How do I test TF4?

[Sirius Glass]

1. How can I test TF4? Does Hypo test work?
2. How long does TF4 stay good?
3. How many rolls of film (135 or 120) can be fixed with one developing tankful of TF4?

Steve

 

[jim appleyard]

Yes, Hypo Test works. You can also dunk in the leader from a roll of 35mm and check your clearing time; it should be about 1 minute.

I can't speak re: # of rolls. I continue to fix until my hypo check tells me not too.

 

[pschauss]

If a piece of the film leader is an effective test of fixer, why use Hypo Test?

 

[Photo Engineer]

1. Yes. But remember that there are 2 hypo test solutions. You didn't specify. None really tests shelf life except a real dunk test as in post #2.

2. Almost forever unused.

3. An instruction sheet is included.

PE

 

[jim appleyard]

If a piece of the film leader is an effective test of fixer, why use Hypo Test?

Good question. In my case, it's because I bought a ton of Hypo Check before I learned about the clip test!

Anyway, many good photographers only do the the clip test and have never used Hypo Check. However, if you want to keep the good folks at Edwal employed a bit longer...

 

[Photo Engineer]

To be clear here, hypo check will only check for exhaustion of used fixer, but will NOT reveal if fixer has gone bad on the shelf. It is a simple solution of KI (Potassium Iodide) that turns cloudy yellow when it hits exhausted fixer and does so by forming AgI (Silver Iodide) which is a yellow cloudy precipitate. However, the test is qualitative in that even slightly used fixer will give a small amount of yellow precipitate.

Fixer that has gone bad on the shelf may test negative, but then may not fix film at all, therefore the dip test is the only reliable test for the activity of a bottle of unused fixer.

PE

 

[Sirius Glass]

Thanks PE, that is the information I was looking for.

Steve

 

[dancqu]

To be clear here, hypo check will only check for exhaustion
of used fixer, but will NOT reveal if fixer has gone bad on
the shelf.

However, the test is qualitative in that even slightly used
fixer will give a small amount of yellow precipitate.

...the dip test is the only reliable test for the activity of
a bottle of unused fixer. PE

Good point. Gone bad or going bad. With little to no
silver in the fix no precipitate will form yet the fixer
may have little to no remaining capacity.

Qualitative but not quantitative. That is a Big fault
with the test. Also the suppliers of the test vary in
their way of conducting the test and interpreting the
results. There is no standard. An irresponsible
oversight on the part of the industry. Some
instructions are even confusing.

Use of the test likely has much good fixer going down
the drain while others are using it beyond it's safe
silver levels. The test to my knowledge does not
indicate at archival levels. Actually who knows
at what levels the various versions do test?

Of course a post fix test for residual silver such as
the ST-1 can be used. I'm not sure though if it is
adequate to the job.

Fresh one-shot is my method. The testing has
been done before hand. My operation is greatly
quantified. Save for time available for work in
the darkroom. Dan

 

[Photo Engineer]

Use of Sodium Sulfide to test for fixing (washing) capacity is very good.

Also, use of Silver Nitrate in Acetic Acid is very good to test for retained hypo.

So, the use of all 3 (or 4 tests using the dip method) will tell you that the hypo is good/bad and the wash is good/bad. No need to use any other hypo eliminator or other chemistry.

PE

 

[BetterSense]

I have been told about the clip test, and I use it, but I have discovered something that makes me wonder if people aren't being misled.

I find that if a piece of film is exposed to room/daylight for a long time, that piece of film is much harder to fix than a piece that is fully exposed even to room light for several minutes. I theorize that the extreme exposure causes the emulsion to harden or polymerize or something.

I have found a large difference in fixing time between pieces of film that I have had lying on the floor for a long time, and the bits that I cut off of the end of the film I'm actually processing, which will only be exposed to light for about ten minutes. In fact I have found that aged examples of Tri-X (that I had saved for fixer-testing purposes) nearly impossible to clear, making me throw out a batch of fixer because I thought there was something wrong with it. The film hadn't cleared even after ten minutes, yet when I dunked a piece of fresh (yet fully exposed) film in cleared in only 2 minutes.

When doing the clip test, I am now careful to use a bit of the actual film I'm processing, and not the end of a 35mm leader or older piece of film.

 

[JBrunner]

I use the hypo test as a quick validation during printing. I use the snip test at the end of a session to determine to save the fix or not, and at the beginning of a session if I haven't been in the darkroom for a while.

 

[pgomena]

I once helped a friend with a big project. I processed about 80 rolls of T-max 100 in a gallon of TF-4. It was pretty much done for by the time roll number 80 went through. I had to lengthen the fix time of the last few rolls a bit.

Peter Gomena

 

[Sirius Glass]

1. Yes. But remember that there are 2 hypo test solutions. You didn't specify. None really tests shelf life except a real dunk test as in post #2.

2. Almost forever unused.

3. An instruction sheet is included.

PE

Arista Premium Hypo Check

Steve

 

[jmcd]

"I have found a large difference in fixing time between pieces of film that I have had lying on the floor for a long time, and the bits that I cut off of the end of the film I'm actually processing, which will only be exposed to light for about ten minutes."

I have not had this experience, but different films do have different fix times. For example, Ilford FP4+ clears in about 23 seconds in my film fixer; Foma in about 15.

Also, for the clearing test on a clip, it is helpful to first clear a spot on the end of the clip with a drop of fixer, then dip the end fully in fixer. This makes it easy to see the clear time, especially as the fixer approaches exhaustion.

 

[Photo Engineer]

A piece of film lying out in the light will form silver metal in a process called "printing out". This silver metal gives the appearance of having made the film harder to fix. It is actually due to the extra time it takes to remove this fine silver deposit that has formed.

Films vary in clear and fix time due to hardness, gelatin thickness, silver halide level and iodide level so one value will not fit all.

Here is a hint. Look at the base side of the film during this test. It will give you a more reliable view of things going on as you are looking at the time it takes for hypo to diffuse into and through the entire film.

PE

 

[Jeff Bannow]

I was thinking that since I shoot 4x5 mostly, and have no film leader, of just using a 35mm anyway. I could only pull out the amount needed for the test and then cut it, leaving the remainder of the film still inside the canister.