Basic Photochemistry

[RalphLambrecht]

over the years, I collected a bit of photochemistry information and some standard recipes(formulae). Recently, I compiled it into a pdf and thought, I'd share it here. Hope it helps;It's meant for the non-chemists amongst you but I'm happy to consider comments from the pros.

 

[chris77]

over the years, I collected a bit of photochemistry information and some standard recipes(formulae). Recently, I compiled it into a pdf and thought, I'd share it here. Hope it helps;It's meant for the non-chemists amongst you but I'm happy to consider comments from the pros.

thank you, ralph. much appreciated!

 

[tezzasmall]

I used to mix most of my developers, in my teens = many moons ago now. Having bought 'the' book and some of the chemicals listed in it, I have been looking forward to trying out some of the formulae.

So, thanks very much Ralph, for PDF'ing this small but important part of the book.

Terry S

 

[Alan Johnson]

Two formulae given are not as usually given.

"Agfa Rodinal" given is not the formula of the proprietary developer but of PaRodinal;
http://www.martinzimelka.com/homepage/Blog/Entries/2012/9/10_Parodinal.html
https://www.photrio.com/forum/threads/parodinal-with-potassium-bisulfite.118849/
I am not convinced that in the formula given it is safe to add 20g sodium hydroxide to distilled water at 50C.
PaRodinal has an excess of hydroxide but if developed for 10% longer I cannot distinguish the results from those obtained with Agfa Rodinal.

"Crawley's FX-37" The starting amount of water should be 750ml not 250ml. It is diluted 1+3 not 1:25 or 1:100. The correct formula is given in Photrio recipes:
https://www.photrio.com/forum/resources/crawleys-fx-37-developer-for-t-max-delta-films.168/

But thanks Ralph for an excellent overall summary.

 

[RalphLambrecht]

thanks a lot for the comments. I will try to take a closer look and correct the formulae where necessary.

 

[DavidJRobertson]

Nice work. Here's my feedback:

• It's a bit unusual to call isopropyl alcohol "isopropylic alcohol".
• Also, it does seem to imply that Triton X-100 is identical to Tween 20, but these are different chemicals. In my experience tween 20 doesn't work as well for avoiding drying marks on film, though it is better than nothing.
• Might be nice to include a recipe for (non-stinky!) thiourea based sepia toner.

 

[RalphLambrecht]

Nice work. Here's my feedback:

• It's a bit unusual to call isopropyl alcohol "isopropylic alcohol".
• Also, it does seem to imply that Triton X-100 is identical to Tween 20, but these are different chemicals. In my experience tween 20 doesn't work as well for avoiding drying marks on film, though it is better than nothing.
• Might be nice to include a recipe for (non-stinky!) thiourea based sepia toner.

tween 20 is much easier to find than TritonX in homeports of the world; such toner recipe is included.but thanks for the reply.

 

[Stephen Prunier]

Thanks Ralph.

 

[Ko.Fe.]

Great! And thank you for this! No freaking oz and gallons .
Page 509 is empty for my notes, I guess.

 

[RalphLambrecht]

Great! And thank you for this! No freaking oz and gallons .
Page 509 is empty for my notes, I guess.

Yes, exactly. I have my own thoughts and opinions on units; having lived and worked in both metric and English-unitcountries, I don't mind either snd think they both have their purpose. I prefer(just out of habit)metric units for metal and lab work buttes English units for paper,wood and plumbing. Metric seems to be easier for me for all engineering calculations and to convert units. I don't see what the big problem is with working in either unit. All, I get chilly at 0C or32F just the same.

 

[NedL]

Thanks Ralph,

Has SFT-9 actually been tested? The variations I've tried so far certainly do tone like a sulfide toner, but the maximum toning was a mid-tan color... I didn't feel like it was ready to use on real prints yet. I tried sodium carbonate but not sodium hydroxide.

Should it be sodium sulfide instead, until the other has been tested more?

 

[RalphLambrecht]

Thanks Ralph,

Has SFT-9 actually been tested? The variations I've tried so far certainly do tone like a sulfide toner, but the maximum toning was a mid-tan color... I didn't feel like it was ready to use on real prints yet. I tried sodium carbonate but not sodium hydroxide.

Should it be sodium sulfide instead, until the other has been tested more?

Yes, I've tested it except for an accelerated age test but so far, it looks like it does exactly what was intended; a mild direct sulphide toning, slightly warming the image tones and adding 'archival' image protection with a very simple formula and widely accessible materials; not entirely odor free but nothing like the typical sulphide toners either.

 

[NedL]

Yes, I've tested it except for an accelerated age test but so far, it looks like it does exactly what was intended; a mild direct sulphide toning, slightly warming the image tones and adding 'archival' image protection with a very simple formula and widely accessible materials; not entirely odor free but nothing like the typical sulphide toners either.

Very good, thanks! And I should revise what I wrote... I tested it as a developer ( with an eye toward using it to re-develop in reversal ), not with an eye toward what it does to already reduced silver. I can imagine it works nicely on a developed and fixed print. Cheers!

 

[RalphLambrecht]

Very good, thanks! And I should revise what I wrote... I tested it as a developer ( with an eye toward using it to re-develop in reversal ), not with an eye toward what it does to already reduced silver. I can imagine it works nicely on a developed and fixed print. Cheers!

No,that has not been tested yet. Mainly because, I'm only a fan of direct sulphide toning; never liked indirect toning much.

 

[LifesShort]

Thank you very much for this. While I have no desire to mix my on chemistry, it's good to understand during the developing and fixing processes. Thank you for this easy to understand explanation of what is going on in my processing tank.

 

[RalphLambrecht]

Thank you very much for this. While I have no desire to mix my on chemistry, it's good to understand during the developing and fixing processes. Thank you for this easy to understand explanation of what is going on in my processing tank.

thanks for the nice words; you are more than welcome.