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Old 1st January 2022, 01:37 PM
Terry S Terry S is offline
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Default Oxidised chemical is lighter than fresh...

Browsing through the 'Optima' pod processor pages yesterday, (https://www.apurpleturkey.com/product-page/syringe) after it was mentioned again, in a post, I came across this statement:

'Oxidized chemical is lighter than fresh. When replacing chemical in a pod the Syringe with a tube cut to the right length allows the selective removal of oxidized liquid from the top of the pod, only if the pod is left to settle for 20 minutes before hand.'

Oxidised chemical is lighter than fresh and rises to the top (of the pod) after 20 minutes?!? That's the first time that I've heard that! Is it true?

I top up my Nova slot processor (which is similar in design, having vertical slots) at the end of a session with 10ml of working solution, for each 10" x 8" print I've made, as recommended by the Nova instruction sheet. If necessary, I drain off a little before doing so, using the tap at the BOTTOM of the processor. If the above statement is correct, I'm draining off GOOD developer and leaving 'bad'.

I've never noticed anything by doing it my current way, for years.

Does anyone else do it my way, or more importantly, the new quoted way?

Terry S
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Old 1st January 2022, 02:17 PM
Mike O'Pray Mike O'Pray is offline
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That's a new one on me Terry. I wonder what the science says?

Mike
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Old 1st January 2022, 02:54 PM
Richard Gould Richard Gould is offline
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New to me Terry, I tray process every print but when the developer is finished it is completely brown maybe it is a nova thing
Richard
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Old 1st January 2022, 05:08 PM
alexmuir alexmuir is offline
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I am not a scientist, but my understanding of oxidisation is that chemical changes occur in a solution when it comes into contact with air. Presumably, the solution (developer, wine etc) absorbs Oxygen from the air. If that is correct, the process must begin at the top of the Nova slot, where there is likely to be contact with air. This discussion is slightly confusing, as we know that oxidised developer looks darker, rather lighter. I’m assuming, however, that the word ‘lighter’ in the quoted passage refers to weight, rather than colour.
Anyway, if the solution remains undisturbed, the top is likely to be more affected by contact with air, although the contamination must reach the bottom of the slot at some point. In normal use, the solution in a slot will be mixed around when the print is agitated, causing the oxidised solution to be re-distributed in the slot, and allowing ‘clean’ solution to contact air at the surface.
When using the Nova, I normally top up the volume with fresh developer at the end of a session. I don’t usually remove some first. I tend to use a batch until it is exhausted, then replace the lot.
Alex


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