Avoiding potassium dichromate in bromoil process

[Wayne]

Wayne, the Hydroquinone would be part of a specially formulated developer, not part of some bleach. There are two common ways to achieve selective tanning:

1. Use any developer to develop the image, then use a bleach which tans gelatin wherever metallic silver was bleached. That's the approach chosen by the process using the dichromate bleach.
2. Use a developer which tans gelatin wherever development takes place. This is what Pyrogallol, Catechol, and apparently also Hydroquinone based developers can do, if they are formulated correctly. No bleach should be necessary here as long as the developer creates sufficient tanning.

PS: I have never done this process, so I would be the very last one to be asked for sample recipes. Ned's blog appears to be what you should be looking at, and the two links I provided in this thread point towards HQ based tanning developers which have at least been tried.

I did a fairly meaningless experiment last night, just to see what happened and to use up some old stock. Using the hydroquinone/sodium carbonate version of Pyrocat-HD linked to above, I took 175 ml of Part a and 250 ml Part B and added 500 ml water. My rationale if you can call it that was just to get in the ballpark of 10grams HQ and 40-50 grams carbonate/liter just to make sure I got an image with the least time wasted. I don't know what amounts would be desirable for best tanning. I only made 2 test strips and one "final" print. I was pretty darned pleased with the image, but as expected the solution oxidized rapidly in the tray turning almost black in 15 minutes. I used Oriental RC paper, which isnt suitable for bromoil but seemed adequate for this quick experiment to see if I could get a useable print developer. Anywho I got apretty nice warm toned image with good contrast that was overall quite pleasing, but a fair bit of general stain too on the borders. I'm not sure if a couple grams of sulfite would have reduced the general stain or prolonged its life, but I knew any more than that would prevent image stain so I didn't add any. I'm not sure if this method has any actual potential but I was bored and needed to get rid of some solutions before heading away from my darkroom for a month or two.

 

[Gerald C Koch]

The bromoil process requires the selective hardening of the gelatin. In addition the hardening must be sufficient to withstand the wear and tear inherent in the process. While there are other tanning agents I doubt that they can satisfy these two requirements satisfactorily.

While dichromates can be dangerous observing the usual safety precautions by the use of gloves and goggles while handling it or its solutions should suffice. While working with the solid a dust mask is recommended. The main danger is from ingestion and not from dermal contact. So don't eat the stuff. Avoid any spills. Don't inhale any dust. There are far worse toxins around. People in northern Europe grow Aconite in their gardens. A plant with attractive purple flowers. The common names are Monkhood or Wolfsbane. Even casual contact with plant can cause toxic symptoms or even death. Two milligrams of the toxin are considered lethal in all cases. Yet it has been used as a folk remedy.

So if you wish to do bromoil you will just have to put up with the problems inherent in using dichromates. Bronoil IS an alternative process.

 

[Gerald C Koch]

I personally have no problem with old threads popping up again. It shows that people are using the APUG achieves. There is nothing more annoying than threads that start out with "I know that this question has been asked before, but ..." Well then, exercise those fingers.

 

[Wayne]

Avoid any spills.

Yeah, and who has ever had a spill before?

I have no problem with other people using dichromates, but I'll be the one deciding whether I use it or not. I've chosen to avoid it and some of the other more toxic compounds where I consider the risk higher than necessary to make my so-called "art". If I never make a bromoil print or a pyro negative because of it, I'm fine with that because I'll also not have to worry about making a dangerous mistake.

The bromoil process requires the selective hardening of the gelatin

What were you getting at here? That general stain is undesirable? That much I know, but if you meant something else please explain. That's mostly why I posted my results, to see if anyone had a suggestion for reducing the general stain. I went back and looked at my test strips and the first one showed little general stain, but the second one made just a few minutes later did.

 

[NedL]

Wayne, I think you are on an interesting path. Your idea is to achieve the selective hardening during development of the print rather than after the print has been developed. I don't want to speak for Jerry but I think his comment was simply a general one and true: the main objective is to obtain selective hardening of the gelatin, there aren't that many ways to achieve it, and to work well for bromoil it needs to be robust. That's pretty hard to do! I know with my own experiments, I always get some gelatin relief image, but the ones that are really strong are easier to ink. There seem to be a lot of variables at play and sometimes I get a strong relief and sometimes a weak relief after seemingly repeating everything the same... this tells me there is at least one critical factor ( temp, humidity? I don't know! ) that matters a lot but that I'm not controlling.

BTW I also don't use dichromates, mostly because I don't know how to deal with waste (including washes ) ...

 

[pdeeh]

I have no idea if this is relevant, but ... Dead Link Removed

 

[Gerald C Koch]

Wayne, I think you are on an interesting path. Your idea is to achieve the selective hardening during development of the print rather than after the print has been developed. I don't want to speak for Jerry but I think his comment was simply a general one and true: the main objective is to obtain selective hardening of the gelatin, there aren't that many ways to achieve it, and to work well for bromoil it needs to be robust. That's pretty hard to do! I know with my own experiments, I always get some gelatin relief image, but the ones that are really strong are easier to ink. There seem to be a lot of variables at play and sometimes I get a strong relief and sometimes a weak relief after seemingly repeating everything the same... this tells me there is at least one critical factor ( temp, humidity? I don't know! ) that matters a lot but that I'm not controlling.

BTW I also don't use dichromates, mostly because I don't know how to deal with waste (including washes ) ...

Thanks I should have explained a bit more. The amount of hardening from a staining developer would probably not be enough to withstand the rigors of the bromoil process. Staining and hardening are two distinct things. While there is some hardening with a staining developer the object is to produce a stain image and not to harden the emulsion. Hardening here is an accidental byproduct of image formation.

Bromoil has been around so long that one could assume that any alternative hardening method has already been tried.

I agree with Wayne. I have absolutely no desire to make Daguerreotypes and have to work with boiling mercury. Old time practioners of the art would notice that their gold watch chains had turned silver from the mercury fumes by the end of the day. They also experienced a shorter than expected lifespan. Mercury salts are used in the manufacture of felt hats. In sub-lethal amounts mercury causes brain damage. Hence the very true expression "mad as a hatter." However hexavalent chromium is not a cumulative poison as are mercury or pyrogallol. Its danger lies with chronic exposure. In the cell hexavalent chromium is reduced to trivalent chromium which is small amounts is a necessary trace element. Any cell damage occurs during the reduction of Cr+6 to Cr+3. The damage being caused by the formation of pentavalent chromium.

 

[NedL]

I think DAS is relevant -- although maybe more to oil prints like I'm trying to make than to bromoil. There are threads on APUG about using it for carbon transfer.

Over the past few months I've been completely immersed in salt printing, and haven't done any more experiments with AFC gelatin relief images, but I ran across a couple of related patents that are interesting. These patents were about making gelatin relief images for other uses like etching or direct gelatin plate making for presses. One of them used AFC or other ferric salts ( +a reducing sugar supposedly increases speed ), exposed to UV under a negative, and then "developed" with heat alone. Another also used heat after initial hardening caused by ferric to ferrous reduction. When I read these patents, it sounded to me like heat might be a promising way of enhancing the hardening if it's too weak.

With bromoil, sometimes people don't soak the matrix long enough before inking, so that the unhardened gelatin doesn't swell enough and reject the ink. With my AFC reliefs, I sometimes have the opposite problem: if I soak the matrix too long, the hardened areas also swell a little, and do not accept the ink well enough. This fits with what Jerry wrote, and dichromates work really well for this purpose. When we play around with various alternatives, we're trying to do what is already a difficult process starting at a disadvantage. Can = challenge/fun for someone like me, = frustration if you want results

 

[Wayne]

Are we certain that developer hardening is not robust enough to survive the bromoil process or are we just assuming that because nobody does it? It seems like a pretty good assumption, but I've been burned by assuming things before. There should be some published record or oral memory among bromoilists that Josep Kruttzenwiegercyzky tested this in the 1880's, for example. Unless its just such common knowledge that nobody bothers to mention it.

I'm pretty much out of my element on these topics, but a quick Google turned up a patent that calls developer hardening "comparatively rugged and durable" although I don't know what its being compared to. Since I have never done bromoils I also don't have a sense of just how "durable" the relief must be.
https://www.google.com/patents/US1923764

 

[NedL]

Nope not certain! I think you should go ahead and try it. The reason I mentioned heat in my post above was that if you find the hardened areas are not hardened enough, it might be worth a try ( the patents mention heating in an oven or in front of a heater, to a point that is lower than would make the gelatin melt... I don't recall what temperature exactly, but it was relatively low for an oven, like 150 or 175. The older patent just mentioned holding it in front of a radiant heater, and implied that the changes to the hardened areas would be visible. ) Good luck and have fun!

 

[Wayne]

Unfortunately I won't have a darkroom for a couple months.

 

[falotico]

but a quick Google turned up a patent that calls developer hardening "comparatively rugged and durable" although I don't know what its being compared to. Since I have never done bromoils I also don't have a sense of just how "durable" the relief must be.
https://www.google.com/patents/US1923764

Troland who is the inventor in this patent is one of the great names in color photography. Not only did he develop the tanned-gelatin relief method of dye-transfer used by the Technicolor Company, he held the patent for mono-pack color film which was eventually used to replace dye-transfer in motion pictures.

This patent uses both pyrogallol and dichromate to harden the gelatin. It produces an essentially grain-less image in color. This two-hardener process was eventually abandoned by Technicolor but prints of films which used it still survive--"Nothing Sacred" 1937 for example.

 

[cliveh]

When I read these patents, it sounded to me like heat might be a promising way of enhancing the hardening if it's too weak.

With bromoil, sometimes people don't soak the matrix long enough before inking, so that the unhardened gelatin doesn't swell enough and reject the ink.

It may also be worth mentioning that the soaking time is also dependent on the temperature and vice versa to get the differential of hard and soft gelatin within the print.

 

[Gerald C Koch]

Using a pyrogallol developer for its tanning capabilities rather than dichromate is really trading one poison for another. Pyrogallol is a cumulative poison which attacks the nervous system causing tremors and loss of motor control. LDLo (lowest lethal dose): Oral 28 mg/kg.

 

[Wayne]

I agree, that's why I'll only use hydroquinone. I won't use dichromate OR pyro. Hydroquinone must be treated with care too but its much less toxic than pyro. Some have tried to argue otherwise (always pyro proponents) but I've researchd it pretty well and satisfied myself with that conclusion. I've seen conflicting numbers for LD50 but I know its toxic to aquatic organisms and I also know it breaks down fairly quickly in sunlight and in the environment and I know to be careful with the dry product and not drink or dip bagels in the wet one.

 

[NedL]

It may also be worth mentioning that the soaking time is also dependent on the temperature and vice versa to get the differential of hard and soft gelatin within the print.

That's a good point Clive and what I wrote above was also true for temperature. I.e.: Some bromoilists find that they need warmer water to swell the unexposed gelatin enough to reject the ink. With my weakly hardened reliefs, if the water is too warm the hardened areas also start to swell and won't accept the ink.

You can imagine how much frustration this led to! Of course I had read all about bromoil before I started, and the advice to soak longer or in warmer water just led me to more and more trouble. Being inexperienced, I didn't understand at first what was going wrong. I didn't start getting good results until I realized what was happening and that I needed a short soak in cool water!

Another weird thing about gelatin relief is that once it's been soaked and swelled in warmer water, it will continue to swell to that new higher level of swelling from then on, even in cooler water. In my case that meant once I'd soaked it in water that was too warm, it was doomed, and nothing could ever be done to salvage it.

 

[Rudeofus]

Hydroquinone must be treated with care too but its much less toxic than pyro. Some have tried to argue otherwise (always pyro proponents) but I've researchd it pretty well and satisfied myself with that conclusion.

The main problem with pyro is not so much its toxicity (which is represented by LD50), but that it's absorbed through the skin. Skin exposure is a much more common occurrence in typical dark rooms than ingestion or inhalation.

 

[Wayne]

I did a fairly meaningless experiment last night, just to see what happened and to use up some old stock. Using the hydroquinone/sodium carbonate version of Pyrocat-HD linked to above, I took 175 ml of Part a and 250 ml Part B and added 500 ml water. My rationale if you can call it that was just to get in the ballpark of 10grams HQ and 40-50 grams carbonate/liter just to make sure I got an image with the least time wasted. I don't know what amounts would be desirable for best tanning. I only made 2 test strips and one "final" print. I was pretty darned pleased with the image, but as expected the solution oxidized rapidly in the tray turning almost black in 15 minutes. I used Oriental RC paper, which isnt suitable for bromoil but seemed adequate for this quick experiment to see if I could get a useable print developer. Anywho I got apretty nice warm toned image with good contrast that was overall quite pleasing, but a fair bit of general stain too on the borders. I'm not sure if a couple grams of sulfite would have reduced the general stain or prolonged its life, but I knew any more than that would prevent image stain so I didn't add any. I'm not sure if this method has any actual potential but I was bored and needed to get rid of some solutions before heading away from my darkroom for a month or two.

Turned out to be 3 months away. All the better.

So if I was to travel farther down this probable dead end attempting to selectively harden the print sufficiently using only hydroquinone developer, how should I go about it? I only used the developer formula quoted above in order to get an image; I have no idea how effective it would be for tanning, or how I might improve it before even starting. More Part A? Less? The same? A few grams of sulfite so it doesnt die or increase general stain quite so quickly? Is the phenidone working with me, against me, or neither?

Then on to the bromoil process itself. It probably would be helpful if I'd actually done bromoil, lol, (dya think?!) but I haven't for reasons already stated. Using these instructions as a starting point,

http://unblinkingeye.com/Articles/Brom/brom.html

Would I just modify step 3 using my developer, and then omit steps 7 through 10?

 

[NedL]

I just got some copper sulfate, with the idea of using it to bleach some prints ala bromoil and try a few ideas about hardening. I also am playing with another process and need a bleach step.

Two questions:

1) why do they use copper sulfate instead of pot-ferri for bleaching bromoils?

2) I know that some people make bromoils from modern "super hardened" paper, but I don't know what the trick is. It would be nice to be able to run some tests w/ inexpensive paper. Maybe this will all wait until I make some gelatin emulsion, which will probably happen before pigs grow wings....

 

[Wayne]

I just got some copper sulfate, with the idea of using it to bleach some prints ala bromoil and try a few ideas about hardening. I also am playing with another process and need a bleach step.

Two questions:

1) why do they use copper sulfate instead of pot-ferri for bleaching bromoils?

2) I know that some people make bromoils from modern "super hardened" paper, but I don't know what the trick is. It would be nice to be able to run some tests w/ inexpensive paper. Maybe this will all wait until I make some gelatin emulsion, which will probably happen before pigs grow wings....

Looks like we'll both just have to blaze our own trail.

 

[removed account4]

Try reading the conversation that ensues after this post: Dead Link Removed

Gives ya an idea regarding dichromate.

finally reading this thread again
and the dichromate article is gone
anyone know where it might have popped up?
unfortunately mr peabody, sherman and their way back machine
can not help due to robot txt whatever that means ...

 

[Wayne]

finally reading this thread again
and the dichromate article is gone
anyone know where it might have popped up?
unfortunately mr peabody, sherman and their way back machine
can not help due to robot txt whatever that means ...

A site's robot txt tells search engines whether to archive the site or not.

 

[removed account4]

i guess its lost forever then

 

[NedL]

i guess its lost forever then

No, it just moved.

You can find a copy here: http://www.bostick-sullivan.com/blog/?p=1113
Start reading at the entry: "I am not a member of the Green Party"... and continue to read the 'Appendix D'.

The appendix is also available in Dick Sullivan's carbon printing book, which is available online here:
http://www.bostick-sullivan.com/articles/modern_carbon_sullivan.pdf

 

[NedL]

By the way, in case anyone is interested, the process I've been working on is like the oil print process in Dick Sullivan's blog entry referenced above, but using AFC ( ammonium ferric citrate ) AKA FAC ( ferric ammonium citrate ), yes that's the stuff used in cyanotypes. At one time I had a blog here at APUG about my progress. The oil print process uses a full-sized negative and the gelatin is hardened where light hits the paper. A bromoil, on the other hand, starts with an enlarged print, and the gelatin is hardened in proportion to the silver in the gelatin ( areas that were dark on the print are hardened more ). Using AFC to make an oil print is tricky and difficult, and the hardening is not as robust as with dichromate salts.

If you are a subscriber, you can see one result in the gallery here: (there was a url link here which no longer exists)

Some thoughts about dichromates:
( this is just my own opinion... I'm not trying to tell anyone else what to think or do! )

I am on a well and septic, and have decided not to use dichromates here for several reasons. One simple reason is that I've already got waste streams of used fixer and toners, silver nitrate, and gallic acid. It's under control and does not generate more waste than I can easily deal with, but I didn't want to add yet another waste stream to deal with. Another reason is that after reading the appendix above, I was left with some questions that I don't know the answers to:

1) how would I know that all the hexavalent has been converted to trivalent? ( and could the amount remaining be enough to matter? )
2) how would I know that all the trivalent has been precipitated as chromium oxide? ( and does this really matter? )
3) how would I know that the chomium oxide has all been filtered out ( or does that even matter? )
4) what about wash water? After the developing stages that use hexavalent chrome, there will be a series of washes. At what point is it safe to ignore the amount of dichromate being washed out, or does ALL the wash water need to be treated ( could be a large volume! ).
Bromoil instructions often say to wash until the yellow dichromate stain is cleared, so obviously dichromate continues to be washed out during the wash stages... is it enough to worry about, would you really do this in your kitchen sink? (of course not, just sayin )
5) what about the physical print itself? There will be some dichromate left in the gelatin ( a common complaint in bromoil is that the matrix doesn't perfectly clear after the bleach/tan steps...). Presumably it's "locked in" and quite safe, but how do we know? Does this matter?

At the end of the day there will be a large quantity of water, and it needs to go somewhere. It could go into my septic or it could get poured on the ground. My hunch is that we're talking about such small quantities and large dilutions that all of these questions have reasonable answers, and that you could probably just go ahead and the residuals will be so dilute that they can just go into the septic. But since I don't actually know the answers, I decided to let it be.

So there's a long-winded explanation for why I don't use dichromates here at my house. I have no fear of actually using them... only concerns about managing the waste, which are a) I don't know enough to know what is safe, and b) it sounds like a lot of trouble and fuss, even if it can be done safely and responsibly.