Reuse of Pyrogallol developer

Silverhalide Emulsions / Chemistry.
BobH
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Re: Reuse of Pyrogallol developer

Post by BobH »

Din wrote: Sun Jan 23, 2022 10:25 am Fresnel reflection need to be considered, since such reflection diminish the actual radiation entering the plate.
Yeah, I forgot about that. But beam ratio is usually bracketed too, so it doesn't really matter.
jrburns47
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Re: Reuse of Pyrogallol developer

Post by jrburns47 »

No I haven’t been squeegeeing the plates after photoflo. Always having been a white light transmission holographer, I missed out on that whole squeegee thing. I have them now and guess I’ll have to “bite the bullet” and learn the technique, especially since ATF has jacked up the price of ethanol by ten times via arbitrary tax😡. Assume it’s some combination of the corn, oil & gas, and liquor lobbies in DC. Used to be $20-30 for 5 gallons of 99+% ethanol & now it’s $450-550. Methanol is still pretty cheap but a little to hazardous to health. My very nice used Labconco ductless fume hood, in my home lab basement, isn’t nearly as effective as my old commercial environment fume hood.
jrburns47
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Re: Reuse of Pyrogallol developer

Post by jrburns47 »

For those who might be interested, here’s a corrected & reannotated photo of first successful “quadrant” exposure test 014-02-2022 (Julian date, exposure # that day, year) on 4x5” 10E75NAH. The total power at plate was ~35mw 660nm w/ an avg. 7:1 beam ratio, open aperture achromat H2 transfer from a ruby pulse 12x16” portrait master both RB & OB collimated. That would be about 350,000 ergs/s/cm2. Pyrochrome processing, Dev: 4’, Bl: 2’, photoflo final no squeegee.
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jrburns47
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Re: Reuse of Pyrogallol developer

Post by jrburns47 »

Again, for those who might be interested, here’s an annotated photo of first successful “quadrant” exposure test 022-02-2022 on 4x5” 8E75HD. The total power at plate was ~25mw 660nm w/ an avg. 4:1 beam ratio, open aperture achromat H2 transfer from a ruby pulse 12x16” portrait master both RB & OB collimated. That would be about 250,000 ergs/s/cm2. Nick’s #5 processing (not quite same version as on Ed’s developer list) Dev: 3.5’, Bl: 2’40”, graded ethyl alcohol/H2O, (50/50, 75/25, 90/10, 99+% spray. Photo not as good as holo😮🤪.
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jrburns47
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Re: Reuse of Pyrogallol developer

Post by jrburns47 »

Two questions:
- is there a meaningful study, or other information, discussing how much of a sensitivity increase occurs with a TEA pre-soak, and what percentage of solution is best for different silver halide emulsions? My assumption is that Colour Holographics must have done a fair amount of study since they have specific recommendations for their BB plates - what about other emulsions?
- all my best silver halide holograms decades ago were done on 8E56HD/Millimask @514.5nm. They were processed at about 68F using GP-61 dev, distilled water rinse, F-24 fix, 10-15’ filtered H20 wash, GP431 bleach, 10-15’ filtered H2O wash, distilled H2O spray & graded ethanol dry and into drying cabinet. Usually they would then get laminated to a glass plate. To the best of my knowledge, none of those plates ever experienced a print-out issue. Now, I’m trying out various new processing regimes with some success thanks to many of you, and particularly Ed Wesly’s great website and emails back & forth with Ed, Hans & Mike Medora. My question is, which of the various processes will suffer from print-out if not “final rinsed” with potassium iodide or the persulfate rinse mentioned in a prior post by Martin Richardson, and which “printout prevention” treatment is best with which processing regimes?

Any guidance will be gratefully received.
jrburns47
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Re: Reuse of Pyrogallol developer

Post by jrburns47 »

After a lot of back and forth about the total non exposure response I’ve been experiencing with old (30+ years?) Ilford red sensitive SP696T plates, I think I’ve found the problem. It doesn’t appear to be fogging or dark reaction per se but seems to be gross insensitivity. Without presensitizing it requires a massive exposure. As soon as I start testing my few old HRT BB640 4x5s, I’ll try presensitizing the SP696T and see if that helps. See photo with annotation. Interestingly, it doesn’t seem to be an issue with the Ilford green sensitive SP695T plates which expose normally.
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jrburns47
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Re: Reuse of Pyrogallol developer

Post by jrburns47 »

HRT BB640 4x5” 20 data point test
HRT BB640 4x5” 20 data point test
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Back with an update:
Photo is the second HRT BB640 test plate. The first had absolutely nothing on it because all four exposures were way too short.

I HATE squeegees! I haven’t mastered the technique yet obviously. There’s got to be a better way. I squeegeed after the TEA presensitizing and after the final photoflo rinse. I did the TEA presensitizing at about 1-1.5% @26C. Based on two other similar TEA presensitized 20 data point tests on very old Agfa 8E75HD & Ilford SP696T 4x5” plates, I estimate that I’m getting about a 2X increase in exposure sensitivity from TEA.

I also dislike photoflo. I was always a graded alcohol dry person for my white light transmissions. No squeegeeing or photoflo. Just very clean perfect plates…

BTW, the hologram image itself is cleaner and sharper than it appears in the photo - it’s a screenshot from a short video clip.

My takeaway from this 20 datapoint test plate is that the 20 second & 40 second exposures are best and that the 4 minute development is best.

The hologram numbering system is the Julian date day of the year, the exposure # that day, followed by the year.

The H2 “open aperture” camera setup is a 12x16” ruby pulse portrait H1 to a 4x5” H2, both H1RC & H2RB collimated, appx beam ratio 4:1, ~25mw at the H2 plate plane.

Any guidance about TEA presensitizing and squeegeeing and final drying will be gratefully received!

I think these German made HRT BB640 plates may be 15-20 years old.
Din
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Re: Reuse of Pyrogallol developer

Post by Din »

jrburns47 wrote: Tue Feb 15, 2022 9:47 pm I did the TEA presensitizing at about 1-1.5% @26C. Based on two other similar TEA presensitized 20 data point tests on very old Agfa 8E75HD & Ilford SP696T 4x5” plates, I estimate that I’m getting about a 2X increase in exposure sensitivity from TEA.
That sounds about right. My experience with BB plates was that it required an unsensitised exposure of about 1 - 2 mJ. Your 25 mW for 40 seconds gives 1 mJ, and 2X increase in sensitivity would make the sensitivity of unsensitised plates about 2 mJ. I exposed unsenitised BB520 for a range of 0.5 mJ to 5 mJ (from memory, as I don't have my notes handy) and got the best results in the mid-range.
Din
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Re: Reuse of Pyrogallol developer

Post by Din »

Correction. 25 mW (25 mJ/sec) for 40 seconds is 1 J, not 1 mJ. I must have read the 25 mJ as 25 microJoules, since that would agree with my results.
Martin
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Re: Reuse of Pyrogallol developer

Post by Martin »

jrburns47 wrote: Tue Feb 15, 2022 9:47 pm I was always a graded alcohol dry person for my white light transmissions. No squeegeeing or photoflo. Just very clean perfect plates…
Is it possible to have both TEA pre-treatment and alcohol dehydration? I don't remember having tried this. Unfortunately I've no access to my lab currently.

It may be important also to keep an eye on differing results from ethanol or isopropyl alcohol dehydration.

As for hypersensitization, I seem to remember some paper by a Spanish research group related to SHSG processing with Colourholographics materials. They pointed to increased photo speed by an alkali pre-development bath.

Incidentally, in regards to the shelf-life of outdated, very old holographic AgX materials I wondered about the lifetime of the sensitizing dye (provided there's no AgX fogging). Would it be possible to spectrally re-sensitize these old materials?
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