mixing one-shot fixer?

[Poohblah]

so i know you can dilute developer to use once and then toss - can i do the same with fixer? about how much should i dilute from the concentrate (or stock solution) and how do i adjust the fixing time?

 

[brian steinberger]

I will assume that you're talking about film. The issue of using developer one shot is for consistency, which I do as well. My opinion is that there is no need to use fixer one shot. I mix up a liter of fixer in a working solution and use this solution until it is close to exhaustion, which is determined by using Edwals "Hypo Check." You could also mark down the number of rolls that you've fixed. I would recommend changing your fixer around 30 rolls. I always fix my film for 5 minutes. Re-using fixer is not only economical but also environmentally friendly.

 

[justpete]

so i know you can dilute developer to use once and then toss - can i do the same with fixer? about how much should i dilute from the concentrate (or stock solution) and how do i adjust the fixing time?

Yep, works fine depending on fixer I guess. At 1:14 w/TF-4 I get acceptable film clearing times and it'll handle a bit of acid carryover from a diluted TS-4 stop bath. YMMV of course.

 

[Poohblah]

yeah sorry i meant film.

so there isn't an issue with keeping mixed fix? my bottle of fix says a mixed batch of fix will only keep for 7 days.

 

[dancqu]

So i know you can dilute developer to use once and then toss
- can i do the same with fixer? About how much should i dilute
from the concentrate (or stock solution) and how do i adjust
the fixing time?

No problem. The only way I use fixer, film or paper.
With film I've had good results using 20ml of concentrate
in whatever solution volume needed; for myself, 120 - 500ml.
The more dilute the more time. Try 10 minutes with some
regular agitation. Dan

 

[Philippe-Georges]

The one shot fixer is used in some developing machines. I happen to use Acidofix (old Agfa stock) work diluted again 1 + 4 for 20 min. at 20°C, constant agitation (= rotation), 10 roll films (120 format) in a 2,5 L volume bath.
That's 50 mL Acidofix for one roll film.

Philippe

 

[Doremus Scudder]

Fixing one-shot is certainly possible. The question is if it is economical or not.

When fixing a small amount of film with a long time before fixing the next one is anticipated, then one-shot is likely the better solution.

Many use fix at higher dilutions than recommended by the manufacturer for one-shot fixing. Keep in mind that you need to ensure two things if you use this technique.

1. Fixing time must be adequate to ensure complete fixing. Fix for at least twice the clearing time of the same film. I prefer to fix for three times the clearing time.

2. You must have enough of the fixing chemicals to react with all the undeveloped silver halides in your film.

This is harder to determine, since capacities for fixers are usually not based on the presence of enough of the fixing chemicals, but on the build-up of contaminants. I would imagine, though, that a rather high dilution, say in the neighborhood of 1:20 could still contain enough thiosulfates to do the job provided you have a large enough volume. Usually, the fixing times get too long with higher dilutions before the too-little chemical point is reached. Mixing 1:20 is probably the practical limit on patience

I use fix one-shot when on the road and/or when I have just one or two sheets to develop.

Many recommend never reusing fixer because of the possibility of particles in the fix ruining film. I would agree with that. If you do use fixer over, filter it before use.

The best and most economical solution is to fix a number of films in one session. Either save up and do a number of films at once, or shoot more film...

Remember, do clip tests before each batch to determine the fixing time (clip tests are much more reliable than either hypo-check solutions or following capacity suggestions). Discard the fix when the clip time is twice the time in fresh fix.

Also, your used fix should last significantly longer than the 7-day figure you cite in a full, well-stoppered bottle. The 7-day figure is for fixer in an open tray. Do the above-mentioned clip test to check activity.

I now use a two-bath fixing method when fixing film when doing large batches. It ensures complete fixing, is most economical, and eliminates the need for constant testing.

Hope this helps a bit,

Doremus Scudder

www.DoremusScudder.com

 

[srs5694]

I mix up a liter of fixer in a working solution and use this solution until it is close to exhaustion, which is determined by using Edwals "Hypo Check."

Another way to test for exhaustion is a clip test. With fresh fixer, dunk a small amount of undeveloped film (such as the cut-off leader from a 35mm roll) in fixer and time how long it takes to clear. Fixer is exhausted when it takes twice as long to clear the same type of film as it does with fresh fixer. Note the phrase "the same type of film;" films vary in how quickly they clear. You should also fix film for twice its clearing time, so a clip test is a good thing to do as part of film processing. (Some sources say to fix for three times clearing time for T-grain films.)

so there isn't an issue with keeping mixed fix? my bottle of fix says a mixed batch of fix will only keep for 7 days.

Keeping properties of fixer depend on the specific brand and type. I believe that most commercial fixers will keep for longer than 7 days once mixed, although I just checked and couldn't find mention of this detail on the bottles of TF-4 and Kodafix I've got in my darkroom. (The TF-4 bottle did include a note that the concentrate shouldn't be kept for more than a year.) When it goes bad, fixer develops a precipitate and/or a rotten-egg odor. (I can't guarantee that the latter will be detectable over the strong ammonia odor of some fixers.)

 

[michaelbsc]

If you do use fixer over, filter it before use.

OK, how should one go about filtering it? I simply pour it back into the storage bottle using a funnel. Should I stick a paper coffee filter in the bottom of the funnel? Or a ball of cotton? (Boy, the cotton seems dangerous.)

Or I suppose if there's seems to be enough interest some enterprising soul will manufacture a "fixer filter" and we can buy them at stores just like buying oil filters at an auto parts store.

 

[kodachrome64]

yeah sorry i meant film.

so there isn't an issue with keeping mixed fix? my bottle of fix says a mixed batch of fix will only keep for 7 days.

I don't think you have to worry about this in a stoppered bottle. Maybe if you kept fixer out in a tray, where a large surface area was being exposed to air. I have kept stock solution longer than this, although I don't usually have a batch around that long.

I thought PE debunked the "silver particles floating around in used fixer and damaging the emulsion" theory, but I could be completely mistaken. Someone debunked it; someone whom I believe. I've never had an issue with it. The only issue I've had is using the fixer so much that it turned an amber color and actually stained the film. I wouldn't recommend being this stingy with fixer.

 

[CBG]

Hmmm,

I never had a problem of keeping used fix, nor have I had a problem with particles in used fix. I strongly encourage you to test your fix with Edwal Hypo Check or some similar solution. It gives you a really solid indication of when to trash your old fix.

Should you find it difficult to obtain Hypo Check commercially made, you can prepare your own:

According to www.digitaltruth.com/techdata/fixtest.php which has a lot of good info, this will make a hypo check:

Fix Test (Hypo Check)

Water 100 ml
Potassium Iodide 5 g

This solution should work well for modern rapid fixers based on Ammonium Thiosulphate, but for fix formulae based on Sodium Thiosulphate you may need to double the amount of Potassium Iodide.

Either solution should work fine as a basic indicator of fix exhaustion.

To use: Keep the solution in an eyedropper bottle (mark accordingly for safety).

Decant a small amount of fixer (approx. 10-20 ml) into a clear graduated cylinder and trickle a couple drops of the Fix Test into the cylinder.

If a white precipitate forms then the fix should be replaced.

If the solution remains clear, then the fix is fine.

Kodak's FT-1 is essentially the same but a stronger concentration.

Kodak Fixer Test Solution FT-1

water at 78° F*(26° C). 750*mL
potassium iodide 190*g
Add water to make 1.0*litre.

Testing the Fixing Bath

To 5*drops of Fixer Test Solution, FT-1, add five drops of the fixing bath and five drops of water. If a yellow-white precipitate forms instantly, discard the fixer. Disregard any slight milkiness.

Do not use this FT-1 solution for testing film fixer.

Best,

C

 

[ic-racer]

20 years ago in graduate school I used to re-use fixer and throw it out when it checked bad or after the manufacture recommendation of max. number of rolls. Twenty years later I have discovered negatives where the image is degrading. Usually from rolls fixed near the end of the fixer discard cycle (according to my notes).

I felt that re-using the fixer was one of those bad habits where the detrimental effects are not evident for many years.

I can scan an example to show, if you are interested.

BTW I usually use Ilford liquid ammonia thiosulfate fixer 1:4, one-shot for rotary processing film.

 

[Poohblah]

thanks for all the info!

i don't usually shoot more than one or two rolls of 35mm a week and i need the negs ASAP for printing in class to complete assignments. i'm sorta stuck between one-shot and keeping a mixed batch: if i use one-shot, 1:20 dilution, then i would use 30 mL of concentrate per two rolls of 35mm. that means that i could fix just under 40 rolls with my bottle of 500mL Ilford Rapid Fixer. but with the stock, 1:4 dilution, the bottle estimates that i could get 60 rolls with the 500mL of concentrate.

it seems to me to be more economical to keep a mixed batch of fix, and test it before i use it using either hypo check or by checking the clearing time.

however, ic-racer brings up a good point, and i don't want that happening either.

to be quite frank, i don't anticipate going through 40 rolls of film very quickly - i didn't shoot near that much in one semester. i'll use one-shot dilution.

 

[Larry.Manuel]

I have experimented with freezing my partially-used-up fix; regular strength Kodak, from powder. I mixed up half a liter [half the dry pkg.]. after several weeks, the fix was still good. I tested by the "clip test" as above. Otherwise my fix is mostly dead after about 10 days when diluted. My gut feeling is that 1:20 dilution might be a bit weak, but 1:8 or 1:12 may be fine.

Ilford Rapid Fixer [liquid] recommends dilutions of 1+4 or 1+9. That suggests to me 1+19 might still allow tolerable fixing times.

Good luck.

 

[Larry.Manuel]

Question for the group: If the fix is dead [I assume oxidized] but hasn't a high enough silver content to cause Hypo-Check to form a precipitate, will Hypo-Check really show that the fix is dead? My experience suggests no.

 

[Poohblah]

freezing is a good idea.

i just realized that i forgot the difference between 1+4 and 1:4.

 

[dancqu]

Question for the group: If the fix is dead [I assume oxidized]
but hasn't a high enough silver content to cause Hypo-Check to
form a precipitate, will Hypo-Check really show that the fix is
dead? My experience suggests no.

Good question. I've done a lot of fixer tests and one in
which the silver load was very low. A determination is not
possible because the point of formation of the precipitate is
indeterminate; the particles are so finely dispersed. The test
was with a very dilute fixer used one shot but should apply
to the more usual fixers.

I do not recommend roll counting. Films vary in their amount
silver. Agitation plus the in and out of bottle routine contribute
to oxidation. Fixer decay can be hastened by minute amounts
some impurities in the water. I think though that the film
clip test is valid. Remember, films can vary quite some
in their clearing time.

I have predetermined the amount of fixer and time needed
to thoroughly fix a few films. See my first post this thread.
There I mentioned 20ml of rapid concentrate in whatever
volume needed. Actually I had found 15ml per roll 120
enough but later due to aging concentrate added 5ml.

A few years ago I returned to the dry concentrate, sodium
thiosulfate, unadulterated and mixed fresh at time of use.
A quick fresh fix, no testing, rebottling, or filtering. Dan

 

[Poohblah]

I have predetermined the amount of fixer and time needed to thoroughly fix a few films. See my first post this thread. There I mentioned 20ml of rapid concentrate in whatever volume needed. Actually I had found 15ml per roll 120 enough but later due to aging concentrate added 5ml.

so, 30mL concentrate for two rolls of 35mm sounds right along with the 10 minutes and regular agitation mentioned earlier.

so, this dilution should last me just a few fixes? should i freeze the solution in a glass bottle if i'm not using it for a week?

 

[Photo Engineer]

Fix in any condition can deteriorate and precipitate sulfur which can damage film by being incorporated into the swollen gelatin causing spotting. Old, heavily used fix can accumulate so much silver that it begins plating out on the surface of the container or tray or tank! I have never heard of this being a problem as by this time the fixer is so shot it cannot fix film at all! Iron in fix can cause silver to precipitate.

You can dilute a fixer so much that it will begin to fix but the complex with silver and hypo cannot remain in solution due to dilution. In this case, the silver can begin to precipitate everywhere as all possible insoluable salt that can form.

PE

 

[Poohblah]

PE, you know far more about chemistry than me and i will heed your words of caution. like always, i'll run some tests first before fixing anything that i care about.

 

[Photo Engineer]

I appreciate your comment, but you are right to test. Test, test, test! Always test your process for retained hypo and retained silver. These test kits are easy to mix or available from most suppliers. They are accurate and help.

PE

 

[dancqu]

So, 30mL concentrate for two rolls of 35mm sounds
right along with the 10 minutes and regular
agitation mentioned earlier.

So, this dilution should last me just a few fixes?
Should i freeze the solution in a glass bottle if
I'm not using it for a week?

A one-shot amount good for two rolls. Toss after
use, do not store. I suggest trying A roll with 15ml.
Use the least solution volume needed.

I agitate the first minute then 15 seconds each minute
thereafter. After 5 or 6 minutes and in dim light give the
film a look. If clear give it another 2 to 3 minutes to be sure.
If not clear give that many more minutes and check again.
You'll need to test a roll or two if you wish to establish
a base time for any specific film.

Films vary in the time they take and amount of chemistry
needed. I've settled on 10 minutes to finish so supply
perhaps more chemistry than needed were the
fixing further protracted. Dan

 

[Poohblah]

thank you.

i'll test soon... varsity tennis is eating up my free time right now... and my film compartment in the fridge has seen better days.