PDA

View Full Version : when to dump fixer



brian steinberger
25-Aug-2005, 19:37
I' ve had my fixer for about 6 months now. I keep it in a gallon jug. How do I know excatly when to dump it? I use it for both film and paper.

David A. Goldfarb
25-Aug-2005, 19:43
I dump paper fixer at the end of the session.

Film fixer, you can test with a clipped film leader from some 35mm film or set aside a sheet of film to cut up for this purpose. With conventional films, fix for twice the clearing time, and with T-max fix for about three times the clearing time, and when the clearing time is too long, dump the fixer.

Brian C. Miller
25-Aug-2005, 22:15
I use hypo check. Couple of drops into the fixer, if there is any change then out it goes.

paulr
25-Aug-2005, 22:40
I trust everyone recovers the silver before dumping down the drain?

Calamity Jane
26-Aug-2005, 03:33
That's something I have never done PaulR

Is there an easy way to recover the silver?

What do you do with the silver afterward?

John Cook
26-Aug-2005, 03:50
Brian, both Ilford and Kodak have technical information online about all of their products, including fixer. This information includes both shelf life and capacity. Follow it. Much more accurate than advice from friends.

If you have difficulty remembering the number of sheets run through, string up some wooden beads on a wire over the sink, like they do in a pool room.

Here is the Ilford site:

http://www.ilford.com/html/us_english/bw.html

May I suggest the non-hardening Rapid Fixer?

paulr
26-Aug-2005, 09:09
here's what i learned from the chemical safety coordinator at my college ...

you can remove well over 99% of the silver through ion exchange just by throwing a wad of fine steel wool into your fix and letting it sit.

I do it in a small bucket. Over a few days th steel wool will mostly disolve and turn into black sludge at the bottom. you can pour of the clear liquid and dump it down the drain. The black sludge is mostly silver. Over five years or so of doing this I accumulated a small jar of black sludge, so it doesn't pose much of a waste issue. You could probably find someone who would refine the silver out of it, but the purity is low enough that it's unlikely that they'd pay you anything.

In some places, local commercial photo labs will recycle your fix for you, but in others it's illegal (mostly for dumb reasons, like hazardous waste transport laws).

Richard Ide
26-Aug-2005, 09:49
The problem with recycling silver recovered from fixer is mainly quantity. You might break even after paying refining and assay charges if you had maybe 50 ounces. Silver content is at least ninety percent. I have about 200 ounces left over and it is on my to do list. Someday I suppose!

Richard

John Cook
26-Aug-2005, 09:54
Living here in Massachusetts, where everyone is just too, too pee-cee I am already obliged to do the following:

My one and only family automobile has neither an eight-cylinder engine nor 4WD, and is made in another country (Canada).

I use only dolphin-safe tuna fish.

I am very careful never to say anything which possibly could be mistakenly construed as a compliment to my President nor anyone even remotely connected with the Defense Department (such as a Marine).

When I meet a man and woman with a small child, I never make the mistake of assuming they are married.

I havenít nuked a whale in decades.

When I encounter two men or two women with a child, I am careful to always assume they are married.

I feel extreme pangs of guilt every time I use a toothpick, knowing that a beautiful tree gave its life for my dental hygiene.

Every week I carefully sort and wash all of my trash into proper recycling bins (they refuse to take items soiled with traces of food on them). All solid waste is presented to passers-by in clear trash bags to prove I have nothing to hide.

I follow the local pooper-scooper law religiously, and have even learned to catch my dogís terds before they hit the ground.

So I am ecstatic beyond belief that no one from the sewer police is yet on my case over poring two lousy quarts of fixer down the drain every month or two.

But then, I must have to have something to look forward to in the future.

paulr
26-Aug-2005, 12:35
"The problem with recycling silver recovered from fixer is mainly quantity."

You'll never make a dime.

The problem with not recycling silver is polution. Silver thiosulfate is toxic in minute concentrations.

I have heard chemists cite theory and say that it is not a problem for sewage treatment plants ... but experience begs to differ. I've sat in on environmental hearings in colorado springs that were called together after multiple episodes of the waste treatment plants being shut down by photographic silver in the sewage. The result each time was tons of raw sewage passing into the environment. The perpetrators were found to not be commercial labs, which recovered silver to high standards. The problem was home and school and medical darkrooms.

Recovering most of the silver is so easy there's just no reason to not do it. Steel wool. That's it.

Richard Ide
26-Aug-2005, 13:06
Paul

Thanks
My post was not properly thought out.

Richard

Harold_4074
26-Aug-2005, 13:18
You might consider a separate bottle for film fixer, if for no other reason than to prevent the odd bit of dust or paper fiber from appearing on your dry negative. I know that these shouldn't make it through the wash, but....

An idea that I picked up somewhere (probably here!) is to put a strip of masking tape on the bottle, with the date and a column of little boxes, each representing 80 square inches (one roll, two 4x5s, etc.). After each use, the appropriate number of full or half boxes is blacked in, giving a sort of thermometer display of the remaining life. Experience or the manufacturer's data will indicate how many boxes to put on the new strip of tape that goes on when the batch of fixer is replaced. The twice-time-to-clear rule seems to be fine, since it has stood without major challenge for over half a century.

Paper---and particularly fiber-base paper---is another matter. The silver halide winds up complexed with sulfur compounds, which build up in the fixer, are hard to remove, and are apparently best extracted by fresh fixer. I use the two-bath procedure (strangely missing from any current literature that I can find) which involves two trays, a couple of minutes in each. When the first tray has reached about half of its nominal capacity (some 30 8x10s per liter, if memory serves) or starts looking icky from dust, the odd hair from my beard, or carried-over stop bath, it is dumped and the second tray demoted to replace it. The second tray is then refilled with fresh fixer, and about every third cycle both trays are dumped and the scheme restarted. With these ratios, the cost of fixer is about a tenth of the value of the printing paper, so it doesn't make much sense to try to stretch the fixer to its limits.

I would welcome an opinion from someone better qualified than I as to why two-bath fixing seems not to be commonly recommended these days. I understand the various schemes involving straight hypo, non-hardening first fixer, and the like for archival or toning purposes, but we are talking here about plain, old, Kodak fixer from powder. Also, there are occasional references to fixer having a storage (as opposed to usage) life, presumably related to oxidation of the sulfite or thiosulfate, but I have never seen anything authoritative on this. Anyone?

paulr
26-Aug-2005, 13:57
Harold, it's also a good idea to use different fix for your film because film fix should usually be hardening and paper fix usually shouldn't. And film fix is often a stronger concentration.

Two bath fixing of prints is largely to help remove byproducts of the fixing process from your prints ... particularly from the paper fibers themselves, which thiosulfate ions tend to cling to tenaciously. Most studies of printing workflows find that all else being equal, a 2 bath fix is better if you want your prints to last a long time.

i don't know anything authoritative about shelf life, but i have had fixer go bad (at least get nasty) after a couple of years of neglect.

paulr
26-Aug-2005, 14:01
"So I am ecstatic beyond belief that no one from the sewer police is yet on my case over poring two lousy quarts of fixer down the drain every month or two."

lucky for you, there are no sewer police on their way to lock you up. Most state environmental organizations have dedided against regulating home darkrooms, because there's just no way to enforce any rules.

It's purely up to you. I notice a lot of posts from you about how the world is going to hell. This is chance for you to decide if you want to help make things even worse, or not.

Oren Grad
26-Aug-2005, 14:03
film fix should usually be hardening

Why?

Harold_4074
26-Aug-2005, 14:46
paulr:

Excellent points with respect to hardener and concentration. Since I use the Kodak stuff, I suffer from hardener effects when spotting prints (but not that much...) and use the same concentration for both film and paper. But other fixers do call for a higher concentration when used for film, as you correctly point out.

Oren Grad:

I understand that today many films are pre-hardened, but there was a time when most were not, and development in a strongly alkaline formula at high temperature could result in an emulsion that would come apart if you touched it while wet. (Don't ask me how I know this....)

Also, unhardened gelatine is more permeable to water and swells more. This is good if you want to a) have spotting dye sink in easily, b) let toning chemicals diffuse easily, or c) want the fixer remnants to diffuse out readily. It is not so good if you want to a) be able to handle the wet film without damaging it, b) have it dry quickly, or c) be able to subject it to abrupt temperature changes without causing reticulation.

Hans Berkhout
26-Aug-2005, 17:45
If I remember correctly Bruce Barnbaum has used old fixer as lawn fertilizer, with good results.

paulr
26-Aug-2005, 22:53
personally, I'd do a little more research before pouring silver ion-laden toxic effluent on my lawn.

John Berry ( Roadkill )
28-Aug-2005, 11:15
I use TF-4 and like it a lot, no acid in my process anywhere. I use seperate fixers for film and paper. Film will clear in 10 seconds when fresh. I still fix for 3 min. When it wont clear in 30 seconds I toss it. I used to make it my paper fixer but researh indicates the're residuals from film that is best kept out of paper.