usually still OK. What it does mean, is that there's usually a practical limit to the process of intensification. However, that limit occurs at such high optical densities that it's virtually never a practical limitation.

D_Quinn said:

Copper Intensification (after silver nitrate treatment) leads to fixation

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I never noticed this. I've intensified plates with copper sulfate (+ potassium bromide) followed with silver nitrate several times, also treating the same plate more than once, and there was always a dramatic density gain. I have to say I only did this on plates that were already fixed after development and thoroughly washed. Massive fog will probably obliterate the image if you do this process on unfixed plates.

But perhaps I misunderstood your remark and you intended to say that fixing after intensification is not necessary? In that case, I agree. There's no need for it.

PS: that image sequence matches my experience perfectly.

Thank you very much. It is getting much clearer than when I started.

>That's what happens in a non-rehalogenating bleach.

Does non-rehaloganating bleach in your remark mean Potassium Ferricyanide?

>But perhaps I misunderstood your remark and you intended to say that fixing after intensification is not necessary? In that case, I agree. There's no need for it.

Yes, that was what I meant.
But why there is no need to fix it after intensification (when the silver nitrate treatment is carried out to completion)?

Also, what do you think happens if I intensify a negative with copper sulfate (+ potassium bromide) but skip the silver nitrate treatment? This negative that I am talking about here is a negative that was properly fixed and washed before applying rehalogenation/bleach. Will the image formed of silver halide be washed away with a fixer?


As I mentioned I put some of the negatives under the direct sunlight and left it for two days. (For each negative I covered 2/3 of the image with a black plastic sheet to see any potential change in appearance; all negatives were properly fixed before the intensification and no varnish).

I noticed that the negative that was bleached only with Potassium Ferricyanide (no Potassium Bromide) has the biggest effect on UV. The uncovered area (where was exposed to UV) became slightly darker (denser).

Also, I noticed the one which was treated with rehalogenation/bleach/silver nitrate also has a slight change. The uncovered area turned a bit thinner. Why??

I noticed a slight color change but not in density on the negative that was not applied any intensification.

Do you have any clues for these changes in density?

D_Quinn said:

Does non-rehaloganating bleach in your remark mean Potassium Ferricyanide?

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It could, but there are several non-rehalogenating bleach options. Usually we use something like potassium permanganate or dichromate for this. For your application, this is not really a very relevant direction. It's something used in e.g. reversal processing (slide film etc.)

With a ferricyanide-only bleach (no bromide), the silver image turns into silver ferrocyanide. This is technically also not a silver halide, so it's a non-rehalogenating bleach. This silver ferrocyanide is actually the intermediate compound that also forms initially if you use a ferricyanide + bromide bleach, but the silver ferrocyanide turns into silver bromide immediately.

I think you could actually bleach a silver image with a ferricyanide, turning the image into silver ferrocyanide, and then wash the plate in a separate potassium bromide bath to turn the silver ferrocyanide image into a silver bromide image. I've never tried this, though. I don't think there's much practical use to it since it's easier and quicker to just mix the ferricyanide and bromide in the same bleach and do the bleaching process in a single step.

D_Quinn said:

But why there is no need to fix it after intensification (when the silver nitrate treatment is carried out to completion)?

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Because there's no more silver halide that doesn't make up the image.

When you've just exposed (in the camera) and developed your plate, there will be the silver image on the plate, along with a lot of unexposed and undeveloped silver halide. You need to get rid of this (but not the image) because otherwise you end up (over time) with a plate that's covered in an even, featureless layer of silver. The image will no longer be visible. So that's what the fixer is for.

In the intensification process, all non-image forming silver and silver halide has long gone, because it was fixed out when the plate was initially processed. So you don't have to worry about it anymore. Nowhere in the intensification process silver halide is deposited on the plate where there's no image. So no fixing is necessary.

D_Quinn said:

Will the image formed of silver halide be washed away with a fixer?

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Yes. If you bleach a plate in a rehalogenating bleach and then fix it, everything will be gone. This is in fact what happens in for instance color processing. A color negative has no silver in it anymore, but a silver image is initially formed because it helps to create the colorful dye image (simplifying matters a bit). To get rid of the silver image, which isn't desired in the final negative, the film is bleached in a rehalogenating bleach, and ultimately fixed. If there would be no color dyes in that film, all that would be left, would be blank film.

To illustrate, here's a piece of B&W 35mm film I treated along these lines (because someone didn't believe bleaching will actually remove the image):


This was a strip of rather thin B&W negatives (expired Fomapan 400). I dropped some ferricyande + bromide bleach onto it, and then some fixer. As you can see, all silver (image) is gone in the place where the bleach acted on the image. The same would happen to a plate that you would initially bleach and then fix. It'll jut go blank.

D_Quinn said:

The uncovered area turned a bit thinner. Why??

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I don't know exactly; I'd expect the silver bromide image to also turn darker/denser, to be honest. I do quite a bit of bleach & redevelop with a dichromate bleach and when I expose the silver chloride image (which is sort of similar to silver bromide in many ways) to strong UV light, it turns noticeably darker/brown. This is because the silver halide prints out.
What happens to a silver ferrocyanide image (the ferricyanide-only bleach you also tried) when exposed to light, I don't know. I suspect it also allows the silver to 'print out' into metallic silver, but I'm not sure what happens to the ferrocyanide ion. Perhaps @nmp can comment on this.

So why you're seeing a seemingly reverse effect of a silver bromide image turning thinner/lighter upon UV exposure, I can't explain. As far as I can tell, it's not supposed to happen. I wonder if it may be an observation issue where a thin silver image on a glass plate may appear to be less dense than a silver bromide image, because the silver bromide is lighter in color, but in reality I suspect that the plate really has gained optical density. Basically, I suspect your eyes play a trick on you in this case.

koraks said:

What happens to a silver ferrocyanide image (the ferricyanide-only bleach you also tried) when exposed to light, I don't know. I suspect it also allows the silver to 'print out' into metallic silver, but I'm not sure what happens to the ferrocyanide ion. Perhaps @nmp can comment on this.

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I would say the same. I guess ferrocyanide will have to find someone else in the matrix to mate to. It is probably not as sensitive as a halide so slower to darken.

Now I remember where we discussed similar issues - in was in a thread about blue toning.

koraks said:

So why you're seeing a seemingly reverse effect of a silver bromide image turning thinner/lighter upon UV exposure, I can't explain. As far as I can tell, it's not supposed to happen. I wonder if it may be an observation issue where a thin silver image on a glass plate may appear to be less dense than a silver bromide image, because the silver bromide is lighter in color, but in reality I suspect that the plate really has gained optical density. Basically, I suspect your eyes play a trick on you in this case.

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Perhaps there is bronzing or solarization going on at that stage with any new silver formed. The image might seem lighter in that case, particularly if it was dominated by higher density areas.

:Niranjan.

nmp said:

Now I remember where we discussed similar issues - in was in a thread about blue toning.

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Man, my memory is toast. Thanks for reminding me!

nmp said:

Perhaps there is bronzing or solarization going on at that stage with any new silver formed. The image might seem lighter in that case, particularly if it was dominated by higher density areas.

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Yes - I do see something sort of similar when chromium intensifying negatives. It's usually during the final stages of bleaching, on rather dense negatives, and it's temporary. It's not really a density difference; just a way how it image looks under reflected light under very specific conditions.

What we see in these silver- and silver-derivative images is really complex much of the time.

Thank you for your advice and also the photo. It helps a lot!

>So you don't have to worry about it anymore. Nowhere in the intensification process silver halide is deposited on the plate where there's no image. So no fixing is necessary.

My understanding was that the silver atom that was made in the initial process of negative making becomes silver halide through Intensification. And with the Silver nitrate treatment, I thought that silver halide turns into the silver atom. However, depending on the concentration of silver nitrate and the duration of immersion in the solution, is there any silver halide that doesn't completely convert to a silver atom?
I wondered whether silver halide that didn't fully become silver needs to be eliminated during the fixing process after the silver nitrate treatment. No?



> >What happens to a silver ferrocyanide image (the ferricyanide-only bleach you also tried) when exposed to light, I don't know. I suspect it also allows the silver to 'print out' into metallic silver, but I'm not sure what happens to the ferrocyanide ion. Perhaps @nmp can comment on this.
For the silver ferrocyanide image (the ferricyanide-only bleach), the density of the portion exposed to sunlight increased. I have no idea.

As for the silver bromide image, it's quite puzzling. If I look at this negative up against a ceiling light, the top 1/3 of the negative that was exposed to the UV appears less dense. But when placed on white paper or black velvet, or directly on a lightbox, the difference in density wasn't as noticeable (although I feel there is a difference). As you pointed out, silver bromide looks lighter, so it might be influenced by the surrounding light.

By the way, for this plate, I immersed it in the rehal.bleach solution for about 3 minutes, followed by washing for 2 minutes (tap water), and then immersed in the 2% silver nitrate solution for 7 minutes, followed by washing for 10 minutes. Do you think this time distribution is reasonable (I am aware there is no fixed rule about it though)?



Also, I discovered another puzzling thing about the same plate above.

When comparing a negative without Intensification (the left column in the image) that was exposed with the exact same exposure of the aforementioned intensified negative (the left column), surprisingly the Intensified negative appears slightly less dense (on the lightbox). Also, I also made contact prints (gelatin silver in darkroom) and placed them on top of the corresponding negatives. The exposure time and filter (0) were the same during printing. However, when placed them on black velvet, the Intensified negative noticeably appears brighter. I can't understand how the Intensified negative looks brighter despite its density being reduced due to Intensification. Could it be that the silver bromide's brightness is causing this effect (eye trick)? Although this effect is more convenient for me it led to another mystery. Also, I wonder if I can maintain this brightness or not.

D_Quinn said:

is there any silver halide that doesn't completely convert to a silver atom?

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Even if there is, you wouldn't want to remove it by fixing, because it will just remove density that you just tried to gain by intensifying the image. You would want to leave it where it is, allowing it to convert to metallic silver over time due to UV exposure.

Those illustrations of the different plates are really excellent! They show perfectly what you described before.

D_Quinn said:

For the silver ferrocyanide image (the ferricyanide-only bleach), the density of the portion exposed to sunlight increased. I have no idea.

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Yes, my guess is that the silver ferrocyanide also prints out in a similar way that silver bromide does.

D_Quinn said:

As for the silver bromide image, it's quite puzzling.

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Yes, it is. The plates I treated in the way you described, would have the silver image turn black upon intensification in the silver bath. It almost looks like nothing much is happening in the silver nitrate bath. Do you see anything happening to a plate that's been previously bleached in a rehalogenating bleach as you put it into the silver nitrate bath?

D_Quinn said:

Do you think this time distribution is reasonable (I am aware there is no fixed rule about it though)?

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Yes; in fact, the intensification in the silver nitrate bath in my experience happens more or less instantly - within a few seconds. The difference should be very dramatic and immediately visible. If nothing (much) appears to happen as you put the plate into the silver nitrate bath, then the process for some reason isn't working.

D_Quinn said:

Also, I discovered another puzzling thing about the same plate above.

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The 'intensified' plate really looks like a pure silver bromide image to me that has not actually been intensified - just bleached. This is more evidence that the intensification is probably not happening. The plate would look very different - and it wouldn't work as an ambrotype anymore.

Can you tell a bit more about the 2% silver nitrate solution you've used for these experiments. Is it just silver nitrate in distilled water? Have you added any nitric acid etc? In my case, I used to use a very weak silver nitrate solution (probably less than 1%), but I had added a little nitric acid to it. I don't know if that makes a difference, but it worked that way for me.

Thanks for your comments!

Yes, I watched some YouTube videos and thought that the silver bromide image would change to black, but it didn't. Here are four negatives shot at the same exposure, with different post-processing (prior to the UV exposure test).


For the top row, I put a small strip of newspaper between the negatives and the white paper just to the right of my face (to see the density difference).
You can see that the silver nitrate-treated negative on the very left has a slightly higher density than the other three negatives.
However, intensification with silver nitrate may have little effect as you say, as is evident from the ambrotype-like appearance.

The silver solution that I prepared was:
2g Silver nitrate
150ml distilled water

Note:
The solution was not exactly the 2% as you can see above (1.3%).
I prepared it right before the treatment (no nitric acid was used).
For the treatment, I didn’t pour it on the negative but filled it in a small black tray.

As to 345 (the image on the very left), after the rehal.bleach treatment, I put the negative in the silver solution and waited to change in density. The dense area (background) slowly became brighter gradually (I used a black tray).

Do you get any clues from the process not working properly?

Thank you!

To intensify negatives, I'm also considering trying intensification using copper(II) sulfate instead of ferricyanide. I've found that there are two products available: copper(II) sulfate pentahydrate and copper(II) sulfate anhydrous. Which one should I use?

D_Quinn said:

To intensify negatives, I'm also considering trying intensification using copper(II) sulfate instead of ferricyanide. I've found that there are two products available: copper(II) sulfate pentahydrate and copper(II) sulfate anhydrous. Which one should I use?

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You want pentahydrate. Anhydrous is hygroscopic.

:Niranjan.

Thank you very much!!