Caffenol chemicals?

[koraks]

Are higher speed films susceptible to fog and if they are why are they?

Yes, they are because they're fast. They're sensitive so they also respond more strongly to heat and background radiation.
I personally don't think an anti-foggant/restrainer is really necessary when using reasonably fresh or slow film.

 

[pentaxuser]

Yes, they are because they're fast. They're sensitive so they also respond more strongly to heat and background radiation.
I personally don't think an anti-foggant/restrainer is really necessary when using reasonably fresh or slow film.

Thanks Just to be sure, if a fast film, say HP5+ or Delta 3200 is reasonably fresh then KBr is unlikely to be needed? Assuming the user has properly stored the fresh film then at what age might it be affected by fog and if it might be affected, can you still simply print through it without it affectíng the print ?

Thanks

pentaxuser

 

[npl]

I tested 100 ISO film (fomapan 100) with and without iodized salt and could see a clear difference in fog level between the two. I prefer less so I use salt, but that didn't mean that the fog couldn't be print through.

 

[koraks]

Thanks Just to be sure, if a fast film, say HP5+ or Delta 3200 is reasonably fresh then KBr is unlikely to be needed? Assuming the user has properly stored the fresh film then at what age might it be affected by fog and if it might be affected, can you still simply print through it without it affectíng the print ?

That's what I'd expect, yes. Of course, a restrainer when added in small amounts will subtly affect the tonal curve, especially in the toe region. So the statement "without affecting the print" will always be a bit problematic if it's taken in a literal, absolute way. So I'd add "for all intents and purposes."

 

[pentaxuser]

That's what I'd expect, yes. Of course, a restrainer when added in small amounts will subtly affect the tonal curve, especially in the toe region. So the statement "without affecting the print" will always be a bit problematic if it's taken in a literal, absolute way. So I'd add "for all intents and purposes."

Thanks That covers it for me

pentaxuser

 

[Chuck1]

So iodized table salt will work instead of KBr, with less smell

 

[koraks]

with less smell

I'm surprised to hear that. KBr is odorless both as a solid and solution. I do think that bromine gas has a kind of 'poopy' odor. Is it possible that somehow a tiny bit of bromine gas evolves if KBr is added to caffenol?

 

[Chuck1]

That was a question, it has been mentioned over the part few days

 

[fs999]

So iodized table salt will work instead of KBr, with less smell

Not as good as Kbr. Here a test from Reinhold (imagesfrugales) :

 

[RalphLambrecht]

The water needn't be deionized; tap water will be fine.
You need some soda to speed things up though, otherwise you'll have a glacially slow developer.


Yes, you need those - at least the fixer. The other two you could omit. There's no DIY substitute for fixer.
For a stop bath, you can use (cleaning) vinegar or citric acid from the supermarket/baker's store.


Single use.

Correct! At the dawn of photography, in 1839, people such as Fox Talbot experimented with highly concentrated salt (NaCl) solutions, but they really didn't dissolve unexposed silver halides and their complexes successfully. Film and paper only get minimal protection and will continue to darken over time. In 1840, William Herschel discovered that sodium thiosulfate ("hypo") was far superior and actually worked properly as a fixer. This quickly became the standard because it genuinely dissolves unexposed silver compounds, while salt really doesn't. Consequently, as Koraks already said, there is no household substitute for a commercial fixer.

There's no DIY substitute for fixerIt is. Caffenol is a relatively expensive developer and I wonder if an LCA would support the eco-friendliness often attributed to it.

 

[ezphotolessons]

Correct! At the dawn of photography, in 1839, people such as Fox Talbot experimented with highly concentrated salt (NaCl) solutions, but they really didn't dissolve unexposed silver halides and their complexes successfully. Film and paper only get minimal protection and will continue to darken over time. In 1840, William Herschel discovered that sodium thiosulfate ("hypo") was far superior and actually worked properly as a fixer. This quickly became the standard because it genuinely dissolves unexposed silver compounds, while salt really doesn't. Consequently, as Koraks already said, there is no household substitute for a commercial fixer.

I believe it was 1819 he discovered how hyposulphite of soda works with silver compounds.

John Herschel: Sodium Thiosulfate (Hypo)

The first reliable fixing process

photography-collectors.com

Then again we live in a post truth world and this is the internet and photography-collectors could be wrong.

 

[titrisol]

Not as good as Kbr. Here a test from Reinhold (imagesfrugales) :
View attachment 410487

If that is caffenol, then salt help minimizing the stain (vitamin C does too)
which is different than fog

 

[koraks]

which is different than fog

I agree, that looks like staining, not fog.

 

[fs999]

If that is caffenol, then salt help minimizing the stain (vitamin C does too)
which is different than fog

But you need 20g/L, compared to 12g/L for iodised salt (0.0025 % iodate) and 1.2 g/L for Kbr.
With salt you will get dichroic fog, less with iodised salt and not with Kbr. Here the reference.