How reliable is the film clip fixer clearing test?

runswithsizzers · Oct 12, 2022

MattKing said:
Actually, the change is mostly of no consequence for individual consumers, because mostly the shelf age of currently packaged fixer and similar products is immaterial - for individual consumers fixer lasts well past any likely "best before" date.
With normal storage - such as on a store shelf - the stuff really does last a very long time without problems.
Other products differ.

When you say "Other products differ." I am guessing you mean developer chemistry, right?

I'm pretty sure not many customers would pay full retail price for developing chemistry if they knew it was almost 2 years older than the manufacturer's recommended shelf life.

So who really benefits from hiding the age of the product from the consumer? The retailer makes a little extra profit by selling a product that would otherwise be difficult to sell. But in the long run, is that good for the future of film photography?

Some consumers are going to take the expired develper home and use it with no problems. Everybody is happy!

Some consumers are going to ask the manufacturer to check the batch code and reveal the age of the product. They may or may not get a refund or replacement product - but either way, the customer is inconvenienced, and confidence in the manufacturer and/or retailer will suffer.

Some customers are going notice the developer looks or smells funny. see above

And some customers are going to use the expired developer, and get poor results. Because it is often difficult to determine which part of the developing process caused the poor results, those consumers may get frustrated and decide film photography is just not worth the hassle. Score one for digital.

Rather than hiding the expiration date so the product can be sold at full retail price - the retailers would be better off to put short-date products on sale at discounted prices. They would make less profit, but they should have more satisfied customers in the long run. If a customer makes the choice to buy an out-of-date product to save money, they have only themself to blame if something goes wrong. That is different from a customer who feels they were tricked into unknowingly buying expired products.

Terryro · Oct 12, 2022

Doremus Scudder said:
...that would be the test for residual silver, not the residual hypo test. This latter tests whether the film or paper has been washed enough. A residual silver test is what you need to test for adequate fixation.

That said, a film-clearing test and a residual silver test should give you enough information to determine if your fixer is doing its job or not.

There are two readily-available ways to test for residual silver. The Kodak ST-1 test uses sodium sulfide:

Kodak® Residual Silver Test Solution ST-1
Distilled Water . . . . . . . . . . . . . . . . 125 ml
Sodium Sulfide (anhydrous) . . . . . . . 2 g
(This solution keeps for 3 months in a small tightly-sealed bottle.)

To use, dilute 1 part of the above stock solution with 9 parts distilled water. This working solution keeps less than a week. Squeegee your print or film and place one drop of the working solution on a border area. Let it sit for 3 minutes and blot with a clean cloth or tissue. Any discoloration other than a barely-visible cream tint indicates that your print or film still contains silver halides that require further fixing to remove.

An alternative is to use Kodak Rapid Selenium Toner. Kodak recommends a 1+9 dilution from stock, but tests show that a stronger dilution, even undiluted stock, works as well.

The directions are the same as the ST-1 test: wash your film or print adequately, apply a drop to the squeegeed material, let it for 3 minutes, blot and then check for stain. Any discoloration other than a barely-visible cream color indicates inadequate fixing.

I use the selenium toner test since I always have toner on hand.

If your old fixer clears film as fast as fresh fixer and the fixed material passes the residual silver test, you're good to go.

Doremus

Thanks for the information. I wasn't familiar with the Selenium test. Very good info. I've always used the clip test and doubled the clearing time until it's more than 4 minutes. Tossed if that happens.

MattKing · Oct 12, 2022

Retailers should be managing their inventory and, if they are reputable, pulling things like developer out of inventory if they have had them on the shelf for years.
The problem with date codes is that customers keep shoving the older stock to the back of the shelf and buying the newer stock instead, even when the viability of the older stock is essentially the same as the newer stock. The more that happens, the greater the likelihood that perfectly usable inventory becomes problematic.
It isn't like milk - fixer lasts for years!

Sirius Glass · Oct 13, 2022

Doremus Scudder said:
...that would be the test for residual silver, not the residual hypo test. This latter tests whether the film or paper has been washed enough. A residual silver test is what you need to test for adequate fixation.

That said, a film-clearing test and a residual silver test should give you enough information to determine if your fixer is doing its job or not.

There are two readily-available ways to test for residual silver. The Kodak ST-1 test uses sodium sulfide:

Kodak® Residual Silver Test Solution ST-1
Distilled Water . . . . . . . . . . . . . . . . 125 ml
Sodium Sulfide (anhydrous) . . . . . . . 2 g
(This solution keeps for 3 months in a small tightly-sealed bottle.)

To use, dilute 1 part of the above stock solution with 9 parts distilled water. This working solution keeps less than a week. Squeegee your print or film and place one drop of the working solution on a border area. Let it sit for 3 minutes and blot with a clean cloth or tissue. Any discoloration other than a barely-visible cream tint indicates that your print or film still contains silver halides that require further fixing to remove.

An alternative is to use Kodak Rapid Selenium Toner. Kodak recommends a 1+9 dilution from stock, but tests show that a stronger dilution, even undiluted stock, works as well.

The directions are the same as the ST-1 test: wash your film or print adequately, apply a drop to the squeegeed material, let it for 3 minutes, blot and then check for stain. Any discoloration other than a barely-visible cream color indicates inadequate fixing.

I use the selenium toner test since I always have toner on hand.

If your old fixer clears film as fast as fresh fixer and the fixed material passes the residual silver test, you're good to go.

Doremus

But it is still called hypo test. It states it right on the bottle, whether or not it is technically incorrect.

MattKing · Oct 13, 2022

Sirius Glass said:
But it is still called hypo test. It states it right on the bottle, whether or not it is technically incorrect.

Are you sure you are using the right bottle? A bottle of (residual) "hypo" test can also be purchased.

Doremus Scudder · Oct 13, 2022

Sirius Glass said:
But it is still called hypo test. It states it right on the bottle, whether or not it is technically incorrect.

Sirius,

There is a "hypo" test, but it is not a test for residual silver. It is the HT-2 test for residual hypo and tests for residual fixer and fixer by-products in the material being tested, not residual silver. It is, therefore a test for adequate washing, not adequate fixation.

Are you sure that is not what you are referring to?

Kodak® Hypo Test Solution HT-2
Distilled Water . . . . . . . . . . . . . . . . . . 750 ml
28% Acetic Acid . . . . . . . . . . . . . . . . .125 ml
Silver Nitrate, Crystals . . . . . . . . . . . . 7.5 g
Distilled Water to Make . . . . . . . . . . .1 l
(Store in a tightly sealed brown glass bottle away from strong light sources. This solution stains everything it touches, so don’t splash it around.)

To use for paper, place one drop on the border of the print, let it stand for 2 minutes, then rinse with water. If the print is thoroughly washed the solution will produce only a very faint tea-colored stain, or possibly no stain at all. If it is inadequately washed, the solution will produce a rather dark tea-colored stain. To judge the stains accurately you should purchase a Kodak® Hypo Estimator, which costs about $3.

To use for film, cut off a small piece of film and drop it into the test solution for 3 minutes. Properly washed films should show virtually no discoloration.

Photographer's Formulary sells both the HT-2 and ST-1 tests rebadged as their own products.

Best,

Doremus

Doremus Scudder · Oct 13, 2022

Terryro said:
Thanks for the information. I wasn't familiar with the Selenium test. Very good info. I've always used the clip test and doubled the clearing time until it's more than 4 minutes. Tossed if that happens.

Be aware that the film-clearing test has two functions. One is to determine if the fixer is still active and fresh enough to fix film adequately. For this, one needs to establish a baseline by testing a given film in fresh fixer and find the clearing time. Then as the fixer is being used, tests are made to see how the clearing time increases. When the clearing time doubles, or approaches twice that of fresh fixer, it means the fixer is exhausted and should be discarded and replaced.

The second function of the clearing test is to determine minimum fixing time for a given film/fixer combination. The fixing time should be at least twice the clearing time, which varies with the degree of exhaustion of the fixer. The film-fixing time for almost-exhausted fixer then would be 4x the time in fresh fixer (2x the clearing time for almost exhausted fixer doubled again to get the minimum fixing time).

When I fix film, I simply do a clip test in fresh fixer and multiply the time by 4 and then add a bit of a safety factor. It doesn't hurt film a bit to be fixed longer than the minimum time as long as you aren't letting it sit for a really, really long time. Then I don't have to do a clip test to find my fixing time for every batch, just test when the fixer is approaching exhaustion to make sure I discard it in time.

When I'm developing large batches of film, I use two-bath fixation. Not only is it more economical, but it ensures that everything gets fixed to the highest standard. I clip-test bath one and then replace it with bath two when the clearing time reaches twice that for fresh fixer. The second bath is then promoted to bath one and a new bath two is mixed. Exactly the same procedure as for prints.

Best,

Doremus

How reliable is the film clip fixer clearing test?

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How reliable is the film clip fixer clearing test?

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