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Old 9th September 2019, 01:37 PM
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GoodOldNorm GoodOldNorm is offline
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Default Warning Vit-C powder loses its potency.

Just had a look at my Vit-C powder. I have had it for a few years and thought it may be out of date. It is 12 years old.Wow! "How time flies". Did a quick search on the net and found out that Vit-C loses its potency after 3 years from the day it was made. So I will have to buy some fresh. The reason I am telling you this is because I mixed up a litre of Vit -C developer and my film did not develop as expected.
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Old 9th September 2019, 04:22 PM
Mike O'Pray Mike O'Pray is online now
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Just out of curiosity, Norm does the packet have an expiry date and if it does, I wonder if this refers to its "medicinal" properties i.e. its actual vitamin C efficacy or maybe in the case of developer the two are in fact one and the same thing, so when it no longer provides vitamin C it no longer provides what's needed in a developer either

Mike
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Old 9th September 2019, 07:32 PM
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Quote:
Originally Posted by Mike O'Pray View Post
Just out of curiosity, Norm does the packet have an expiry date and if it does, I wonder if this refers to its "medicinal" properties i.e. its actual vitamin C efficacy or maybe in the case of developer the two are in fact one and the same thing, so when it no longer provides vitamin C it no longer provides what's needed in a developer either

Mike
Expiry date 2007 so it could be 15 years old which makes sense because I made some Gainer Vit-C developer back then. The developer I tried recently was: sod. Metaborate 1tsp, vitc powder 1/2 tsp, phenidone 4 ml of 1% solution in 1 ltr of distilled water. Use as soon as it is mixed.Suggested starting times:
400asa films 6 mins 30secs. 100 asa films 9 mins
Develop 2 films in the 1ltr stock then 2 more films + 20% of the developer time. 6 mins 30secs + 20% rounded to 8 mins. 9 mins + 20% rounded to 10 mins 50 secs.
I wrote this formula down on a scrap of paper many moons ago whilst browsing on apug. Tried it and got blank film, no wonder if my Vit-C powder was lacking in activity. I will try it again when I have the chemicals my Vit-C is dead and I have no phenidone left.
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Old 27th September 2019, 10:17 AM
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thanks for the info about the vit-c developer, GoodOldNorm!
Seems like an interesting developer. if you would compare the results, what other developer would you say it is close to?
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Old 28th September 2019, 06:44 AM
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thanks for the info about the vit-c developer, GoodOldNorm!
Seems like an interesting developer. if you would compare the results, what other developer would you say it is close to?
Hello Jonas, I have ordered some fresh vit-c and phenidone. When it arrives I will mix up the formula and give it a try.
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Old 28th September 2019, 07:42 AM
Anon01 Anon01 is offline
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Quote:
Originally Posted by GoodOldNorm View Post
Just had a look at my Vit-C powder. I have had it for a few years and thought it may be out of date. It is 12 years old.Wow! "How time flies". Did a quick search on the net and found out that Vit-C loses its potency after 3 years from the day it was made. So I will have to buy some fresh. The reason I am telling you this is because I mixed up a litre of Vit -C developer and my film did not develop as expected.
Interesting, I have mistakenly as a newby back again ordered Ilford in powder but can't see any use by date ???


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Old 28th September 2019, 08:39 AM
John King John King is offline
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Default Use by Date

Ilford have said in the past that their powder developers so long as the polythene packets are not opened, the life is almost indefinite. Even with other manufacturers the liquid developers 'use by' date is merely a guide, not definitive.
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Old 28th September 2019, 09:17 PM
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Commercial chemicals (powder and liquid) may be packed in an inert atmosphere (nitrogen usually I believe) so that may explain their long-life until opened.
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Old 8th August 2022, 01:50 PM
Nat Polton Nat Polton is offline
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I was idling through the various news channels on Youtube yesterday,
and an American news presenter mentioned the possibility of a serious trade squabble between the West and China. He mentioned a few important goods that we buy from China, all sorts of essentials, but the one that caught my attention was Vitamin C. Apparently we get loads of it from China, also Pyrogallol.
With the thoughts of more panic buying entering my mind I am thinking of buying a bit to put by for the future.

Wondering if it would keep for longer if I transfer it from the plastic tub into glass jars with taped lids?

Does anyone here decant their powdered chemicals into glass as soon as they get them?

Is glass better than the makers plastic tubs for long term storage ?

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Old 8th August 2022, 10:34 PM
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Ascorbic acid deteriorates faster if it's exposed frequently to atmospheric humidity. Sodium ascorbate less so, but obviously it's not suitable for many formulations.
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