Fixer clearing agents

[herb]

I inherited a bottle of Adorama Wash Aid. The directions were 3 oz in a gallon of water. Seemed ok, used up the bottle, then went to my local shop and got Ilford Wash Aid. they recommend one part to 4 of water. The ilford is a sodium sulfite plus one ester of sulfite or some such, whereas the Adorama is Ammonium Bisulfite.

I have read the rather long thread on homemade HCA, but am still puzzeled about the huge difference in mix, not to mention the cost. Kodak has a packet of dry powder that will make more than the Ilford, which comes in a one liter
bottle.

Since I mix my own developer and fixer, it is the next step to make my own HCA, but the formulations are a puzzle.

 

[Roger Hicks]

I inherited a bottle of Adorama Wash Aid. The directions were 3 oz in a gallon of water. Seemed ok, used up the bottle, then went to my local shop and got Ilford Wash Aid. they recommend one part to 4 of water. The ilford is a sodium sulfite plus one ester of sulfite or some such, whereas the Adorama is Ammonium Bisulfite.

I have read the rather long thread on homemade HCA, but am still puzzeled about the huge difference in mix, not to mention the cost. Kodak has a packet of dry powder that will make more than the Ilford, which comes in a one liter
bottle.

Since I mix my own developer and fixer, it is the next step to make my own HCA, but the formulations are a puzzle.

2% sulphite, 0,05-0,2% EDTA. (None of the latter needed in very soft water areas, maximum in very hard water areas)

Cheers,

R.

 

[Tom Hoskinson]

I prefer a home made Wash Aid mixture of Sodium Sulfite, Sodium Bisulfite and Water.

Anchell and Troop published a concentrated recipe on page 105 of The Film Developing Cookbook.

Water at 125F/52C 750ml
Sodium Sulfite (anhydrous) 200 grams
Sodium Bisulfite 15 grams
Cold water to make 1 liter

Dilute 1:10 with water to make a working solution.

 

[dancqu]

Since I mix my own developer and fixer, it is the next step
to make my own HCA, but the formulations are a puzzle.

Agfa's recommendation for many many years was a 2%
solution of sodium carbonate. I've done preliminary testing
of sodium bicarbonate. Sodium bicarbonate is a very mild
alkali. The results were very encouraging. Over any
sulfite based clearing agent the two carbonates
have the advantage. They do not oxidize. Dan

 

[Ryuji]

Dan, as I said in another thread, sulfite is superior to bicarbonate as a washing aid and bicarbonate shouldn't be used in place of sulfite. Bicarbonate is ineffective in removing insoluble silver-thiosulfate complex ions that are just as damaging to the image as the thiosulfate. To remove this, you have to make sure the fixer is not over used and the material is treated in sulfite washing aid.

 

[Photo Engineer]

I have never used a wash aid either in work at Cape Canaveral or any of the work at Kodak. I don't use one personally. Washing is fine with me.

You still have the sulfite to wash out or whatever else you may use. Even if it takes less time, it is yet another chemical to use, store and dispose of.

PE

 

[dancqu]

...insoluble silver-thiosulfate complex ions ...
To remove this, you have to make sure
the fixer is not over used ...

I think the above says it all; ... "make sure the fixer is
not over used." I make sure by using the ST-1 test. That
test is done upon the paper itself. The ST-1 test is a sulfide
for silver test and a very easy one for home darkroom workers.
Ilford recommends the ST-1 test quite regularly in their
paper and fixer PDFs.

The ions you speak of are the argentous monothiosulfate
ions. The di and tri form are soluble. Dan

 

[Photo Engineer]

Dan;

Right on. That is the perfect test.

I use that along with the retained hypo test and the fixer exhaustion test.

Three standard solutions in my DR. Silver Nitrate in acetic acid, KI in water, and Sodium Sulfide. All are used for tests.

PE

 

[Ryuji]

I think the above says it all; ... "make sure the fixer is
not over used." I make sure by using the ST-1 test. That
test is done upon the paper itself. The ST-1 test is a sulfide
for silver test and a very easy one for home darkroom workers.
Ilford recommends the ST-1 test quite regularly in their
paper and fixer PDFs.

While ST-1 test is useful in testing for unfixed silver salts, it is not necessarily sensitive enough for residual silver-thiosulfate complex. However, the better news is that, in my experiments and actual darkroom practice, routine use of ST-1 is not necessary, as long as the instructions for fixer and washing aid are carefully followed.

ST-1 is also unnecessary if the printer routinely tones the prints in sulfiding or selenium toner.

The ions you speak of are the argentous monothiosulfate
ions. The di and tri form are soluble. Dan

Not necessarily. You are probably referring to old literature or material written by not-so-quite updated authors (including some of my very old postings) but there are other insoluble complex salts besides argentomonothiosulfate. Some of them were already known in 1960s. Either way, all of them are bad and all of them should be washed out by proper use of non-exhausted fixer and sulfite washing aid.

 

[Photo Engineer]

The phase rule of silver complexation with thiosulfate ion includes the possibility of at least 6 silver compounds, if not more, and as many as 3 or more sodium salts of thiosulfate existing in solution or as solid materials (less soluable).

When ammonia is added, this number escalates dramatically due to the inclusion of the ammonium ion in the complexes that can form.

Fixing is one of the more complex chemical reactions in photography, but one of the easier to design working solutions for.

The tests described above work well enough to yield prints which keep well under a wide variety of conditions with no need for worry and no need for additional post fixation rinse solutions.

However, there are some interesting properties of fixation that have never been discussed outside of reports at EK that I know of, nor have many of the novel fixing agents that have been described in the literature been used even though they are quite useful.

From a practical standpoint, all of the technobabble aside, the use of a given fix packaged by a reputable manufacturer and the use of their published methodology will give exellent stability, archival for all practical purposes as evidenced by prints lasting for 100+ years. For even longer life, if desired, a selenium bath will top things off. Anything else is wasteful of time, energy and money.

Those old prints in your family album from 50+ years ago were not treated in clearing baths and etc....

PE