PDA

View Full Version : Lifetime of mixed developers


arcr1
19th February 2010, 01:43 PM
I've followed the thread (http://www.film-and-darkroom-user.org.uk/forum/showthread.php?t=2153) on replacements for Ilford Cooltone developer over in "Chemical Formulae", and noted the comments on extended lifetime of the mixed solutions.

This caused me to wonder: what makes a developer last a long time, and what makes it go off quickly? Oxidation of the reducing agent, I'm guessing, but is there more to it than that? For instance, I've read that ascorbic acid developers go off much quicker than hydroquinone developers because ascorbic acid oxidises much quicker in air, but a data sheet I read on the Moersch site said that the stock mixed from powder for one of their ascorbic acid developers will keep for 3 months, which (from memory) isn't that different from the advice on the label on my bottle of Ilford MG.

So can you really use the same dev over and over again? How do you know when you should discard it and use fresh? And (I wonder, because I'm coming to the end of a bottle) do I really need to mix fresh MG dev every session, if I'm only processing 10-15 sheets of 10x8 RC one or twice a week?

Thanks for all your input!

Andrew

Dave miller
19th February 2010, 01:54 PM
This an interesting point that you have raised Andrew.
I use the non-technical system of discarding the stuff if it (a) goes a funny colour, or (b) stops working. However, I would like a definitive guide too.

Bob
19th February 2010, 03:52 PM
I use the time-to-appear method. I read that it is not really 100% accurate but I err on the safe side and I seem to be OK.

Time how long it takes for the shadow detail to start to show in fresh developer and discard the dev when that time increases by 25%. You can probably go much longer than that, but the stuff is generally cheap enough so why risk it?

My dev stays in my Nova slotty thing between use with the top of the slot sealed (ish) with cling-film between use (think of it as the same as pouring the developer into bottles between use but without all that air being pumped into it during the pouring). Typically it will stay in there for up to a month but different developers certainly last different times: when I used Ansco 130 I never found a case where it died of exposure - even after months in the slot.

B&W Neil
19th February 2010, 05:39 PM
Some say a mature developer does the job best; but unfortunately I can't remember who said it :) I certainly don't panic about having an aged developer in my slotty thing if the colour is right and it is still doing the business.

Neil.

vanannan
19th February 2010, 08:31 PM
Hi
A couple of weeks ago I mixed up a batch of Ansco 130 stock solution and then diluted 1 litre with 1 litre of water and made a few 10x8 test prints with which I was delighted, I then left the dev in a tray overnight and made a print the following morning which exactly matched the last print made the previous day, I repeated this the following day with the same resulton the fourth day I noticed a small reduction in density which I compensated for (approx. 10% increase in dev time, the dev was discarded after this but I am left wondering how long it would have retained full activity had I poured it into an airtight container between sessions.
I would not normally have attempted to keep a dev for more than 1 session and only did because I have to get my Glycin from the US and it is expensive.

Mike O'Pray
19th February 2010, 11:57 PM
Bob I take it that as you have a slotty thing then you raise the print out of the developer every couple of secs to check on the shadow detail. Presumably the raising and time to check doesn't affect the development? I wonder how long the dev on the print surface still keeps working before a further dunk is necessary?

I have always been a bit frightened to do this.

Ansco has always been popular in Scotland. It's relabelled MacAnsco and uses Speyside water. Locals call it the bawbee saver. It's so good at saving that they almost made it the Scottish goalkeeper.

It used to be Rough from Partick. Well it's nearly all rough from Partick.

As they used to say on Blue Peter after a dangerous stunt. Please do not try this in Glasgow unless you come from Partick.:D:

Mike

Bob
20th February 2010, 09:16 AM
My agitation routine is to move the print slowly for the first 10 seconds or so to let the paper soak up developer (for fibre paper, with RC there is no need) and then lift the print 90% up out of the soup every 5 seconds or so initially until the first sign of shadow detail and I lift it out every 15-20 seconds thereafter - moving it in a circular/side-side motion between times. This gives maximum agitation by keeping the developer in motion and hence well mixed.

The amount of developer in the emulsion will not get exhausted in the one or two seconds it spends out of the soup - probably not for 10 seconds or more if it spent that long out: after all, that's why it's called a Stop bath (tho not actually used for that these days as most papers develop more or less to completion - paper stop-baths are more useful to reduce alkaline carry-over into the acid fixer). Lift the print out just after shadow detail starts to show and you can watch it increase before your very eyes (assuming your safelight is bright enough).

Pour your A-130 into bottles between use - it will last almost indefinitely, even if it turns dark brown; just keep an eye on how long it takes to work and dump it when you start to feel too guilty about keeping it for so long :)...

The Scottish version that Mike seems to have been sampling last night should however be consumed as quickly as possible and further stocks laid in for emergencies...

Mike O'Pray
20th February 2010, 07:14 PM
Thanks Bob. I'll try and remember to give this a go next time I dump the dev and re-stock the slot. In my earlier days when I was in the darkroom almost every night, I used to use Nova dev and followed the replenishment system of so many prints and then dump 100ml and re-fill.

Often I'd find that it was less a question of dump a 100ml and more one of simply replacing a 100ml as the prints used up dev anyway.

It will be interesting to see if the replenishment method maintains the first sign of shadow detail time.

Mike

arcr1
21st February 2010, 12:21 PM
Thanks for your thoughts everyone, I guess I should now do some tests myself. I have tried re-using MG dev after 24 hours, and it seemed OK, but I didn't think to check the time for first appearance of the image.

I'm reassured though that keeping the diluted dev for re-use isn't such an outrageous idea!

I find the colour to be fairly variable after a session, or after storage, but I'll try to keep notes next time to see whether there's a correlation with age, effectiveness, number of sheets etc...

Andrew

arcr1
27th February 2010, 07:46 PM
Well, I had a session in the darkroom last night, and I thought I'd give it a go with some Ilford MG developer I'd kept from my previous session. That, apparently, was the 1st Feb, so the diluted dev had been kept in a plastic bottle (with an air pocket over it) for four weeks. It had gone a fairly yellowy colour, so I thought I'd just test one or two sheets and then mix up some fresh.

On my first test sheet of Ilford MGIV RC, the image first appeared after around 15 seconds in the dev, which seemed perfectly respectable, and after stop/fix and a quick wash, there were no peculiar colours or anything else out of the ordinary, so I carried on using the same dev for the whole session. All the sheets I processed look fine now they are dry, so it looks like the dev keeps way beyond the advice in the leaflet.

The only problem though was the smell - I presume that the yellow colour is actually bromine (released from the bromide in the dev) and the room certainly smelt bromine/chlorine-y. I'm not sure its too healthy to breathe much of that! I also don't know what effect that might have on the stability of the prints, or on the efficiency of the stop/fix Anyone know more chemistry than me?

Andrew

Mike O'Pray
27th February 2010, 08:37 PM
Andrew I have been on Ilford MG for many months now. It was prescribed by a Dr Galley from Mobberley after I had confessed to being a Nova dev addict:D:

The stuff sits in my slotty thing for weeks and OK while it is covered with a tube when not in use, it doesn't seem to exhibit any smell as you have described on being uncovered.

I am no chemist but I think if the smell was in any noxious after storage then the maker would be required to make this clear. At Leamington college on my nightschool course there were massive open trays of the stuff for a class of 20+ students and I never noticed any problem. Of course, there, it was dumped each night.

Mind you now I come to think of it, I did say to the wife that there were some students there who seemed to be getting big and ugly which was a bit frightening for me but she said that was OK as she'd noticed that over the weeks I had been there, I had grown just as big and twice as ugly :D:

Mike

Bob
27th February 2010, 11:55 PM
I'm not sure that chlorine compounds are at all common in developers, although presumably some will enter the developer from chloro-bromide papers in the same way bromide compounds do (and potassium bromide is a common constituent). No chlorine gas will have been generated as far as I have ever heard and bromine is a liquid at STP. If it were that would be a serious health hazard and I'm sure I would have heard of it before. The yellow colour (which will turn to brown and eventually black over time) is just oxidized developer.

I would imagine (and I'm not a chemist either) that the halides are tightly bound in their respective compounds and not available to become elemental - tho I suppose if you had a sufficiently strong stop bath (by which I mean conc. sulphuric or hydrochloric acid) some might be released via the carry-over from the developer ;). Or you could try sticking two electrodes in the developer and see what bubbles off :D

Seriously, I very much doubt any chlorine gas was given off but the usual ventilation recommendations should always be followed as far as practical in the darkroom. Generally the worse smell comes from the fixer which is often a nasty ammonia smell.

arcr1
28th February 2010, 10:16 PM
I'm not sure that chlorine compounds are at all common in developers

I'm sorry - I was just trying to convey the "halide-y" smell. I'm sure that you're right and there wasn't any chlorine given off at all.

bromine is a liquid at STP

But it still smells, doesn't it? I seem to remember that Iodine, which is solid at STP, also smells pretty strongly (but that's a long time ago and we could have been heating it up to make it sublime....)

However:

If it were that would be a serious health hazard and I'm sure I would have heard of it before.

...

Generally the worse smell comes from the fixer which is often a nasty ammonia smell.

I'm reassured! I've also had a trawl through the Ilford safety pages, and there is no mention of the release of halogens, just ammonia and sulphur dioxide. More reassurance.

I did feel a bit funny though when I'd cleaned up, so I'll look at my ventilation anyway.

Thanks again,

Andrew