Fomapan R

Michael_K · 2008-09-18T22:26:09+00:00

Ich habe heut nochmals einen Teststreifen entwickelt; diesmal habe ich die Bänder im destilierten Wasser angesetzt und bis auf die Wässerung nach dem Bleichb...

Michael_K

I developed another test strip today; this time I placed the strips in distilled water and, apart from the washing after the Bleach bath, I also used distilled water for the washings. During the intermediate exposure, I could still make out something on the film, but after the second development, the film was completely clear. I’m using a 150-watt bulb; perhaps I held it too close. I’m sure I’m making a silly mistake, but I just can’t figure out what it is. Please help. Thanks

orwograph

I’m sure I’m making a silly mistake, but I just can’t figure out what it is. Please help. Thanks

I don’t think so. That’s why bleaching with potassium permanganate is really only a stopgap solution. The problem is the curing or softening of the gelatin. Whilst bleaching with dichromate nicely cures (hardens) the emulsion during the process, it is softened in the permanganate bath. The emulsion always collapses during the second development stage. I won’t have chromates in my bathroom, so I started experimenting. In order: I’ve never used any Foma kit; it’s simply far too expensive for me (the forum admin will have to forgive me – it’s not his fault, after all). So I made my own. Here, then, is my ‘formula for success’ – may it enrich the world :angry:. I didn’t invent it myself, but cobbled it together from various recipes and tested it. Works flawlessly with the films I’ve tested: 1. Developer Variospeed W 1+4 or any other paper developer in a comparable dilution 11 mins at 22°C Washing 1 min 2. Stop bath 400 ml water 40 g potassium alum (potassium aluminium sulphate) 13.5 ml H₂SO₄ (37%) to make up 500 ml water 2 mins Washing for 1 min 3. Bleach bath 1 g KMnO₄ to 500 ml water 5 mins by eye (open the canister approx. 1 min after bleaching begins and then bleach until the silver staining on the film has disappeared) Washing for 1 min 4. Clarifying bath 500 ml water 5 g sodium disulphite 2 mins by eye, until the brown stain has disappeared. Washing, second exposure, a few minutes, no upper limit 5. Second development in the first developer 3 mins (The emulsion dissolves here, IF it dissolves!!) (If you feel like it, you can wash/wash again here, but I’ve never done that) Washing 1 min 6. Fixer 2 mins Washing: 10 mins Fixer bath: 5 drops of washing-up liquid / 0.5 l water. Dip briefly and then pour the rinsing solution over the film. Do not wipe off under any circumstances (the emulsion is soft despite the wetting agent)!!! Gentle drying without aids. Stuttgart tap water was used for all baths and washing. The critical points (in terms of layer separation) are the stop bath and the concentration of the permanganate. My earlier attempts with fresh bleach solution always led to the much-described disaster; the older (more inactive) the permanganate bath became, the better it went, but there was always some layer separation. So I reduced the concentration of the permanganate bath to 1g/500ml of water and also introduced the potassium alum bath. So, for the whole process, in addition to the paper developer and fixer, you need four further chemicals: sulphuric acid, potassium permanganate, sodium disulphite and potassium alum. The latter two are readily available at the chemist’s (perhaps they’re cheaper elsewhere too); for the former, you’ll have to get creative, as they aren’t readily sold off the shelf. However, there are mail-order suppliers of photographic chemicals that stock them; a quick Google search helps. Or you can get them from a trusted chemistry teacher, or strip your car battery, or or or :) The results of the reversal process have absolutely won me over. It all depends very much on the film used, though. For me, the Tasma FN64 was the absolute favourite; the Rollei Retro was also okay, but it was a bit flat, lacked a clear background and had significantly larger grain. I’d recommend the Tasma FN64 (actually a negative film with rather eccentric properties) to anyone interested in black-and-white slides in 35mm format, but unfortunately you can hardly buy it anywhere. I’ve never actually seen the Foma R. To sum up, if you want to or have to work with the Foma kit: you can certainly use the Foma chemicals and simply insert the Hüter bath at step 2 after the initial development. You can also weigh out the potassium permanganate (which is supposed to be packaged separately) to achieve the 2g/l concentration I recommend. No idea how much is in the Foma kit. Here’s a small selection of my results, both successful and less successful initial attempts: http://www.flickr.com/photos/8242862@N07/s...57607415955375/ I’d love to see an abstract of your results! Peter.

HaraldLeban

I notice that you are using a conventional developer for the ‘initial development’ stage. With the reversal process, however, you need to add a silver-forming agent (potassium/ammonium thiocyanate, rhodanide) to the initial developer, as well as potassium iodide, to keep the silver deposition that is initiated in check. (This is actually intended to clarify the highlights in the final positive.) As for the bleaching process, I would recommend carrying out the cross-linking process using chromium alum (potassium chromate) directly in the permanganate bleaching bath. Chromium alum is much more effective and simulates cross-linking in a similar way to chromate bleaching baths. As an alternative, a Bleach bath based on iron(III) salt would also be recommended, similar to the bleach-fix baths used in the colour process (but without fixing), e.g. iron(III) nitrate/sulphuric acid. Here is a link: http://www.markerink.org/WJM/HTML/hieslide.htm Good luck Harald

orwograph

Thanks a lot! I’m well aware about the potassium rhodanide – it’s in all the recipes – but I’ve always seen it as a ‘fine-tuning’ step, and at least with Russian films, it isn’t strictly necessary. Although you’re right, the highlights could be brought out a bit more. I’ll see if I can get hold of the stuff somewhere. Chromium alum is a good tip – do you have a recipe or details on quantities and timing? Regarding the iron(III) bleach bath: OK, I’m not a chemist, just a user with basic knowledge. I’m a bit surprised you’re suggesting that. I thought it wouldn’t work, because bleaching with, say, red blood salt produces re-exposable silver halide, meaning the entire emulsion would be exposed during the second exposure, which would result in a completely black slide. But OK, you’re talking about iron(III) nitrate here, which is something completely different, but the fact that you can make a bleach bath from it is completely new to me. At least all the DIY recipes I’ve come across so far are based either on dichromate or permanganate. Peter.

cfb_de

Hi Peter, "Potassium rhodanide" = potassium thiocyanate. This stuff is classified as harmful to health (so nothing out of the ordinary) and should be available from your local chemist if you specify what you’ll be using it for. Alternatively, you could try enquiring at the usual mail-order suppliers. Koehlerchemie and omikron spring to mind. genec.de would also be worth a try, if Mrs Neubauer is still running the business following her husband’s death. Actually, that (Neubauer) is the first port of call for enquiries. I just don’t know for sure, as I usually order laboratory chemicals to cover a five-year supply. As for the residue of the reverse process, I’ll keep quiet – I’ve still got plenty of chromium(VI) oxide to hand. And I can make dichromates from that myself. My privilege as a chemist :-) (Nope, I’m not revealing how it’s done. Certainly not to people with no laboratory experience. And everyone else has no questions on the matter. For the inexperienced, my refusal to reveal this serves their own safety and my long-term survival.) Best regards, Franz

orwograph

I won’t go into the residue of the reverse process; I still have plenty of chromium(VI) oxide left. And I can make dichromates from it myself.

But there’s no need for them at all, because potassium permanganate works perfectly well if you work carefully. The scaremongering (that it’s unreliable, etc.) isn’t justified, in my opinion. Peter.

ChristianKolinski

I notice that you are using a conventional developer for the ‘primary development’ stage. With the reversal process, however, you need to add a silver-forming agent (potassium/ammonium thiocyanate, rhodanide) to the primary developer, as well as potassium iodide to control the silver deposition that is initiated in this way. (The whole process is actually intended to clarify the highlights in the final positive.)

Not strictly necessary – the original Foma kit also dispenses with such additives and uses the same solution for both primary and secondary development. I personally had hardly any problems bleaching Fomapan with permanganate; the old Super8 Svema proved to be more fussy, but could ultimately be persuaded to cooperate with a slightly diluted Bleach bath and the use of slightly acidic intermediate baths. Apparently, the sharp pH changes also seem to take their toll on the emulsion; you could actually watch the emulsion ‘tear’ as the second developer was poured in. Regards, Christian

orwograph

Not necessarily – the original Foma kit also does without such additives and uses the same solution for both the first and second development stages.

However, using the same developer doesn’t prove that there’s no rhodanide in it. Or are you absolutely certain?

Apparently, the sharp pH changes also seem to be taking their toll on the emulsion; you could actually see the emulsion ‘tearing’ as the second developer was added.

But that doesn’t necessarily mean the pH value is to blame. Of course, the emulsion always breaks down at exactly this point, namely as soon as the film comes into contact with the second developer. It’s also possible, however, that it’s not the pH value but one of the substances in the second developer that’s destroying the gelatin. Just for fun, you could try holding the film in a calibrated base instead of the second developer... It’s striking that the separation doesn’t happen if everything else stays the same, but only the potassium permanganate content in the Bleach bath decreases. In fact, the permanganate does something to the gelatin that isn’t a problem in the intermediate baths (the gelatin always remains nice and firm), but leads to its demise the moment it is immersed in the secondary developer. But it doesn’t really matter, as the problem can be solved quite easily. Peter.

HaraldLeban

Chromalaun is a good suggestion – do you have a recipe or details on quantities and timing? Try 50g/l – that should be enough Harald

ChristianKolinski

Not necessarily – the original Foma kit also does without such additives and uses the same solution for both the first and second development stages.
However, using the same developer does not prove that there is no rhodanide in it. Or are you absolutely certain?

1. It would be an unusual addition for a universal black-and-white film developer 2. It isn’t listed in the MSDS 3. According to Foma, it isn’t in there...

...which still doesn’t mean the pH value is to blame. Sure, the emulsion always breaks down at exactly this point, namely as soon as the film comes into contact with the secondary developer. But it’s also possible that it’s not the pH value, but one of the substances in the secondary developer that’s destroying the gelatin. Just for fun, you could try putting the film in a calibrated base instead of the secondary developer...

It wasn’t calibrated, but a weak sodium hydroxide solution has the same effect...

But it doesn’t really matter, as the problem can be solved quite easily.

Exactly. You just use dichromate... *duck* :angry: Christian

HaraldLeban

[But that doesn’t necessarily mean the pH level is to blame. Sure, the emulsion always breaks down at exactly that point as soon as the film comes into contact with the secondary developer. M... ] ....In pigment printing, glycerine and sugar are added to the colour gelatine to keep it flexible, particularly during the transfer of the image..... Perhaps the problem of delamination could be kept in check by adding glycerine, ethylene glycol or sugar to the secondary developer (though the concentration would need to be at least 20–30%) and thus carrying out the rest of the process unchanged. In general, the reverse development process, with its extreme pH fluctuations, is a real ordeal for the gelatin emulsion. My recommendation is always to include sufficient washing stages to harmoniously balance out the pH and salt fluctuations, and then possibly use a milder secondary developer (film developer). From my experience with reversing lith films, I know that overly hardened thin-layer emulsions are also very prone to delamination if they are processed too aggressively. Good luck Harald

Gucker

First of all, a big thank you to the forum administrator for leaving the posts online indefinitely. Yesterday I was also faced with clear positives (Ilford FP4) and couldn’t explain it at first, as I’ve been doing reversal processing for quite some time – including a few times with potassium permanganate. Without this forum post, I wouldn’t have been able to identify the emulsion detachment straight away; today I worked with half the concentrations – as suggested – (and also with gentler agitation during bleaching) and lo and behold: everything as it should be; incidentally, I didn’t use the hardener before bleaching. In any case, it certainly doesn’t work as Ilford describes it at: http://www.ilfordphoto.com/Webfiles/20061291034093.pdf, at least not if you agitate continuously for 5 minutes during bleaching.