Adjusting pH of Ilford Rapid Fixer or Hypo based Fixers for Color

[laingsoft]

Because of this pandemic, all of my local photo shops can't really get any chemicals in, and because of where I live, ordering them through the mail is also difficult and expensive.

I've managed to get myself everything that I need to make some c41 dev, but I'm missing ammonium thiosulfate for the fixer. Judging by the reading I've done here, the fixing times with color film in hypo is insanely long as the sodium ion has trouble diffusing through the gelatin, so I don't know if that is going to be an option. I do however have some Ilford rapid, which I read will work, however may cause the dyes to go transparent. I measured the pH of the ilford fixer at 4:1 and it was iirc ~4ish Can I use some sodium hydroxide/carbonate/borax/whatever base to adjust the pH back up to 6.1 ala flexicolor? I've got a pH meter so measuring shouldn't be an issue.

 

[Donald Qualls]

You'll also get incomplete fixing with sodium thiosulfate as opposed to an ammonium thiosulfate fixer. Using a dual fixing bath helps some (lets the first fixer do the heavy lifting, while the second finishes up), but even so, for tabular grain (which is apparently all C-41 films now) it's still possible to get incomplete fixing.

What I'd suggest, rather than try to neutralize or alkalize an existing acid fixer, is to make your homemade fixer into a rapid fixer by adding ammonium chloride. I've read opinions that this doesn't work, but it's exactly what Cinestill does with their Df96 dry package -- the fixer component comes as the very recognizable hypo crystals, and something else in the mix makes the fixer "rapid" by adding the ammonium ion. This should give a nearly neutral fixer (in Df96 it works at the developer's alkaline pH).

 

[laingsoft]

Df96 is a black and white PQ monobath though, it likely doesn't need ammonium, as most of the monobath formulas I've seen have used pure hypo or hypo and some other mercapto-compound.

I suppose doing a replacement replacement reaction with NH4Cl would make sense. Should be 1mol hypo to 2 mol of ammonium chloride, I doubt the sodium or chloride are going to make a difference for the fixer. It looks like I can order ammonium chloride on amazon, so maybe I'll give that a go.

 

[Donald Qualls]

Df96 is a black and white PQ monobath though, it likely doesn't need ammonium, as most of the monobath formulas I've seen have used pure hypo or hypo and some other mercapto-compound.

The process time for Df96 says rapid fixer to me -- 3 minutes at 80F for common films, and full fixing (even pink dye removal for tabular grain) with double time.

 

[koraks]

Can I use some sodium hydroxide/carbonate/borax/whatever base to adjust the pH back up to 6.1 ala flexicolor?

Yes, that should work just fine.

 

[Murray Kelly]

I add ammonium sulfate from the garden shop. Not as fast but it does the job.

 

[Lachlan Young]

The process time for Df96 says rapid fixer to me -- 3 minutes at 80F for common films, and full fixing (even pink dye removal for tabular grain) with double time.

There's a decent likelihood that that product is based on your recipe from 2004...

EDIT:
The MSDS for DF96 claims sodium thiosulfate is used

 

[Donald Qualls]

Oh, definitely, sodium thiosulfate is used; I've mixed Df96 from the dry package (cheaper, and cheaper and faster to ship, than the liquid), and the sodium thiosulfate crystals are unmistakeable. Could still be a rapid fixer in the end product, though -- a quantity of ammonium chloride too small to be required on the SDS would do the job, and that could even be in the other packet (with the developer). Fixing in three minutes is the deal.

I don't know how many generations of "make it mine" there are between, but I think the modern resurgence of monobaths and monobath-based products (like New55) is at least partly based on my 2004 experiments. In this case, pretty loosely based, I'd say; I started with HC-110 and Ilford Rapid Fixer, added ammonium hydroxide to offset the acidity of the fixer, and got lucky with it working on the first try. The R-1 monobath that New55 folks sold was, I've heard, exactly my formula, right down to the ammonia smell.

My original experiments, however, used 6 minutes, even with rapid fixer on cubic grain Tri-X. Might well have been fully fixed sooner, but I was used to giving three in full strength, and my fixer was about half strength or a little less.

Further, it's pretty well accepted that it's almost impossible to get full fixing with tabular grain films in standard hypo fixer as a single bath (works much better with two-bath); I don't think Cinestill would specify a monobath with the expectation of using it for all B&W film stocks, without making the fixer component capable of fixing all B&W film stocks.

 

[Lachlan Young]

Further, it's pretty well accepted that it's almost impossible to get full fixing with tabular grain films in standard hypo fixer as a single bath (works much better with two-bath); I don't think Cinestill would specify a monobath with the expectation of using it for all B&W film stocks, without making the fixer component capable of fixing all B&W film stocks.

I'd like to hope that they know that ammonium thiosulfate is necessary for modern BW & colour films, but they sell a powder C-41 kit (which can only be sodium thiosulfate), so I'm not convinced of their chemical knowledge.

 

[Donald Qualls]

Just as with the dry Df96 kit, in-solution addition of an ammonium salt will provide the necessary conditions for rapid fixing. C-41 films, like tabular grain, cannot be fully fixed in reasonable time by a single-bath fixer with only sodium thiosulfate as the fixing agent. The rehalogenated developed silver is a separate question, but the undeveloped halide in most if not all modern C-41 film stocks is tabular (most likely even formate doped, as that was one of the last developments before the film market crashed and Kodak, at least -- the patent holders -- jumped on it for their cine stocks and as I recall trickled it down to their still films as well).

 

[koraks]

a powder C-41 kit (which can only be sodium thiosulfate)

Not necessarily. Ammonium thiosulfate also comes in dry form. It tends to lump a bit, but perhaps they add an anti caking agent.

 

[Donald Qualls]

Not necessarily. Ammonium thiosulfate also comes in dry form. It tends to lump a bit, but perhaps they add an anti caking agent.

I had understood it was so hygroscopic as to be difficult to ship and mix as powder, because it absorbs water out of the air so rapidly it doesn't just cake, but liquefies in transit, and you can't be sure what water content it has (I've only seen it offered as 60% solution).

 

[koraks]

I've had a kilo or so sitting around for going on 2 years now; looks and smells pretty much the same as the day I got it.

 

[Donald Qualls]

Okay, I'd never seen this offered in dry form, but apparently I can buy it on Amazon in 1mm granules, 98% pure -- for $96/kg. Even with the cost of shipping water, it's cheaper as 60% solution (which costs the same as C-41 fixer, if not a bit more).

 

[laingsoft]

Update for posterity:

Took my 1L of 1:4 ilford rapid that I had used previously, added 54ml of Ferric Ammonium EDTA. Then I made up some hydroxide solution and adjusted the pH to 6.5. Images look good. I used some orwo black and white film, developed it in daylight to complete black, then used the blix on it, fully cleared in about 4 minutes. Developed a roll of expired kodak gold 200 and blixed for 16 minutes.

My understanding is that if you were to use a fresh batch of fixer, you would need to add a small amount of KI, I think I didn't need to add it to my blix because it was already used, and the silver complexes in the fixer would behave in a similar manner as the iodide complexes that KI would form in fresh fixer.

As it turns out, I had actually previously exposed that roll before, so I ended up with some cool double exposures. Nonetheless, here is a raw, unedited file. This was a relatively long exposure taken during a rainstorm.

I take no responsibility if you do this and it turns out to not be archival, or you get weird color shifts. It seems like it's worked for me.

 

[laingsoft]

Another, non-double exposed photo from the same roll.

 

[Donald Qualls]

@laingsoft I see nothing to complain about with those images -- and the rain one with the trees double exposed looks really cool.

If you were going to make this on any sort of regular basis, it's almost certainly cheaper to buy C-41 Fixer Replenisher than Ilford Rapid Fixer (aside the fact that you have to buy enough of the C-41 chemical to make several gallons from the concentrate, where Ilford will sell you a small enough bottle to make a few liters). C-41 fixer is already alkaline, so no handling sodium hydroxide. If I were doing that, I'd most likely make up the bleach and fixer as separate baths, like I did when I first did my own C-41 (I was then able to easily and semi-locally buy the Flexicolor chemicals). Both chemicals last better when they're not fighting with each other.

BTW, where do you source ferric ammonium EDTA?

 

[laingsoft]

Right, blixes are not going to give you the best possible results, seperate baths will always be better. All of this is because I've been on a waitlist for cinestill kit for 5 months with my local shop.

I sourced the ferric ammonium edta from alibaba, I found a supplier that can send me basically anything I ask, but usually the minimum order is 500g. So far I've gotten hydroquinone, hydroxylamine sulfate, cd-4, ferric ammonium edta, titanium dioxide and intercalated graphite from him, the prices are usually pretty reasonable, but shipping isn't cheap.

I am someone that plays with chemistry quite a bit, so hazardous chems and workup don't bother me much as I have the equipment to deal with it.

 

[Donald Qualls]

Nice. I've been interested in mixing my own C-41/E-6 bleach, and the EDTA is hard to find unless it's the sodium salt. I've got a 2-bath C-41 developer formula that I've used before (and can probably convert to CD-3 for E-6), and C-41 fixer is easy (any non-acid rapid fixer will work), but ferricyanide rehalogenating bleach is really slow.