Presoak pH - add some sulfite?

[justpete]

Using distilled water with a measured pH of 5.5 might not be the best way to presoak. Maybe. Avoiding bath A agitation with a divided developer seems to yield the least artifacts so maybe the pH of a presoak needs to be made alkaline to swell the gelatin enough to more thoroughly saturate the emulsion? Maybe a bit of sodium sulfite would help? Just a thought. Am I out in the weeds on this?

 

[Ian Grant]

A pH of 5.5 is only very mildly acidic and due to CO2 absorption, so not really relevant.

Any use of an alkaline pre-soak. and certainly one that would swell the gelatin, would effectively make the use of a 2 bath divided developer pointless by encouraging development at the first stage.

Ian

 

[Tom Hoskinson]

Using distilled water with a measured pH of 5.5 might not be the best way to presoak. Maybe. Avoiding bath A agitation with a divided developer seems to yield the least artifacts so maybe the pH of a presoak needs to be made alkaline to swell the gelatin enough to more thoroughly saturate the emulsion? Maybe a bit of sodium sulfite would help? Just a thought. Am I out in the weeds on this?

.

Seems to me that a presoak in an alkaline bath is somewhat like a presoak in the B solution of your split developer. Not a good idea IMHO.

Good quality Distilled and Deionized water should be pH Neutral (not 5.5). I presoak in tempered semiconductor grade 18 megaohm Deionized Water (it's what I get from the monitored DIW filter chain in my Lab).

 

[justpete]

Yes, an alkaline presoak wouldn't be wise with a divided developer but I thought it might be a slight help with non-divided developers. I know the cause of the slightly acidic pH and that there's nothing I can do about it having bought the distilled water at the store. I don't have access to a DI water plant (wish that I did of course) but I don't think water is naturally neurtral given its polar property although its natural pH isn't as low as 5.5, typically, without time to absorb CO2 from the air.

And I wasn't thinking of getting to much of an alkaline pH, just above 7. More of a way to overcome the slight acidic nature of the water I've chosen to use than anything else. Then again I might be fighting a problem that's more related to how the film is dried in forced air and am chasing my tail over the whole issue. Good thing this is a relaxing hobby...

 

[Tom Hoskinson]

Yes, an alkaline presoak wouldn't be wise with a divided developer but I thought it might be a slight help with non-divided developers.

IMO, No help and most likely, a hindrance - certainly, another development variable you would then need to control.

 

[justpete]

IMO, No help and most likely, a hindrance - certainly, another development variable you would then need to control.

Thanks very much, I'll bypass this then and keep focusing on care in agitation, fill rate, fill percentage, etc.

 

[pgomena]

I would think a well-buffered commercial film developer would solve your water problem. I'm not so sure about two-bath home brews. Perhaps on of the more chemically knowledgeable APUG members can give you a better opinion.

Peter Gomena

 

[Trask]

OK, you'll think I'm nuts maybe, but I was thinking of a pre-soak and way to eliminate the halation layer, so I thought, when do I daily use a product that's a little sharp to get rid of unwanted stuff? So I diluted some Listerine Mint mouthwash 1:100 and did a pre-soak. Well, that seemed to take care of the halation layer in some Bergger film I tried, and the pictures were unaffected. No, I haven't done a controlled experiment to find out if a plain water soak would have done the same job. But my work area had a nice minty smell, and the negatives were fine. YMMV!

 

[Paul Verizzo]

Are you sure it's 5.5? That's the first thing I would question. Most of us don't have accurate pH testers; I have the old pHydrion papers. Sometimes it's hard to make the color differentiation.

I would talk to the bottled water company and ask for their thoughts. They might find pH 5.5 incredible or normal, who knows?

And why bother? I've never used a pre-soak and I'll wager have never suffered a problem. You definitely do not want to pre-soak for a two bath developer. It just pre-displaces what should be actual developer in Bath A.

 

[Photo Engineer]

There is a long thread on this about a month old. Most distilled water is pH 5.5 due to one of two factors. 1. the water absorbs CO2 from the air and 2. the stills are kept clean by washing the coils with acid to remove scale. Either way the water is more acidic than you might (or I might) expect.

Most tap water is about pH 6.5 - 8. Some cities add alkali to prevent corrosion.

Do not add alkali to the prewash though.

PE

 

[justpete]

Are you sure it's 5.5? That's the first thing I would question. Most of us don't have accurate pH testers; I have the old pHydrion papers. Sometimes it's hard to make the color differentiation.

I would talk to the bottled water company and ask for their thoughts. They might find pH 5.5 incredible or normal, who knows?

And why bother? I've never used a pre-soak and I'll wager have never suffered a problem. You definitely do not want to pre-soak for a two bath developer. It just pre-displaces what should be actual developer in Bath A.

Yes, I'm sure it's 5.5 or thereabouts. I have the 15 roll pHydrion set at the moment, it was less expensive than a meter for the time being and seems to be pretty accurate if used carefully (pipetted sample to watch glass and color comparison done under bright enough white illumination). And this is the pH the bottled distilled water's been every time I've tested it for last few months. Tap water on the other hand's gone from about the same to about 6.5 or so since the height of summer as the amount of chlorine's been decreased (I think).

I'm having some problems with development uniformity using non-divided developers the cause of which have been difficult to pinpoint. Earlier divided development test films show no such uniformity issues. However last night testing another eight rolls in divided D-76 the uniformity wasn't any better than film dev'ed in non-divided developers earlier in the weekend.

Prior to the second test with divided developer I thought maybe the alkaline nature of the bath A had something to do with gelatin swelling and possibly a more uniform absorption of solution. Apparently this isn't a good thing and after further research it would appear a presoak isn't necessary or even recommended for a number of perfectly good reasons so I've already abandoned the idea as you can see in my earlier post in this thread.

The presoak was supposed to be only for non-divided developers although I may not have been clear on that. I'll be testing uniformity with various experiments through the week but I think I may have screwed up in shortcutting fix and wash or in overheating the film in the Senrac dryer, will have to see. Regardless, it's certainly not boring.

 

[justpete]

There is a long thread on this about a month old. Most distilled water is pH 5.5 due to one of two factors. 1. the water absorbs CO2 from the air and 2. the stills are kept clean by washing the coils with acid to remove scale. Either way the water is more acidic than you might (or I might) expect.

Most tap water is about pH 6.5 - 8. Some cities add alkali to prevent corrosion.

Do not add alkali to the prewash though.

PE

Tnx, I remember the thread on distilled water, it was very helpful.

So far I've taken prewash off the list of possible 'fixes'. I've seen bromide drag-type streaking and full blown surge clouds but I've also seen some patterns I can't really explain although they appear to be surge-type patterns through and around the sprocket holes. And always on the top edge it would seem. Agitation is a lot trickier than I ever thought it would be, that's for sure. But what's a hobby without a challenge and some pulled out hair...

 

[Paul Verizzo]

There is a long thread on this about a month old. Most distilled water is pH 5.5 due to one of two factors. 1. the water absorbs CO2 from the air and 2. the stills are kept clean by washing the coils with acid to remove scale. Either way the water is more acidic than you might (or I might) expect.

Most tap water is about pH 6.5 - 8. Some cities add alkali to prevent corrosion.

Do not add alkali to the prewash though.

PE

Yeah, I remember that thread well.

I just checked my Sarasota city water and some Publix "Purified Water." I don't have any of the so-called distilled water, which in any case is just a cleaner version of RO water, I'm sure. I doubt if stills are used anymore except for lab quality juice maybe. City water here is a mix of surface and wells.

City water was about pH 7 or a tad under, the purified, 6.5. That's as best as I can read whole number pHydrion strips. Nowhere near 5.5, obviously.

 

[Photo Engineer]

Stills are better and cheaper than ever and are still in use.

PE

 

[Paul Verizzo]

PE, where do I buy a used still? My liquor habit is getting costly with the devaluation of the dollar and I should probably brew me some up at home.

Seriously, there is a market for DW stills? How could the market be anything but a ghost of its former pre-RO self? And the cost of the energy to run a still goes up daily, it seems. For photo work and almost anything non-lab, isn't good RO good enough?

 

[Photo Engineer]

Yes, there is a market for DW stills. They are about 2 x 1 x 1 and produce continuously (measurements in FEET). They need cleaning every few days with a special mix supplied by the mfgr and they produce copious amounts of DW.

As for distilling though, use an old car radiator. That is what the moonshiners used to use.

RO is good but expensive to start with, slow and replacement cartridges are expensive. It depends on throughput. See a tropical fish dealer that specializes in salt water products.

PE

 

[justpete]

That's as best as I can read whole number pHydrion strips. Nowhere near 5.5, obviously.

The 15roll set allows reading to within 0.2 (stepping through three rolls) although you have to be quick with the color comparison. The set's about $47 from Cole-Parmer, the lowest cost I found. FWIW.

 

[dancqu]

Yes, there is a market for DW stills.PE

Last I checked, about a year + ago, counter top
units were going new for about $100. Dan