Bromoil copper rehal bleach not working

[CTwist]

I am trying my hand at bromoil and have met an obstacle, for which I am struggling to find a solution in all my readings. I will give more info on my process below, but this is the nub of it. I am using the Venn two-bath approach to bleaching and tanning. When I put the print in the first bath at 20 degrees C (CuSO4 95g/L + KBr 5g/L), the print does not bleach. I occasionally get a bit of bleaching in darker areas of the print, but even after an hour, I have little to show for myself. How long should it take to bleach? Any offers on what I can change to make the bleach work?

More info:
(i) the print comes from a reversal processed silver gelatin paper - a process at which I am adept. After the metabisulfite bath to clear the bleach, I wash for 15 minutes in running water. I presume this clears all the salts. I then redev in paper dev diluted 1:9 in water. When a high-key image is present, I stop and fix it. I then wash again for 15min in running water, before proceeding to bleaching & tanning.
(ii) I first tried the one bath solution (CuSO4 + KBr + K2Cr2O7), but I didn't get anywhere. I added sulfuric acid (which seems to be optional) and then this bath cleared the image. The result was a brown ghost image, which did not disappear after fixing. I dried it, soaked it and inked it up, but no image structure appeared. Not knowing where the problem lay, I opted for Venn's two-bath approach, which immediately showed the first problem was with the bleaching.
(iii) the paper that comes out of the reversal process, is totally white before I redev it. There is no brown ghost image at that stage.
(iv) when the bleach did work a bit on the darker parts of the image, out of curiosity, I put the print in the second of Venn's baths (KBr + K2Cr2O7). This resulting in the image bleaching entirely. When I dry, soak and ink up this print, I get a pigment image where there had been bleaching in Venn's first bath. This proves to me my ability to tan the gelatin and also to ink up an image. I need to sort out the bleaching stage.

Thanks for your help and insights, Charles

 

[NedL]

Welcome to APUG!

I can't offer any advice from experience, but it seems to me that you might be able to simplify things to isolate where the problem is coming from.
Maybe you have already tried these things, IDK.

1. Try the Copper Sulfate bleach on a print that has been processed normally. See if you can bleach, tan, and ink. If this works, then you know that your basic materials are not the cause of trouble.
2. Try again on one that has been redeveloped only.
3. Finally try on one one that has been reversed.

Good luck!

 

[ced]

I have no experience with bromoil but perhaps a different paper may solve the issue.

 

[GregW]

Charles, I find with a really high key image with very rich blacks the Laughter formula does leave a faint brown after image which only slightly lightens with fixing which has no effect on the final product. are you using a non hardening fix? Which paper are you using? Ink? How long are you soaking prior to inking and at what temperature is the soak water?
I agree that you should first nail down bromoil on a normal print then move to reversal processed one. You've got a lot of variables added to an already finicky process.

 

[CTwist]

NedL - Suggestion 1 = very sensible. I'll get on to it. Suggestion 2, I am struggling to understand: how can I redev the print, outside a reversal process? Sorry - not sure what you are referring to.

ced: Should have said, it's Foma 112, which seems to be the only recommended paper readily available in the UK.

GregW: I had thought a print was a print was a print. I am discovering not so. From my readings, I am lead to understand that the faint, brown image is silver sulphide, ie a sepia image. It seems that the sulphide can be produced when over-dev'ing, which I strove to avoid. I am also wondering if the oxidisers (CU2+ and Cr2O7), the silver and one of the various sulphur-based compounds (sulfite, bisulfite, metabisulfite, thiosulfate and sulfate are all present at one stage or another) could not react to produce the silver sulphide. Given the various reactions of Cu2+ with said sulphur-based compounds, I am inclined to launch a big S hunt and wash harder.

How long should the print typically take to bleach in the copper rehal bleach? That's the one bit of key info that is never mentioned.

Thanks!

 

[GregW]

Charles,
I'm weak on chemistry. I would start with a conventional print, ie: expose, develop the positive image, stop and fix*. wash it forever. let dry. soak 5 minutes. The Laughter bleach formula should take between 7 and 10 Min. constant agitation. Don't go beyond that. Wash some more. *Fix can not have a hardener in it. I use plain simple fix. Wash the hell out of it. after it dries on it's own soak it again and let air dry, toward the end of drying this time finish with a hairdryer and dry the hell out of it, you want it to be very crisp feeling. Rolled up most likely. Now soak in warm water for a bit, how hot or warm will take experimenting, how long will take experimenting. now ink etc.
Occams razor your process, once that's sorted then slowly reintroduce complications.
good luck,
greg

 

[cliveh]

Try this:-

Copper Sulphate 113.4 gms
Potassium Bromide 113.4 gms
Potassium Bichromate 5.12gms (missing from your formula)
Sulphuric acid conc 6.4 gms (also missing from your formula)

Distlled water to make up approx 2 litres.

 

[ced]

Got you on the Foma paper, so it could be that the fixer has a hardner which is not helpful.

 

[CTwist]

Thanks Greg for the times and advice.

Fixer is thiosulfate at 100g/L and nothing else, in order to avoid any problems with hardening agents.

CliveH: thanks for the formula. I do mention those compounds. Only confusion might be I said K2Cr2O7 rather than dichromate. I would have to check your concs against mine, but I guess they are not far off.

I suspect insufficient washing. Can sulfite be used to chase metabisulfite in the same way it helps the removal of thiosulfate?

 

[ced]

The folks here may be familiar with your problem, they are also in your neck of the woods...
http://thebromoilcircleofgreatbritain.com/

 

[CTwist]

I have done some more work and have bought a new lot of CuSO4 from a different supplier in case there was a contaminant in the first lot. I have tried to bleach a piece of photo paper produced by more traditional means. I didn't have the courage to set up an enlarger so I simply took a piece of photo paper, put it in some dev and exposed it to light until it was mid-grey; then fixed in 10% thiosulfate and washed for a couple hours. I prepared the copper-based rehal bleach by dissolving 19g of CuSO4 and 1g of KBr in 200ml of water. At 20 degrees C, there was no bleaching to be seen, whichever lot of CuSO4 I used.

What am I missing?

 

[cliveh]

Are you sure you are using a paper that has no supercoat?

 

[CTwist]

It's Fomabrom Variant 112 Matt. I believe it doen't have a super-coat but couldn't swear to it.

 

[GregW]

Try 70ml of Copper sulfate@10% and 70ml of Potassium bromide @10% in 860ml water. see if that does anything.

 

[ColinRH]

I've been making some bromoils on and off since only last October but seem to have a bit of grip on it.
The main advice I might offer is to follow the directions from the Bromoil Circle of GB. They are not very detailed but the directions are there.
Like you I use Foma 112. Make a 'normal' print and then give 1 stop extra exposure with 1/2 a grade softer. That's a good starter and should get you going.
Do the usual dev - fix (2 x 10% hypo at 2 1/2 mins) - HCA - and good wash. Dry. (I don't know why the paper has to be crispy dry when you are only going to re-wet it , but there you are, its what you have to do!)
Use bleach/tan as:- 1) 50g copper sulphate + 500ml water 2)50g potassium bromide + 500ml water 3) 5g potassium dichromate + 500ml water (see Ed Buffaloe on Unblinking Eye). I DON'T use sulphuric acid
Soak print for whatever you need - I use 20C for 5minutes then bleach - I use up to 15 minutes at 20C. If you make the shadow areas too dark they will not bleach out and will remain reddish but for practicing it makes no difference, you can still try it. Fix again (2 x 10% hypo at 2 1/2 mins) - HCA and wash. DRY.
I then re-wet at 25C for 5 mins dry off with chamoix or kitchen towel and then ink - it works.
Then do as NedL says, start simple and then try your own thing.
Hope you are getting some success - its an odd process but really can make some prints very appealing. When I started I had never seen one so had no real idea of what to expect.

Sorry its a bit long everyone.

 

[CTwist]

Update...
Having given CuSO4 up as a bad idea, I decided to run the original CW Piper chemistry (different redox coupler). That worked a treat in terms of getting a grey-green ghost image. But inking up proved an obstacle, until I ran more drying steps - thanks ColinRH for insisting on that. What drying does, is to allow the strands of gelatin to settle and form a close network, making them therefore easier to tan (aka crosslink); in physics terms, the system relaxes when it dries.
I will give CuSO4 another go in the future as (i) it is odd that it is not working and (ii) the Piper recipe uses 4 times more dichromate, for which the fish will not thank me.

Thanks everyone for your help, Charles

 

[JKV]

I'm just discovering this thread, so I might be a little late. Anyway,my post responding to CTwist's initial post of this thread still might help somebody.
1- I never tried bromoil on a redevelopped print. Having paper undergoing a double bleach process might have an (negative) influence.
2 - Your Venn formula: what dilutions are you using? The formula is based on 10% solutions (except for the dichromate: 1%):
Solution 1 (Bleaching Bath)
Copper sulphate 10% solution 95 parts
Potassium bromide 10% solution 5 parts
Solution 2 (Tanning Bath)
Potassium bromide 10% solution 20 parts
Potassium bichromate 1% solution 10 parts
Water to make 100 parts
Bleach for 30 seconds past the disappearance of the image in Solution 1, then tan for 4 minutes in Solution 2.
Solution 1 can be used repeatedly, until bleaching times are too long.
Solution 2 should be mixed fresh for each use.
The bleached matrix must be refixed for 5 minutes, with continuous agitation, in a 10% plain hypo solution (sodium/ammonium thiosulfate), followed by a thorough wash. The fixed matrix will still show a slight brown or yellow-green image. This can be removed by a bath of 1% sulfuric acid, but you can ignore this step and leave the matrix as is.
After this, the print has to be thoroughly dried before being soaked and inked. Some state that more wet/dry cycles a matrix will go through, the more readily it will take the ink. I never tried this myself....
I hope this might help some of you
Jacques Kevers - Picto Benelux
http://www.picto.info/Etech.html

 

[M Carter]

Dry. (I don't know why the paper has to be crispy dry when you are only going to re-wet it , but there you are, its what you have to do!).

This has been called "super-drying" and while nobody seems to know technically what's going on, most bromoilists find a super-dried print inks better. It's believed that it causes better swelling of the emulsion when soaking.

I've had some success with Bromoil, and it's worked for me - in fact it's believed that drying, super drying, re-soaking, drying and super drying again, and then soaking for inking is effective - that several super-dry cycles make for better inking.

I also have the book "Bromoil: A Foundation Course" (by Derek Watkins, 2006) - while I've always mixed plain thiosulphate fixer for bromoil, the author states he sees no difference when using lford's rapid fix. He also shows Ilford MGWT matte as a suitable bromoil paper - I intend to test it after the holidays. I got decent bromoils from Ilford's non-warmtone multigrade but they didn't build up a lot of ink density - my take at the time was it seemed likely I could dial this in over time if I had to.

Foma's pre-gelatin change 123 was a spectacular bromoil paper; it was also a great lith printing paper so all the stock seems to have been bought up. The re-release (123 BO) was said to be designed for bromoil, but there's a very significant texture to the paper which looks too "contrived" for my tastes. Not sure if BO was a success enough that it's still in production, I'd check Freestyle's web site as they kind of championed that paper.

 

[NedL]

....
. He also shows Ilford MGWT matte as a suitable bromoil paper - I intend to test it after the holidays....

I'm very curious to know how it goes. Please let us know either way. Good luck with it!