Reduced bleaching?

RLangham · Aug 10, 2020

So I like the look of bleach bypass a lot. Unfortunately I do a lot of manual photography and often err on the side of overexposure with color negative film. Overexposed negatives, when processed with bleach bypass, often get blocked and become unscannable to my ancient Epson scanner. In such situations I usually have to selectively bleach individual strips of film until they clear up, which loses the bleach bypass look entirely.

Does anyone have experience with reducing the bleaching time so that the negatives are partially cleared but still have some B/W negative layer remaining to give it that added contrast? What's a good time to use? My Cinestill kit has a Blix bath that takes 8 minutes at 102 degrees, but I have some unmixed chemicals lying around and I can make a separate bleach bath if I need to.

koraks · Aug 10, 2020

I think the best approach would be a highly dilute bleach to prevent unevenness. Haven't tried it though.

Bikerider · Aug 10, 2020

Buy a newer scanner

RLangham · Aug 10, 2020

Bikerider said:
Buy a newer scanner

I don't think that's a guarantee of it being able to get detail off a thoroughly blocked neg though. Also if this one breaks I can replace it for 30-40 bucks and keep my film carriers and software.

RLangham · Aug 10, 2020

koraks said:
I think the best approach would be a highly dilute bleach to prevent unevenness. Haven't tried it though.

I think with the prescribed agitation routine in a full-immersion tank like my Paterson unevenness shouldn't be a problem... after all, I am giving it the equivalent of one inversion every thirty seconds. At extremely short times, that would possibly be a problem, but the times involved should be at least several minutes.

I'm going to try six minutes at full temp later today and see if that adds any contrast. If not I can always save the negs by rebleaching.

koraks · Aug 10, 2020

I'm not sure the time with normal dilution of fresh bleach would still be several minutes for partial bleaching. My guess is it'll be in the range of 30 seconds to 1 minute or so.

RLangham · Aug 10, 2020

koraks said:
I'm not sure the time with normal dilution of fresh bleach would still be several minutes for partial bleaching. My guess is it'll be in the range of 30 seconds to 1 minute or so.

If that is true, then why is the standard blixer tine 8 minutes? The fixer doesn't take more than about 3 or 4 minutes to thoroughly and permanently fix--i use unmixed fixer from color kits as a B/W fixer and it clears film thoroughly in two minutes. The rule of thumb is to use the time it takes to clear film times two, so about four minutes for that particular dilution of ammonium thio...

koraks · Aug 10, 2020

The bleach I use for c41 needs something like 2 minutes according to spec. Old-fashioned c41 bleach was something like 6 minutes and that already included a healthy safety margin in all likelihood. I wouldn't benchmark against blix as that's a different animal where things like pH are a compromise between the bleach and the fix part.

RLangham · Aug 10, 2020

koraks said:
The bleach I use for c41 needs something like 2 minutes according to spec. Old-fashioned c41 bleach was something like 6 minutes and that already included a healthy safety margin in all likelihood. I wouldn't benchmark against blix as that's a different animal where things like pH are a compromise between the bleach and the fix part.

Well, if the fix is reducing the efficacy of the bleach, then 4-6 minutes may still be right on the money for partial bleaching. That being said, I would worry about partial fixing if the bleach is similarly interfering with the fixer...

koraks · Aug 11, 2020

Well, I definitely would not do this with blix in any case. That would complicate matters unnecessarily. Making a properly balanced blix is one thing; then modifying its chemistry or its use for partial bleaching while maintaining complete fixing is quite another.

RLangham · Aug 11, 2020

koraks said:
Well, I definitely would not do this with blix in any case. That would complicate matters unnecessarily. Making a properly balanced blix is one thing; then modifying its chemistry or its use for partial bleaching while maintaining complete fixing is quite another.

I can always give it a second fixing bath in rapid fixer though.

koraks · Aug 11, 2020

That's a good idea.

RLangham · Aug 12, 2020

koraks said:
That's a good idea.

I decided to do a throwaway roll as a test to see if there would be incomplete fixing. I did it for five minutes in the Blix. It came out looking normal, possibly a bit more contrasty. Next I'm going to try three minutes and a separate rapid fix bath, or possibly mix up a separate bleach bath and bleach and fix separately.

Rudeofus · Aug 13, 2020

I can hardly believe, that regular image silver would create enough density to block the scanner. What most likely happens is, that the film you use has an antihalation layer made from tiny colloidal silver particles. It will depend on your bleach, whether this antihalation layer bleaches before the image silver goes away. Photographic literature knows bleaches which clear small silver particles before they bleach larger silver particles, other bleaches act in reverse order. You may have to test different bleaches to get good results.

RLangham · Aug 13, 2020

Rudeofus said:
I can hardly believe, that regular image silver would create enough density to block the scanner. What most likely happens is, that the film you use has an antihalation layer made from tiny colloidal silver particles. It will depend on your bleach, whether this antihalation layer bleaches before the image silver goes away. Photographic literature knows bleaches which clear small silver particles before they bleach larger silver particles, other bleaches act in reverse order. You may have to test different bleaches to get good results.

Now that you say that, it hardly seems right, does it? I forgot about the antihalation layer completely.

Now how do people normally do a full bleach bypass? Use film without antihalation backing?

koraks · Aug 13, 2020

I've had problems with a dysfunctional bleach in the past and I can assert that it does create problems when scanning the images. It's probably to do with the scanner software anticipating a limited density range when it is set to scan color negative, applying a boost to the captured signal. This tends to blow out highlights. I've had this happen with both an Epson flatbed scanner and a Minolta film scanner. Both scanners will scan slides with little difficulty, but when set to color negative to scan unbleached negatives, problems do occur.

RLangham · Aug 13, 2020

Well, have you had any luck with adjusting the exposure settings on the Epson? I never have on mine... I just turn off grain reduction, dust removal and color restoration (because all three are very primitive on the old software) manually mask out the frames, and let the default settings do the rest, so I have no idea what the scanner can actually do if you change the settings. It's an Epson Perfection Photo 3170, by the way.

koraks · Aug 13, 2020

All of those things are my default settings. The affected negatives scanned poorly nonetheless, even when manually adjusting the curves during scanning.

RLangham · Aug 13, 2020

koraks said:
All of those things are my default settings. The affected negatives scanned poorly nonetheless, even when manually adjusting the curves during scanning.

That has been my experience about three quarters of the time when scanning bleach bypassed negatives. Maybe blocked was the wrong word earlier. Highlights blocked, midtones very dense.

koraks · Aug 13, 2020

I've printed optically from such negatives as well. Contrast through the roof! It did work for some images - not for most, though.

RLangham · Aug 13, 2020

koraks said:
I've printed optically from such negatives as well. Contrast through the roof! It did work for some images - not for most, though.

God, eventually I'll get a cheap color lens with integrated variable filters from Russia and try color printing... but that day is not today! Is the process as arduous as it sounds? I find regular B/W enlargements on multigrade paper difficult enough.

koraks · Aug 13, 2020

Color lens with integrated filter? I don't know about those; I just started out with a plain old dichroic head and some Schneiders and Nikkors I also used for b&w. Anyway, it's not super complicated; getting the filter settings right takes a bit of getting used to, but I personally don't find printing color to be necessarily more difficult than b&w. It's not extremely difficult to get a decent print in either b&w or color; making excellent prints is challenging in any medium. Just give it a go, it's the only way to learn.

RLangham · Aug 13, 2020

koraks said:
Color lens with integrated filter? I don't know about those; I just started out with a plain old dichroic head and some Schneiders and Nikkors I also used for b&w. Anyway, it's not super complicated; getting the filter settings right takes a bit of getting used to, but I personally don't find printing color to be necessarily more difficult than b&w. It's not extremely difficult to get a decent print in either b&w or color; making excellent prints is challenging in any medium. Just give it a go, it's the only way to learn.

Ah, see I have a 23c with only a condenser head.

Yeah, there used to be lenses, though, with three knobs on the lens barrel, that somehow introduce dichroic (I think?) filters into the light path. I think they were for enlargers that couldn't be converted to a dichroic head. Idk, I'm very new to traditional printing.

MattKing · Aug 13, 2020

koraks said:
Color lens with integrated filter? I don't know about those;

One of these:
https://vancouver.craigslist.org/van/pho/d/vancouver-pzo-janpol-color-80mm-56/7174830397.html

If you were local to Vancouver, you could go and pick one up - wearing a mask and with social distancing please.

MattKing · Aug 13, 2020

I don't think they use dichroic filters - more traditional ones instead.
I would suggest though that there are lots of used colour heads around for Beseler 23 series enlargers.

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