Why did my Rodinal turn green when developing Fomapan 100?

Filippo Romani

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Hi everyone


Today I developed a roll of Fomapan 100 (120 format) using Rodinal 1+50 for 8 minutes at 21°C.
When I opened the tank, I noticed that the developer had turned a bright mint-green color and even the stop bath afterwards took on a slight greenish tint

When I develop HP5+, this never happens — the chemicals keep their normal color.
Is this green color normal with Fomapan 100?

And also: since the stop bath picked up a little bit of that green color, do I need to replace it right away, or is it still safe to reuse?

Thanks a lot to anyone who can help!
 

Alex Benjamin

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Hi Filippo

Welcome to Photrio.

Green colour comes from the dye from the anti-halation layer. Nothing to worry about. Many people pre-soak their Fomapan films to get rid of it beforehand, especially when working with re-usable developers. It doesn't affect development.
 

thinkbrown

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You've discovered what I call the forbidden midori

Like @Alex Benjamin said, it's from the antihalation layer present in the 120 and sheet film versions of fomapan. Worth noting that it's not harmful even in reused developer. I run replenished D96 and the green fades after a few days.
 

koraks

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Filippo Romani said:
since the stop bath picked up a little bit of that green color, do I need to replace it right away, or is it still safe to reuse?
Click to expand...

You can safely reuse the stop and fix. See also @Alex Benjamin's post above.


This is a bottle of ID62 developer I keep at hand for various purposes. It has seen a decent amount of Fomapan sheet film. I replenish it occasionally so I can keep using it. As you can see, it's quite green as a result of the antihalation dyes (which are not really a distinct layer as such on the film) dissolved in it. It's perfectly harmless.

If you find you have some remaining green dye in the film after processing, you can take a weak bath of sodium carbonate and rinse the film in that for 2 minutes. Then run it through stop bath and wash it. It should come out clean.

Also, welcome aboard - we're happy to have you!
 

loccdor

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But can you dye easter eggs with it?
 

Alex Benjamin

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koraks said:
it's quite green as a result of the antihalation dyes (which are not really a distinct layer as such on the film) dissolved in it.
Click to expand...

Indeed, important clarification. I wrote "layer", but it was a slip of the keyboard .
 

Alex Benjamin

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Filippo Romani

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Thanks a lot, guys super helpful!

Now I’m kind of excited to see what weird colors other films’ anti-halation layers might throw at me
 

mcfitz

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The Mystery of Foma green dye residue is extensive.

I've seen a residual green tinge in the stop bath used after printing with Foma fiber papers. Stop used is Foma Fomacitro stop bath.

It is quite strange, I have no idea why it occurs, but it is disconcerting since Fomacitro claims to have an indicator in it - but this happens with freshly prepared stop bath. But only when printing on Foma paper. And the classic indicator for exhausted stop bath is not green, anyway.

who knows? Not me...
 

mcfitz

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I find it's disconcerting when seen in the stop bath. For films, I know it's the anti-halation layer, but from developping paper? I don't understand this.

It calls to my mind the intense shade of green produced by deadly arsenic dyes commonly used in the 19th century for textiles, wall papers and paints. I know there is now no connection with arsenic, but it is an unusually vibrant green.

Scheele's green - Wikipedia

en.wikipedia.org
 

MattKing

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Filippo Romani said:
Thanks a lot, guys super helpful!

Now I’m kind of excited to see what weird colors other films’ anti-halation layers might throw at me
Click to expand...

The deep blue from Plus-X is sorely missed
 

thinkbrown

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I seem to remember Acros having a deep blue antihalation layer but honestly it's been so long that I don't quite remember
 
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