Yet another Chlorohydroquinone thread, but with synthesis

[Lachlan Young]

So is resorcinol a thing you can just add to a developer to prevent stain or is it particular about the conditions? It seems there is one hobby friendly source for resorcinol.

Resorcinol is the third of the HQ isomers - for the large part it's not regarded as a 'useful' photochemical in the amateur photochemistry world, but there have been some interesting hints over the years about what Kodak (and others) were using it for in research.

Very interesting about the PEG. So basically PEG slows access of the developer to the emulsion, but by slowing that access can make it so that it all kind of happens in a uniform way, thus acting as either a restrainer or accelerator... I think I'm understanding that. Swell dynamics is definitely something I do not have a full grasp on

I'm making a conjecture based on your observations of using PEG in experimental lith formulae - I don't think it'll do much to slow access with 'conventional' developers. Given the chain-reaction nature of lith development & the near-exhaustion state that lith developers are used in, it's simply making me wonder if it somehow is affecting the formation/ inductance/ diffusion time of the HQ derivative that does the actual developing - or that at a particular molecular weight it somehow prevents the uptake of HQ, but allows the ready uptake of HQMS/ semiquinones.

It really is rather odd that Ilford RC papers work, but most of the FB papers don't. The big thing I don't understand is how these papers consistently work without fail when bleaching and doing second pass lith. I can't get a handle. I've ever tried bleaching before exposure before and this did not seem to magically make the paper first pass lithable. That was also a few years ago though so I can't remember much of the details.

I think there may be something that's cleared in the fixer as well - MGWT FB (brighteners but not heavily ballasted, so they can be washed out) is first pass lithable, but with most of the density only kicking in as it touches the fixer - suggesting that whatever the fixer's initial reactions are (before it even gets to significantly reacting with the halides) may be having an impact.

in a developer+film combination known to cause dichroic fog.

That might be quite difficult, given that a number of modern emulsions are intended to give maximised sharpness/ granularity performance in quite solvent developers, thus are likely to have a fair amount of anti-stain agents etc incorporated.

 

[Lachlan Young]

In the context of modern/contemporary emulsions, if it were as simple as adding something such as chlororesorcinol to a developer, presumably someone would have done this with TMax developer to prevent the potential sheet film dichroic fog issues which historically necessitated the use of TMax RS under certain conditions. Probably a moot point now as the latest version of TMax developer apparently works with sheet film.

Going by the implications in the older Tmax developer data sheets, it would appear that the issues were from deep tank and/ or tray usage.

 

[MattKing]

Probably a moot point now as the latest version of TMax developer apparently works with sheet film.

Can you point me to the source for this?
I ask, because of efforts to get T-Max RS back in smaller quantities .

 

[MattKing]

It's not "official", just prelim test results by John Sexton/Anne Larsen discussed in John's newsletter in which he talked about the discontinuation of TMax RS, the history of the dichroic fog issue with TMax dev/sheet film etc.:

http://www.johnsexton.com/newsletter07-2021.html#anchor05

Thanks for that Michael.
The information about T-Max RS that I have indicates that as of December last year the 25 litre size of T-Max RS was still being produced, and that they were looking at the feasibility of at least one smaller size.
John Sexton's newsletter is more recent, and I would expect him to be correct, but it would be great if he was mistaken on that.

 

[Lachlan Young]

It looks likely that the dichroic fog problem with certain films & T-Max developer was resolved (and clearly thoroughly unpublicised) as emulsions moved to B-38.

 

[Tom Kershaw]

It's not "official", just prelim test results by John Sexton/Anne Larsen discussed in John's newsletter in which he talked about the discontinuation of TMax RS, the history of the dichroic fog issue with TMax dev/sheet film etc.:

Michael,
Thanks for the reminder of John Sexton's newsletter, I seem to have come off the list and should re-subscribe.

Tom

 

[Lachlan Young]

Seems like an odd problem to have had to begin with and a strange explanation for it. If the move to B-38 did actually help in full or in part it would certainly be good news for people who were accustomed to using RS.

Bob Shanebrook might be the person to ask.

 

[grainyvision]

I agree that chlororesorcinol is the most likely antistain agent in Microdol-X. More broadly, US3161513 was filed by Henn a few months following that first "nonstaining developer" patent and details the use of 2,4-dihydroxybenzophenone. So, jut between those two patents, we have resorcinol, its chloro- derivative, and the substituted benzophenone. All three are commercially available, though, granted, resorcinol is likely the easiest to obtain by the hobbyist. I'm not sure if either would be suitable as a component in developers for color film, however. It is certainly worth trying. Dichroic fog is a non-issue in most other conditions, as others have noted, due to improved emulsion technology.

In the HC-110 patent, reference is made to an article (PSA Journal, Vol. 14, No. 4 (1948), pages 201-209) discussing dichroic fog and preventive agents. If anyone has PSA membership, that article would be greatly appreciated. I wonder if the mechanism(s) whereby these compounds prevent stain formation is known. If that knowledge is available, we could potentially predict other compounds that would be effective. Additionally, povidone was used in HC-110, according to the patent, because prior known antistain agents failed in developers containing amines. However, nothing suggests that it wouldn't be functional in a sulfite-solvent fine-grain developer of the D-23/25 type or in Ashley's attempted reversal developer for ECP film. Based on the patent, it might be active in fairly low concentrations (250mg/L concentrate equals about 8mg/L of working strength Dilution B). Eyedrops often use PVP as the active lubricant/hydration enhancer. A quick search brings up Bausch+Lomb Soothe, Long Lasting eye drops, containing 2% povidone, and a minimal amount of inactive ingredients (borates, EDTA, antimicrobials). A 15 ml bottle is thus equivalent to the amount of PVP in a liter of HC110. I'd suggest buying a bottle and trialing it in 0.5 mL increments in a developer+film combination known to cause dichroic fog.

Re CQ, superadditivity, low-pH HQ developers, I don't think hydroquinone and chlorohydroquinone would be superadditive, at least not in the traditional concept of the theory. The chlorine substitution shouldn't make the molecule any more strongly adhering to AgX, indeed, the electronegative Cl might increase electrostatic repulsion at the boundary. At the same time, it stabilizes the semiquinone which explains its increased activity compared to HQ (behaving more like pyrogallol but without the increased susceptibility to oxidation). I don't know much about the behavior of HQ at pH lower than 10. Do you use a pH meter (and what kid) or test strips to check the pH? What is the purity of your HQ and can you verify that there isn't something else going on to contribute to the developer's activity at low pH?

Since povidone is relatively simple to purchase I'll likely try that first. Resorcinol is available but looks rather expensive and again only one hobby friendly source. This is for use with a color negative film, but reversal process to specifically handle dichroic fog that I believe is happening in the first developer. It's kind of hard to confirm, but all indications seem to point to this being dichroic fog. There is an irridescent sheen and the color of the film looks red by transmitted light and grey-green by reflected, and even with the color developer made extremely over active, it behaves like there is just no silver halide left to develop if I'm naive with the first developer formula. In regular E-6 process it gives 100% clear film with no color development. due to this effect (and yea CD-4 is bad for CD-2 film, but I'm using proper CD-2 color developer now and still get the same effect if I'm not careful)

I use pH test strips (4 color panel ones) for judging pH, so while it's not super accurate I can be pretty certain at least within a tolerance of 0.5, especially in the 8-11 range. In one trial I had ran out of test strips and so I used a bicarb + carbonate buffer targeted at 9.3, which worked albeit slowly and not active enough for a print developer (no proper black). I have a new formula I'm planning now which directly uses the 58-D formula with this hydroquinone substitution, but replacing the plain carbonate alkali with a bicarb+carbonate buffer system aimed at pH 9.5 with a molarity of 0.8M. I've long believed that most developing agents work at lower pH than people expect. I've seen ascorbic acid produce images at 11.5, whereas most references say it requires 12.5 or higher.

One thing with the trial runs of this HQ only kind of developer is the image develops in an extremely linear way, resulting in some small loss of contrast and a major loss of speed depending on pH and other factors. It reminds me of lith printing but without the chaos. I believe the relatively small amount of sulfite and over surplus of hydroquinone is what is allowing this developer to be active enough to get proper black tones. Basically it's somehow getting enough radical action to create an image with proper black tones, but it's not "infectious.. While this is not an infectious development style lith developer, it resembles one in many ways. Also PEG-3350 does not function as an accelerant for this developer. Adding it prevented black tones from occurring and slowed down overall activity