Fixer precipitates part 2

reub2000 · Feb 28, 2007

I switched to TF-4, from Kodak Rapid Fixer hoping to cure my precipitate problems. Last friday, I fixed 2 rolls of tri-x, which came out great with no precipitate. Then on sunday, I fixed a roll of delta 100, which came out with a lot of white dots. To make sure it wasn't a fluke, I took a strip of unexposed tri-x, fixed it, washed it, and the dried it. Scanned it, and it has many dots. Where are these coming from? Is the 1 gallon plastic container the wrong kind of container for fixer?

Neil Miller · Feb 28, 2007

Ive had distilled water in plastic cans exhibit this problem before - I think something must have been left in the plastic can from the manufacturing process before the water went in.

In any case, filtering it out into another container solved the problem.

Incidentally, I got a number of small plastic cans of fixer (from Nova) that were absolutely full of glittery specks of suspended material - filtering solved this, too.

Regards,
Neil.

FrankB · Feb 28, 2007

Do you live in a hard water area?

I've had symptoms like this and cured it by putting all my film processing and washing water through a Britta jug filter.

All the best,

Frank

reub2000 · Feb 28, 2007

FrankB said:
Do you live in a hard water area?

I've had symptoms like this and cured it by putting all my film processing and washing water through a Britta jug filter.

All the best,

Frank

I don't know. My water comes from Lake Michigan. The water does seem to be a bit milky when it comes out of the faucet, but it very quickly becomes clear.

FrankB · Feb 28, 2007

The milkiness could be lots of things. I believe you can get kits for testing water hardness from most large supermarkets (quite often for free). The jug filter idea may or may not be of use, but it's one more thing to try. If you can beg or borrow one then I'd give it a shot.

My workflow is to fill the sink with water at 20C, put it through the jug filter and then mix with the neat chems to working strengths (I used Ilford and Paterson liquid chems). I store the remainder of the filtered water in a big jug for washing (using the Ilford method).

It is a bit time-consuming, but for me it works. I hope you find something that works for you.

All the best,

Frank

Neal · Feb 28, 2007

Dear reub2000,

Try using distilled water for mixing your chemicals. Maybe you'll get lucky.

Neal Wydra

Lee Shively · Feb 28, 2007

If the milkiness quickly disappears it's probably just air bubbles. I've used the basic plastic Delta jugs for Kodak Rapid Fix with no problems. Maybe you should try a new jug for the fixer, rinsing it clean each time you mix new chemicals.

dancqu · Feb 28, 2007

reub2000 said:
To make sure it wasn't a fluke, I took a strip
of unexposed tri-x, fixed it, washed it, and the
dried it. Scanned it, and it has many dots.

Fixed and WASHED. The sodium and ammonium salts of
the silver thiosulfate complexes are soluble. The potassium
somewhat less so. It is reasonable to believe that impurities in
the fixer and wash water are leading to precipitation within
the emulsion of insoluble silver thiosulfate complexes.

Your first two rolls were OK. Fresh fixer free of silver
thiosulfate complexes was used. Why chance it? Use
distilled start to scratch. Dan

reub2000 · Mar 1, 2007

dancqu said:
Fixed and WASHED. The sodium and ammonium salts of
the silver thiosulfate complexes are soluble. The potassium
somewhat less so. It is reasonable to believe that impurities in
the fixer and wash water are leading to precipitation within
the emulsion of insoluble silver thiosulfate complexes.

Your first two rolls were OK. Fresh fixer free of silver
thiosulfate complexes was used. Why chance it? Use
distilled start to scratch. Dan

Not sure I really understand. I guess I should order another litre of TF-4 fixer, and mix it with 3L of distilled water.

Also, would it be better to use the fixer one shot? It seems like it would last longer? Or is that just a stupid idea?

Edit: Could my use of a stop bath have caused this?

dancqu · Mar 1, 2007

[QUOTES=reub2000;437402]
"Not sure I really understand."

Fixer is used to remove from the emulsion all remaining
non-image silver chloride, bromide, and iodide if any.

The halogens mentioned are insoluble in water but the
thiosulfate within a fixer solution will attach to the silver
atoms and render those halogens soluble. In effect the
silver chloride, bromide, or iodide, dissolves.

The compound, in ionic form when in solution, becomes
sodium or ammonium argentous thiosulfate; Soluble. Were
calcium or magnesium or iron or... also in solution they
may form compounds with the argentous thiosulfate,
ie calcium argentous thiosulfate; Insoluble. Dan

Photo Engineer · Mar 1, 2007

Technically Dan, there is no such thing as argentous salts as there is no argentic salt, at least in English chemistry texts, so the rendition of an oxidation state is deemed redundundundundant. It is ammonium silver thiosulfate or more properly sodium monoargento monothiosulfate and all of the associated complexes (there are at least 4 that form). So much for nits.

Now for the nitty gritty. If Calcium, Magnisium or Potassium are present, and form salts with silver and hypo, they don't form specs, they merely represss the dissolution of silver into the hypo bath and leave behind silver salts in the coating.

If a fix is overused and exhausted, then these metals can cause a fine precipitate of white or gray silver salts.

I believe that this may be calcium hydroxide forming in the alkaline fix if the water is very hard. But, that is a reach as I have never seen it happen and the fix is well buffered and not very alkaline.

It could be sulfur forming on the sides of the container or left behind from a previous batch of fixer. I have seen that when a container that contained fixer that was old was reused for fresh fixer.

In any event, filtering the fixer through a paper coffee filter would probably fix this up just fine.

PE

zenrhino · Mar 2, 2007

PE, I just had the same thing happen (got a precipitate of streaky grey/white particles) only my fixer had also turned dark grey. I did a test and film cleared in less than 2 minutes so I didn't think the fixer would be exhausted. We do have pretty hard water up here (300ppm give or take, mostly carbonate -- chalk and gypsum from the limestone).

Photo Engineer · Mar 2, 2007

Alkaline fixers would be more prone to form insoluable hydroxide salts of the calcium and magnesium present in hard water. Use of distilled water or simple filtration through a paper coffee filter will usually solve the problem.

PE

dancqu · Mar 2, 2007

dancqu said:
Fixer is used to remove from the emulsion all remaining
non-image silver chloride, bromide, and iodide if any.

The halides mentioned are insoluble in water but the
thiosulfate within a fixer solution will attach to the silver
atoms and render those halides soluble. In effect the
silver chloride, bromide, or iodide, dissolves.

The compound, in ionic form when in solution, becomes
sodium or ammonium argentous thiosulfate; Soluble. Were
calcium or magnesium or iron or... also in solution they
may form compounds with the argentous thiosulfate,
ie calcium argentous thiosulfate; Insoluble. Dan

I've substituted halides for halogens in the above post.
The halogens are fluorine, chlorine, bromine, and iodine.
The halides are some combination of other elements
with those halogens; eg NaCl is a halide of sodium
as is AgBr a halide of silver. Dan

Photo Engineer · Mar 2, 2007

Dan, the word "argentous" has no meaning. It is "argento" or just plain "silver". I hate to pick nits, but I want the readers to get their chemistry correct so we all are talking on the same, correct, page.

My sincere apologies for this though.

PE

dancqu · Mar 3, 2007

[QUOTES=Photo Engineer;438164]
"Dan, the word "argentous" has no meaning."

Perhaps for some it has no meaning. For others
the thousands of entries available via Google for
both argentous and argentic have some meaning.
An "in English" text I've at hand does mention
argentous in connection with thiosulfate.

"It is "argento" or just plain "silver".

Argentum, Latin - Argento, Italian - Silver, English.
So "argento" or just plain "silver". Elemental silver.
Another text, Pauling's, mentions only silver.
Then again he does not discuss it's three
possible valences. Dan

PhotoJim · Mar 3, 2007

"Argentous" is in my dictionary. "Pertaining to silver".

Photo Engineer · Mar 3, 2007

Ok, Mees in the chapter on fixing uses Argento or Silver exclusively to describe silver salts and silver complexes.

I have looked in two chemical dictionaries, and one has no Argent- with any suffix listed, while in another it lists 'Argentous and Argentic - see Silver' in the heading of the chemical tables.

The chemistry texts I have state that the suffix 'ous' is used for salts in the lower oxidation state and the suffix 'ic' is used for salts in the higher oxidation state when there are two oxidation states, as in cuprous and cupric, or ferrous and ferric.

If there are more than two, then the lower two use these two suffixes, but the additional states are designated by the numeric state of oxidation.

If there is one oxidation state, then no suffix is used.

Therefore, the use of Argentous or Argentic implies two possible oxidation states. In addition, since the word is an adjective, there is only one real meaning such as "an argentic sheen" or a sheen pertaining to silver. Cuprous has two meanings though, as in cuprous chloride or "the stormy sky looked cuprous".

That is the best I can say regarding usage in current English language chemical texts. Argentous is a word, an adjective, but is not used in chemical terminology at the current time as far as I can find.

Lets use Natrium and Kalium and Wolfram too while we are at it.

PE

reub2000 · Mar 4, 2007

Seriously Ron, does this argument have any point?

The water mark on the film in the second example is probably also from the hardness of the water, right? Mixing the photoflo using purified water would probably help, right?

Photo Engineer · Mar 4, 2007

Yep, or filtering fixer that already has the precipitate. That would be usable.

The rest was all meant in fun, but also to be correct in chemical nomenclature. There are too many errors floating around on the internet. But in any event, I apologize.

PE

dancqu · Mar 4, 2007

[QUOTES=Photo Engineer;438532]
"Ok, Mees in the chapter on fixing uses Argento or Silver
exclusively to describe silver salts and silver complexes."

So too L. Pauling as I pointed out. Were there any doubts
as to the valence of the silver, argento, then Mees likely
would have specified the argentous. We into darkroom
chemistry are only concerned with the argentous.
That being specific.

"Argentous is a word, an adjective, but is not used
in chemical terminology at the current time as far as
I can find."

You'll find Argentum up to ++++ via Google. Dan

Photo Engineer · Mar 4, 2007

Dan;

I fully appreciate what you said. I don't see any prior reference here to Linus Pauling. BTW, I used his text in my first year at college.

Argentum is the correct name for silver in its metallic form. This is why we use Ag for the symbol. It is like using Wolfram for Tungsten and etc. You can correctly say Argenum chloride and it equates with silver chloride. Argentic is not correct at all and Argentous is usable but an oxymoron or redundant.

PE

dancqu · Mar 4, 2007

[QUOTES=Photo Engineer;438810]
"Dan; I don't see any prior reference here to Linus Pauling."

Two posts back.

"Argentic is not correct at all and Argentous is usable
but an oxymoron or redundant."

I'll not argue but do know better; I've gone Google. Dan

Photo Engineer · Mar 4, 2007

Dan;

My copy of Pauling mentions only one oxidation state. Merck and the Chemical Handbook only offer one oxidation state, but Moeller, "Inorganic Chemistry" does indeed list Ag+2 and Ag+3 stating that the formation of Ag+2 is only found at a concentration of 10^-17, or 1 x 10 with 17 zeroes in front of it and a decimal, and is made only in concentrated nitric acid and ozone.

It is a powerful oxidant. Moeller does not say how one obtains Ag+3.

It is possible to make compounds of intert gasses and we refer to them in the industry more commonly than higher oxidation states of silver. Three out of 4 of my texts don't even mention it. I have never seen or heard of a single stable salt of silver other than +1 state and Moeller does say that. That oxidation states higher than 1 are unstable.

It is nothing more than a lab curiosity, and nomenclature does not 'normally' use it. You may if you wish, but its use here in photographic terms is useless unless you wish to confuse people with using names no one uses commonly. If Google references use those names as common terminology, they are wrong as are many references. BTW. Moeller does not use "ous" and "ic" nomenclature for them. They are uncommon enough that he refers to them as Ag III or Ag II or by other means rather than the uncommon suffixes.

You must be an attorney.

PE

dancqu · Mar 4, 2007

[QUOTES=reub2000;437402]
"Also, would it be better to use the fixer
one shot? It seems like it would last longer?
Or is that just a stupid idea?"

I thought some other might answer that question
as I'm not the only APUGer who uses film fix one-shot.
Fresh fix each roll or rolls and at least 34 for sure rolls
per liter of concentrate. The concentrate if split into
smaller well capped bottles will last longer. I've all
my chemistry in glass Boston Rounds. Were I still
using rapid fix a liter of concentrate would first
be split to 4, 1/4 liters and one of those split
again for convenience of use.
.

Any rapid fix should be good for that many rolls.
They likely vary some in strength so to be sure
do some tests. For starters allow 10 minutes;
continuous agitation the first minute then
a few inversions each minute. Less time
may do but will take some testing.

"Could my use of a stop bath have caused this?"

Not likely. Those spots are within the emulsion? Not
on the surface? If so, IMO, it is as I first mentioned,
precipitation within the emulsion. Dan

Fixer precipitates part 2

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