Dirty replenished developer...where's it coming from?

BetterSense · Sep 16, 2010

I keep 2L batches of D23 in clear plastic cranberry juice bottles. After a while, and it doesn't seem to correlate with how much film I'm running, it gets all dirty. The inside of the plastic bottle will be coated with a brownish substance and the developer will be cloudy with brown fog. It basically looks like dirty water out of flooded stream or something. If I filter it with a coffee filter, the whole filter will be brown from crud.

The performance of the developer does not seem to be affected but I'm getting tired of filtering it and putting it in new bottles. When I kept it in dark brown glass 1L bottles, I don't remember this ever happening--as long as I didn't pour out the very last bit of developer, it would come out crystal clear. But maybe I just couldn't see it through the brown glass. Do you think the developer is reacting with the plastic, or oxidizing on the sidewalls? Does anyone else keep replenished D23, and if so, what do you store it in?

Ian Grant · Sep 16, 2010

The 100 g/litre is mild silver solvent, you get some physical development with D23/D76. That's colloidal silver it forms in most replenished developers, some filter it out every so often.

You should decant your dev off before use, don't shake first. Same goes with reusing fixer. Agitation in deep tanks usually doesn't disturb the crud at the bottom

Ian

BetterSense · Sep 17, 2010

The thing is, I don't store the developer in the tanks, because they are hard rubber tanks with no lids. I pour the developer back in the plastic jug after every use.

Ian Grant · Sep 17, 2010

Should have added there's usually some gelatin from reels etc and traces of glues etc.

I meant decant from the bottle into the tanks, you can filter the last bit through a coffee filter to remove the sludge.

Ian

BetterSense · Sep 17, 2010

Well that's what I do now, but I find coffee filters very slow. It takes like 15 minutes to filter 2L through a coffee filter.

Ian Grant · Sep 17, 2010

Left overnight back in the bottle all the crud etc should sink to the bottom, usually you can decant at least 1700-1800ml of the dev off cleanly, leaving just a small amount to filter. If you can angle the bottle slightly so it falls to one edge of the bottom it's even easier.

My own system before & then after using much larger 12.5 litre deep tanks was to have a stock of 2.5 litres that I replenished, the advantage of that extra 500ml is you can work with at least 2 litres while the rest is filtering. My main Jobi 5x4 tanks (pre rotary) take 2 litres for 12 sheets, and the Paterson tanks use 500ml for each film.

Ian

Gerald C Koch · Sep 17, 2010

You have discoved why many people don't like replenished systems.

Coffee filters are not very good for photo purposes, either they are too slow or they pass too many solides. A better choice are lab filter papers which are available in many grades such fast, medium or slow filtration. You don't want analytical grade as it is much more expensive. You can also get a diameter which will fit your funnel correctly. There are also Chemex coffee filters which are made of lab flter paper. These are made for Chemex coffe makers. They are reasonable and very large so you can use a larger filter for faster filtration. BTW, cotton plugs don't work either. Google for Chemex filters or for lab supply houses.

You fold a filter first in half and then in roughly quarters. The second fold should be at slightly more than 90 degrees so the paper seals around the edge of the funnel. Moisten the folded paper with water, open one side and then fit it into the funnel. This helps to create a vacuum and speed filtration. Being careful not to stir up any sediment, fill up the funnel to just below the paper. Keep doing this until the very last bit of liquid. This prevents plugging up the filter until the very end.

BetterSense · Sep 17, 2010

I used filter paper a lot when I was in school, but I figured it might be even slower than coffee filters, plus I've never actually seen it for sale anywhere. I figure I could try to order it from a lab-supply place but I get tired of answering questions about what I'm building and why and that they don't sell to individuals.

Ian Grant · Sep 17, 2010

I have shelves full of lab filters many grades, but in practice I much prefer the coffee filter for filtering devs & fixers Faster but still efficient. Mine came with a job lot of darkroom equipment 10 years ago, I don't drink coffee at all and the wife will only drink Nescafe.

Sometimes I've just used some cotton wool, you place it in the filter funnel pass some dev though it then start again, the first flush removes the loose bits, after that it filters perfectly. loads of lab tricks

Ian

wclark5179 · Sep 17, 2010

You probably are providing an opportunity for mold to grow because of the previous contents of the bottle. Anytime I've used a bottle that has had either juices or other food products, like milk, I get the same results as you. Couldn't ever get all the stuff rinsed out as I believe just a little residue provides food for the devils to grow!

What's worked for me best are mt 2 liter soda bottles. But this may not be a good alternative as I understand some of the soda mfgrs. are now using biodegradable plastic. Perhaps some of the chemists here can enlighten.

pnance · Sep 17, 2010

I use coffee filters now, they're not slow, the lab filters I used to use were slooww...

When I want speed, I use tissue paper (like Kleenex, but specifically without perfume or other stuff). Works fast, isn't as good as lab, or coffee filter paper, but I found it adequate for the job, it gets the black stuff out.

When using any filter paper, but specifically tissue, I have a stainless steel drain filter I put in the plastic funnel, and the filter paper (or whatever) goes on top of that. This increases the amount of paper area that can drain. (paper touching the plastic funnel slows down filtering) Speeds up filtering 10 fold.

Paul

BetterSense · Sep 17, 2010

You probably are providing an opportunity for mold to grow because of the previous contents of the bottle. Anytime I've used a bottle that has had either juices or other food products, like milk, I get the same results as you. Couldn't ever get all the stuff rinsed out as I believe just a little residue provides food for the devils to grow!

I wonder if it is mold, because that would explain why it coats the inside of the bottle, and it would explain why I didn't have as much problem when I was using glass. I would have thought photo developer would kill mold, but maybe not.

Ian Grant · Sep 18, 2010

Colloidal silver builds up on the sides of some plastic bottles, because sulphite is a weak silver solvent it's plating out albeit weakly. This is far more noticeable with fixer solutions because of the far higher silver content.

Ian

Gerald C Koch · Sep 18, 2010

For best results in filtering it is good to invest a few dollars in a large plastic filtering funnel. You shouldn't have any problem getting one from a lab supply company. This funnel has a long stem to hold a column of liquid which creates a partial vacuun and greatly speeds the process. These funnels also have a number of ribs around the cone which lift the paper and provide more filtering area.. Get the lasrgest diameter funnel that is paractical for you. Chemex papers like lab filters are circular and flat, and the Chemex are 12 inches across. Youu can get a box of 100 for around ten dollars. Gormet food store often stock them also coffee stores.

In my own experience I find rapid grade filter paper to be faster than coffee filters. Even if you decide to use regular coffe filters I would fold them correctly and use a proper filter funnel. But then I'm a retired chemist.

BetterSense · Sep 18, 2010

I'd better be careful, it's illegal to own laboratory glassware without a license in Texas.

michaelbsc · Sep 18, 2010

BetterSense said:
I'd better be careful, it's illegal to own laboratory glassware without a license in Texas.

Are you really serious? The only thing I could think of would be trying to control illegal drug manufacturing, and if that's what you're trying to the lack of lab glassware is no impediment at all. Kitchen glassware would work just as well as it does for a photolab.

BetterSense · Sep 18, 2010

Unfortunately I'm serious.

Gerald C Koch · Sep 19, 2010

BetterSense said:
I'd better be careful, it's illegal to own laboratory glassware without a license in Texas.

Typical unthinking by a state legislature. Here in Florida we have to endure the clowns in Tallahassee. Most of the people who make drugs are going to use ordinary kitchen pots and pans. How do they define lab equipment anyway? To paraphrase Gertrude Stein; a funnel is a funnel is a funnel.

Dirty replenished developer...where's it coming from?

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