Large format direct positives B&W

[George Collier]

Greetings - I have a friend doing very creative work in a graduate program, and among other things, is using an 8x10 view camera to shoot Ektachrome transparencies, a pricey endeavor. He would like to do some with a B&W film / process.
In his search for this, he has seen some info on the Ilford web site, including info for self mixing, including the use of sulfuric acid, which has concerned him a bit, due to potential handling issues.
I remember the old Kodak direct positive kit, back in the 70's used with Panatomic-X, as I remember, which I don't think is any longer available.
Any suggestions for him? He is quite energetic and smart, so some level of work and difficulty will not be an issue (he processes his Ektachrome himself).

 

[thinkbrown]

https://www.photrio.com/forum/resou...ach-—-hydrogen-peroxide-edta-citric-acid.448/ this might be a good place to start if you want to avoid sulfuric acid. I'm currently experimenting and trying to get the process working for myself

 

[koraks]

[...]including the use of sulfuric acid, which has concerned him a bit, due to potential handling issues.
[...]
Any suggestions for him? He is quite energetic and smart, so some level of work and difficulty will not be an issue (he processes his Ektachrome himself).

So he can learn to safely handle the sulfuric acid; no problem there at all.

Does he want to do transparencies or direct positive prints on paper? Both are possible. I'd recommend starting with the latter to get a grip on the overall process. Reversal processing isn't too difficult in principle; the trick is to control contrast. Lots of trial & error involved. The chemical steps aren't too complicated. Risk of harm is really, really minimal if he observes some basic safety & sensibility measures.

 

[Craig]

Kodak used to make direct duplicating film, SO-339 that you can make a direct positive with, or you can reversal process a negative film.

There is a fair bit in the resources section of this website. One example: https://www.photrio.com/forum/resou...ormulas-and-workflow-by-philippe-georges.450/

Kodak version: https://www.photrio.com/forum/resources/kodak-b-w-reversal-process-with-fogging-redeveloper.356/

 

[Raghu Kuvempunagar]

In his search for this, he has seen some info on the Ilford web site, including info for self mixing, including the use of sulfuric acid, which has concerned him a bit, due to potential handling issues.

Adox Scala Reversal Kit, Foma Reversal Kit, and Bellini Reversal Kit can be looked at.

 

[blee1996]

I have not tried it myself, but from my understanding you can use Ilford FP4+, Delta 100, Rollei Ortho 25 (all available in 8x10 sheet size) for direct positive. I would also start with a reversal kit to get a feel for the process, before mixing own chemicals.

 

[George Collier]

Thanks for the comments and suggestions. He wants a direct positive (transparency) result from shooting film, whether the film is intended for Positive or negative. Any path to a final B&W positive transparency.

 

[Raghu Kuvempunagar]

Astrum sells a direct positive film. Check with @MCB18 who might have more info/experiences to share.

 

[MCB18]

Astrum sells a direct positive film. Check with @MCB18 who might have more info/experiences to share.

Hi! Not in LF, but in 35mm. Honestly I’m a bit underwhelmed by it, it’s a cool film for sure but my god the slides are super thin…

I do have a direct positive film from Kodak, it’s film 2422 and it comes in giant 9.5” rolls. And it works really well! The downside is that it’s SLOWW, as in, the best results I’ve seen thus far come from @gezak22 who got a speed of 0.4 ISO after processing it in Rodinol 1+25 for 30 minutes.

I’m absolutely willing to cut some of this film into 8x10 (when I have a spare few hours over the weekend) for your friend if he wants some, just let me know!

 

[MCB18]

Oh, here’s an example of the film. Direct negative enlargement, turned out very well.

 

[Ivo Stunga]

No special film needed to pull this off - it's the processing that turns BW film into BW slide. I do however recommend looking for a PET base for extra clear/crispy slides.

 

[Lachlan Young]

Standard issue B&W reversal processing on 8x10 sheet film will do the job. All the relevant materials are on PET clear base, so you'll get good highlights.

 

[George Collier]

MCB18 and​

Lachlan Young​

Thank you for the responses. Can you say more about the direct processes (chems, etc) or point to where info is?

 

[MCB18]

MCB18 and​

Lachlan Young​

Thank you for the responses. Can you say more about the direct processes (chems, etc) or point to where info is?

Well for 2422, this is probably the best place to find info:
https://www.photrio.com/forum/threads/the-kodak-2422-direct-duplication-film-thread.212323/

 

[Craig]

MCB18 and​

Lachlan Young​

Thank you for the responses. Can you say more about the direct processes (chems, etc) or point to where info is?

All you need is here: https://www.ilfordphoto.com/reversal-processing/

 

[MCB18]

All you need is here: https://www.ilfordphoto.com/reversal-processing/

I believe that he has already discounted this method due to not wanting to handle sulfuric acid.

 

[Lachlan Young]

MCB18 and​

Lachlan Young​

Thank you for the responses. Can you say more about the direct processes (chems, etc) or point to where info is?

Start with the Foma or Adox kits, however handling Sulphuric Acid is fine if done in an appropriate environment wearing appropriate PPE. The acidified permanganate bleach is preferable to the old dichromate bleach, but do not use first developers containing potassium thiocyanate with permanganate bleaches.

 

[koraks]

The acidified permanganate bleach is preferable to the old dichromate bleach

From an environmental and healthy & safety perspective, yes. From a technical perspective, not per se. I think many people (including myself) have experienced that dichromate bleaches tend to be a little more robust, stable, less likely to damage the film and overall easier to use. But...hexavalent chromium. Someone hesitant to handle sulfuric acid surely would balk at using this.

I believe that he has already discounted this method due to not wanting to handle sulfuric acid.

In this case, painting oneself into a corner really is a choice, and one I already recommended steering clear of.

 

[Ivo Stunga]

Acids aren't that dangerous with simple acid-safe gloves and a pair of cheap safety glasses. And you can make a larger volume of working solution to reduce one's exposure to concentrates. At least you can see where the spillage is.

 

[isaac7]

From an environmental and healthy & safety perspective, yes. From a technical perspective, not per se. I think many people (including myself) have experienced that dichromate bleaches tend to be a little more robust, stable, less likely to damage the film and overall easier to use. But...hexavalent chromium. Someone hesitant to handle sulfuric acid surely would balk at using this.


In this case, painting oneself into a corner really is a choice, and one I already recommended steering clear of.

Photo Engineer felt that dichromates were safer than permanganate. He felt that the risks of dichromates were easily mitigated while he worried about how strong an oxidizer permanganate is. He was also very worried about accidental combinations with other common darkroom materials. He didn’t mind having dichromate in his house but said he wouldn’t have permanganate in it.

Safety is a difficult thing to quantify. Clearly all three of the chemicals being discussed need to be handled with care. I haven’t tried B&W reversal processing myself but I am interested. Reading the different discussions here makes it seem like good results are certainly possible but it does take quite a bit of testing to nail the process as compared to negative development. If (when?) I try my hand at it I will most likely do it with the hydrogen peroxide/EDTA bleach that has been discussed.

A Better Black and White Reversal Bleach with Hydrogen Peroxide

In a previous post, I described how to develop your own black and white slides using a simple bleach based on hydrogen peroxide and vinegar. This post is about an improved bleach that has a number of advantages over that one. There are a lot of patents out there from the 1970s through the late...

imager.ie

If I couldn‘t get that to work I’d just go the dichromate route with a reducing agent like citric acid to least make the waste less toxic.

 

[gezak22]

Kodak 2422 will produce a positive in Rodinal. You can find a sample image here, and a minimal (1/3 of a roll of 120 offer very little room for a full curve) film speed test curve is here. In short, Rodinal 1+25 for 30 minutes gives a film speed of ~ISO 0.14.

Edit: I work in the semiconductor industry, and handle sulfuric acid regularly, but no way am I using that stuff at home. Safe handling is just one concern, safe disposal another.

 

[Donald Qualls]

dichromate route with a reducing agent like citric acid to least make the waste less toxic.

I would note that sodium sulfite does a very good job of converting hexavalent chromium ion to the far less hazardous trivalent form (in solution, that's visible as a change from orange to green). When I've done dichromate reversal, I just poured the sulfite clearing bath into the bleach when I was done working, and disposed of the combined solution (about a pint) down the drain into city water treatment.

I'd be more concerned about dropping this into a septic system, but that's due to ignorance rather than any knowledge of whether chromate or low concentration sulfuric acid does any harm to septic bacteria.

 

[blee1996]

I looked at Adox's B&W reversal kit information, and it seems not containing any of the above hazardous chemicals in its bleach. Just curious if Adox has a secret formula that is much safer?

 

[koraks]

I'd be more concerned about dropping this into a septic system, but that's due to ignorance rather than any knowledge of whether chromate or low concentration sulfuric acid does any harm to septic bacteria.

I wouldn't expect this to be a problem; what you'd be dumping into the tank after reducing the dichromate would be a small amount of Cr(III), which probably is inert to most bacteria. Of course, it will generally be considered bad practice in general terms to discard heavy metals into the environment. The question ultimately is also how strictly one wants to adhere to a certain ethic.

 

[Donald Qualls]

The question ultimately is also how strictly one wants to adhere to a certain ethic.

If we all adhered to the level where a few tens of milligrams of chromate were a big deal, I doubt we'd be using silver-based photographic materials, either. Given reversal isn't something I plan to do a lot of, I'm more concerned about the one-time effect than the accumulation in the septic tank being an environmental hazard.