Reuse of Pyrogallol developer

Silverhalide Emulsions / Chemistry.
HoloM
Posts: 89
Joined: Wed Jan 07, 2015 4:53 pm

Reuse of Pyrogallol developer

Post by HoloM »

Hi,
How long can I use a Pyrogallol developer ?
I have two solutions ,
Pyrogallol in water and sodium carbonate in water.

How long can I store both solutions?

If I mix both together for development, how long can I use it for development?
Only one hologram , or a few hours?
Any experiences?
Thanks
BobH
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Joined: Tue Jan 06, 2015 10:26 pm
Location: Mesa, AZ

Re: Reuse of Pyrogallol developer

Post by BobH »

The sodium carbonate solution should last a long time. Don't know about the pyro solution, but I'd throw it away just in case. After mixing, if there's no sodium sulfite in it, it only lasts a couple of minutes before it's useless. I recommend a one minute development time, and adjust your exposure to suit.
Din
Posts: 408
Joined: Thu Mar 12, 2015 4:47 pm

Re: Reuse of Pyrogallol developer

Post by Din »

I have had pyro for a longish time, several months I think. But, it does degrade. If it's a dirty brown colour, it's probably nearing the end of it's life. If it's jet black, it's dead. It'll last longer if you kept it in a dark, light proof container and seale the top as best you can, to prevent oxygen from getting to it. I keep mine in a jar designed for photographic developers, so it's pretty dark. By the way, I believe that pyro is on a list of banned items. I remember someone on the forum a while back finding out you can't get pyro anymore.

Having mixed it, it'll last a few hours. If you typically shoot a plate every fifteen minutes and develop for about a minute, as Bob recommends, then you can probably pass about ten plates. But, the tenth plate will not be as good as the first.

Note Bob's comment. You need to add the sulphite, and the above is assuming there is sulphite in the pyro. Without the sulphite, it won't last more than a few minutes.
lobaz
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Location: Pilsen, Czech Republic

Re: Reuse of Pyrogallol developer

Post by lobaz »

Here is a description of the pyro developer (by Ed Wesly) at wiki http://holowiki.org/wiki/Ewesly_/_Holog ... Pyrochrome or at Ed's pages http://edweslystudio.com/Formulae/Devel ... hrome.html.

My experience tells the same: the pyrogallol solution stays for a few days, the mixed developer for about 15 minutes. If I need to reuse the developer that oxidizes fast (such as the Ultimate developer; I did not do it with pyro), I suck the developer from the tray with a big syringe.

Note that adding (sodium) sulfite shifts the reconstruction colour towards shorter wavelengths - see for example Appendix 5 of Practical Holography (subsection Image color control) or W. Spiering's article linked from Ed's description.
Ed Wesly
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Re: Reuse of Pyrogallol developer

Post by Ed Wesly »

Thanks, Petr for a plug for my web site. It says a lot about the usefulness of a 1% pyrogallol solution, in use since the days of Lippmann photographs! Colour Holographics still recommends its use on the last Data Sheet I had seen from them.

I just mix up enough for whatever I figure I might need for the shooting session so I don't have any left overs. With a flat bottom tray I can get by with only 50 mL of mixed solution per 4" by 5".

An economy trick is to use something that is available in most every large grocery store around the world, Washing Soda, which is sodium carbonate. Some brands have surfactants that make foamy suds when agitated and things that make clothes smell better, but it doesn't seem to hurt the diffraction efficiency. Those of you who have some of my 70mm skull holograms and Zone Plates have film developed in that kind of brew.

Another store where you might just be able to walk right in and walk right with sodium carbonate are specialty shops for pools and spas. Sodium carbonate is used to raise the pH of your hot tub or Jacuzzi, and usually sitting next to it on the shelf is the pH lowering powder, sodium bisulfate, aka sodium hydrogen sulfate in the UK, which makes sulphuric acid when dissolved in water. 2.82 grams of this powder is equivalent to dissolving 1 mL of 48% sulfuric acid solution in water. Use it in the Pyrochrome bleach or your favorite Fe EDTA formula.

A useful perversion of the Pyrochrome silver solvent reversal bleach is to add potassium bromide to it. 2g potassium dichromate, 6 g sodium bisulfate, 30 g KBr and you have a rehalogenating bleach on a par with the copper sulfates and Fe EDTA's and PBQ's. What is great about it is that it destroys the sensitizing dyes so that the hologram looks as clear as a window. Some emulsions don't take to it that well, like the Harman Holo Fx, but it worked swell on old Agfa Holotest and Sphere-S GEO-3.
"We're the flowers in the dustbin" Sex Pistols
lobaz
Posts: 280
Joined: Mon Jan 12, 2015 6:08 am
Location: Pilsen, Czech Republic

Re: Reuse of Pyrogallol developer

Post by lobaz »

Ed Wesly wrote:What is great about it is that it destroys the sensitizing dyes so that the hologram looks as clear as a window.
That's interesting, Ed. I thought that Colour Holographic BB640 plates treated in pyro developer + Fe-EDTA are brown due to gelatin tanning. Do you promise they get clean again?
Ed Wesly
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Joined: Wed Jan 07, 2015 2:16 pm

Re: Reuse of Pyrogallol developer

Post by Ed Wesly »

The brown is due to gelatin tanning by the pyrogallol. That stain can be removed by using a permanganate stain remover, http://edweslystudio.com/Formulae/Bleaches/S13.html. The dichromate in a reversal or rehalogenating bleach doesn't seem to effect the pyro stain.

I am referring to the sensitizing dye, the pale cyan coloring of red sensitive or slight orange of green sensitive materials. They can usually be removed by dissolving in alcohols, but dichromate renders them colorless.
"We're the flowers in the dustbin" Sex Pistols
lobaz
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Location: Pilsen, Czech Republic

Re: Reuse of Pyrogallol developer

Post by lobaz »

Great! Thank you!
jrburns47
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Location: Oyster Bay, NY

Re: Reuse of Pyrogallol developer

Post by jrburns47 »

Hi Petr & Ed,
I used to use the three step alcohol dry plus spray to dry my white light transmission holograms. A side benefit that I never thought much about was sensitizing dye removal although it was hard to miss the color change of the first alcohol 50/50 bath.

Now I’m using Pyrochrome process and also Nick’s #5 catechol Dev variations for Agfa 8E & Ilford and FeEDTA bleach with a final photoflo rinse before drying. Hadn’t thought about sensitizer removal. My question is, what are the consequences of using the Pyrochrome dichromate bleach with KBr versus an alcohol bath following FeEDTA bleaching? This would be for Agfa 8E75, 8E75HD and Ilford SP696T. Any guidance appreciated.

BTW, I’m now getting surprisingly (to me) good results using the pyrochrome process on 35-40 year old 10E75 NAH plates! Thank you Ed for that recommendation in your write up! The only thing is, that the old 10E75 wants 10X normal exposure for bleaching with Pyrochrome. I’m guessing that the 10E75 must have a sensitizer for red laser light. I don’t see any evidence of a residual sensitizer tint in the proceed plates. Does the Pyrochrome process remove the sensitizer at some point?
Martin
Posts: 131
Joined: Sat Apr 04, 2015 2:36 am

Re: Reuse of Pyrogallol developer

Post by Martin »

jrburns47 wrote: Sat Jan 15, 2022 10:56 am A side benefit that I never thought much about was sensitizing dye removal although it was hard to miss the color change of the first alcohol 50/50 bath.
Not sure but the change in color of your 50/50 alcohol bath you noticed may also stem from the acutance dye.

jrburns47 wrote: Sat Jan 15, 2022 10:56 am My question is, what are the consequences of using the Pyrochrome dichromate bleach with KBr versus an alcohol bath following FeEDTA bleaching? the sensitizer at some point?
Perhaps better printout stability at lower DE possibly.

That said, Jeff Blyth (http://d-i-yscience.blogspot.com/2016/0 ... s.html?m=1) recommends a print-out bath:
40 g. Sodium persulfate (or ammonium or potassium persulfate)
40g. Sodium hydrogen sulfate
DI to 1 litre.

3 minutes in this bath followed by a very brief rinse in DI gives good print-out resistance. (Always make sure that your final rinse water is free from any traces of developer ).

Interestingly, this solution can also be used as a solvent ("reversal") bleach.
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