Which Black and White chemicals deteriorate through Oxidisation?

walliswizard · May 15, 2016

Oxidisation might not be the right word. It might even need a 'z' in there if you're in America, apologies either way.

I tend to use D76 mixed with de-ionised water, plus Ilford's Stop and Rapid Fixer.

I've just bought three packs of D76 powder, 1 litre each (rather then before when I'd buy the bigger 3.8 Litre pack), plus a special container that allows me to squeeze all of the air out of the bottle before sealing it.

I've read that doing this helps keep the chemicals for longer as the oxygen in the bottle affects the chemicals.

Is this also the case for the stop and fixer and if so how bad is it? Worth buying another two of those special bottles to keep those in too? (I probably will anyway, but I've spent enough for this month as it is!)

walliswizard · May 15, 2016

I suspect you won't like the spelling of "de-ionised" either

Sirius Glass · May 15, 2016

Paper developer oxidizes much faster than film developer.

MattKing · May 15, 2016

Ilford Stop bath doesn't keep well once working strength solution is mixed up. It isn't a problem with oxygen. Rather, it is a problem with the citric acid base - it provides an environment that promotes the growth of things you don't want to grow in your stop bath. I generally use it once and then discard, unless I am going to print again in the next day or so.

The much stronger smelling Kodak stop bath lasts longer, because it is acetic acid based.

The Ilford Rapid Fixer isn't susceptible to oxygen either. It (or the Kodak version) lasts well at the film working strength, if you use reasonably well sealed bottles. I prefer PET drink bottles.

I have kept the fixer at print strength over a couple of printing sessions, but usually I mix it fresh and then after the session put it aside for silver reclamation.

For developers, which are susceptible to oxygen, be careful of those "accordion style" containers. They are extremely difficult to clean and often are made of exactly the wrong type of plastic. A well sealed PET bottle with very little air between the liquid and the lid works better,

Photo Engineer · May 15, 2016

Developer and fixer both oxidize with time. The rates depend on storage and formula. There is no set method to determine this.

I noted Matt's comment just as I posted this. Fixer does oxidize.

Usually, developer is bad when it looks brown (D76 or Dektol) and fixer is bad when it smells like rotten eggs or has particles floating in it.

PE

Svenedin · May 15, 2016

I like your spelling!

I use those concertina bottles as well. Stop is very cheap as the concentrate is diluted so much. Most stops are acetic acid (vinegar) and so they will not oxidise (I note the post above that Ilford stop is not acetic acid though......). If you have an indicator stop you can tell when it's exhausted but I usually chuck it before that as it gets grotty. For fix I do re-use it but I do a test on a small piece of the film leader that I chop off when I'm loading the film onto the reel. When I pour the fix into the tank I put a small quantity of fix onto the tiny piece and note how long it takes to clear. Then I use twice that for the film in the tank. That way I can tell if my fix is good or not and whether it needs longer due to partial exhaustion. As for dev, if you want to be cautious with stored solutions then pour some onto a piece of exposed film (e.g. the chopped off leader) and make sure it develops to complete black in the time expected (you can do that in daylight). It's best to store your chemicals somewhere cool and use them up within the times suggested by the manufacturers.

MattKing · May 15, 2016

Photo Engineer said:
I noted Matt's comment just as I posted this. Fixer does oxidize.

Thanks PE. I guess I actually develop enough film in a short enough time to prevent this being a problem. .

I also use the same, well filled and sealed PET bottles, so that probably helps too.

This Kodak chart is informative: http://www.kodak.com/global/en/professional/support/techPubs/e103cf/e103cf.pdf

And of course, you could always refer to the Ilford instructions. Fixer: http://www.ilfordphoto.com/Webfiles/2011427111531653.pdf
Stop bath: http://www.ilfordphoto.com/Webfiles/2011427101531770.pdf

walliswizard · May 15, 2016

I threw my last batch of developer away, probably too early, but I thought I'd go with smaller batches properly sealed. I don't shoot a *ton* of film, a few a month at the moment perhaps, more for holidays, so if a litre keeps me going a month that's probably good.

And stop and fix I currently keep in old plastic milk bottles. Seems OK. I assume it's the developer that will have the most effect on the quality of the image. Again, I'll throw both stop and fix away every month or too if necessary. I've read of people keeping that stuff for a year or more. Seems daft to risk your negatives if you want to get the best out of them.

MattKing · May 15, 2016

Don't keep mixed up stop bath - discard after use.

Switch to soda pop bottles for the fixer - milk bottles breath.

Sirius Glass · May 15, 2016

MattKing said:
Don't keep mixed up stop bath - discard after use.

Switch to soda pop bottles for the fixer - milk bottles breath.

I keep stop bath until the indicator starts turning purple.

MattKing · May 15, 2016

Sirius Glass said:
I keep stop bath until the indicator starts turning purple.

Good, if you are using acetic acid based stop bath.

Dangerous, if you are using citric acid based stop bath.

spijker · May 16, 2016

MattKing said:
Good, if you are using acetic acid based stop bath. Dangerous, if you are using citric acid based stop bath.

I keep the mixed up Ilford stop in a PET bottle as well and keep it until the colour starts to change. So far I've never seen any growth in it. I mix it with plain city tap water.

tedr1 · May 16, 2016

Ilford publishes keeping time allowances in their paper chemistry data sheets. Some developer concentrates can be kept in air-free sealed bottles, but once diluted to working strength there is zero keeping allowance, use once and discard. My recent experience using Bromophen and Ilford Warmtone fiberbase paper confirms that within one day the developer has degraded.

For fixer I use the test strips available from CTL that indicate pH and silver content they come in sets of 100 for about $40 http://www.ctlscientific.com/cgi/display.cgi?item_num=90741

Neil Poulsen · May 17, 2016

Before use, I always check my fixer with fixer-checker. (Don't know the name offhand.) Put a drop in the fixer, and if you see the drop turn whitish, the fixer's no longer any good.

I don't have the chemistry background to know if this protects against oxidized fixer (I would think so; anyone?), but it protects against spent fixer.

I will also check periodically during a long printing session.

Very interesting bout the PET bottles. Will need to look into this.

Steve Smith · May 17, 2016

walliswizard said:
Oxidisation might not be the right word. It might even need a 'z' in there if you're in America, apologies either way.

No. That's perfect. Don't listen to any Americans who have invented a nonsense word oxidation. It doesn't oxidate so it's not a valid word!!

Steve.

Andrew O'Neill · May 17, 2016

Photo Engineer · May 17, 2016

It OXIDIZES!

The fixer tester is not reliable. It generally works very poorly for paper and just a bit better for film. A better test is to fix fresh film with fresh fixer, just a tiny bit will do, and record the time it takes to clear totally. Do this periodically and see what happens. Eventually the clearing time will just about double. That is just about the time to throw it out.

PE

MattKing · May 17, 2016

Photo Engineer said:
That is just about the time to throw it out.

Or more correctly, send it for silver reclamation.

Photo Engineer · May 17, 2016

Yes. Provided it went bad by use and not just age.

Andre Noble · May 17, 2016

Steve Smith said:
Don't listen to any Americans who have invented a nonsense word...

So true. In fact, our nonsense words are nothing compared our non sense phrases.

ColColt · May 18, 2016

and fixer is bad when it smells like rotten eggs or has particles floating in it.

Or, if it looks cloudy like what happened to me recently with just a two month old mix in a brown plastic bottle.

OK-What's a PET bottle?

RobC · May 18, 2016

anything you dilute with water will oxidize with time. Stock solution quite slowly if you keep air and light from it. But working strength developer very quickly.

Off the shelf developers which come as syrup (which is usually glycol or TEA based solutions) keep a very long time. Products such as Ilford DDX, Tetenal Ultrafin or Kodak HC110 are syrup developers and will keep for years undiluted. Once diluted to working strength I would use them one shot.

But a litre of D76 stock mixed from powder will develop how many rolls of film? Not many so how long do you need to keep it for before using it all. Not long enough for it to go off if you are using only a moderate amount of film. But I guess if you are chopping and changing the devlopers you are using all the time you will build up a stock of partially used stock solutions.

Other developers like pyro keep for ages too.

Some fixers such as hypam can precipitate out the sulphur if they are not regulary shaken up but the shaking up is likely to speed up any oxidation even if it is minimal.

For optimum developer stock keeping properties and low cost I would investigate mixing your own from raw chemicals using glycol or TEA. There are numerous formulas to be found on the web for this.

Photo Engineer · May 18, 2016

Does it still fix film with a clip test? (look up clip test here on APUG or contact me via PM). PET = Poly Ethylene Terphthalate bottle.

PE

MattKing · May 18, 2016

ColColt said:
OK-What's a PET bottle

The recycling symbol has a "1" in it - indicates it is made of Polyethylene terephthalate.

Plastic soda pop bottles are a good example - the ones for fizzy drinks.

You want to make sure the lids are good..

Julie McLeod · May 19, 2016

Are the PET bottles preferred over glass? I'm using old craft beer growlers (brown glass) but the caps are starting to get a bit rusty.

Which Black and White chemicals deteriorate through Oxidisation?

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