For TF-4 Users.

[Joe Mace]

TF-4 is alkaline and Ilford Rapid is acidic.

As for alkaline vs acidic fix, there are long discussions in here on that. Basically, it's easier to wash the fix and its by-products out of fiber paper if the fix is alkaline.

By the way, welcome to APUG from another New Hampshire-ite!

I just re-read my Rapid Fixer lit and I see that it is indeed acidic -- pH 5.5 or so. Thanks for clearing that up.

I'm initiating my use of Pyrocat-MC this weekend on some FP4+ 4x5s I shot last week up near Lake Umbagog (Errol, NH). I've been using D-76 up to now. I'm assuming there will be no problem in continuing to fix the film with Ilford Rapid Fixer.

It sounds, however, like should consider using TF-4 when printing on FB (Lodima).

Thanks for the warm welcome.

Joe

 

[Photo Engineer]

Huh? I thought TF-5 was perfect. I'm crushed!!
Next you'll tell me I should re-think dumping Hypam for TF-5...

TF-5 is identical to TF-4 except for the items above.

I have worked out a premium fixer based on Super Universal Fix in the Articles section of APUG that does better for wash times. It uses a gelatin swelling agent to promote wash rates.

PE

 

[L Gebhardt]

Before the arrival of TF-5 I switched to C-41 fixer from TF-4 for paper because of the smell. How does TF-5 compare to C-41 fixer. Both are slightly acidic ammonium thiosultafe fixers. Will one wash better than the other? Any reason to choose TF-5?

Also, how do you test fixer capacity? The TF-5 directions mention we should test our own capacity, but no direction is given.

 

[Photo Engineer]

The choice is for you to make. Make it on price and convenience.

The test is based on those presented here in posts. There is the retained hypo test for washing, the retained silver test for fixing and the silver exhaustion test for the fixer which is the weakest of all tests. I have given details on these here and test solutions are available from most companies.

Due to wash water variations, it is difficult to establish a "true" wash rate. That is why the instructions suggest testing wash rates to your satisfaction.

PE

 

[jgjbowen]

I just re-read my Rapid Fixer lit and I see that it is indeed acidic -- pH 5.5 or so. Thanks for clearing that up.

I'm initiating my use of Pyrocat-MC this weekend on some FP4+ 4x5s I shot last week up near Lake Umbagog (Errol, NH). I've been using D-76 up to now. I'm assuming there will be no problem in continuing to fix the film with Ilford Rapid Fixer.

It sounds, however, like should consider using TF-4 when printing on FB (Lodima).

Thanks for the warm welcome.

Joe

Joe,

You should use an alkaline fix with pyro negatives. I use TF-4 with Pyrocat HD negatives. I believe the acid fixes have a negative (pun) impact on the pyro stain.

 

[dancqu]

What of the Water?

Basically, it's easier to wash the fix and its by-products
out of fiber paper if the fix is alkaline.

But it is the water which washes. Acid or alkaline any
FB paper soon after immersion takes on the ph of
the water. Perhaps it is the water which should
be alkaline. Dan

 

[Joe Mace]

Joe,

You should use an alkaline fix with pyro negatives. I use TF-4 with Pyrocat HD negatives. I believe the acid fixes have a negative (pun) impact on the pyro stain.

I appreciate your advice. Just ordered some TF-5 from Photographers Formulary. (It's on sale!!) Will wait until it arrives to begin developing with Pyrocat.

Joe

 

[Photo Engineer]

But it is the water which washes. Acid or alkaline any
FB paper soon after immersion takes on the ph of
the water. Perhaps it is the water which should
be alkaline. Dan

The water doing the washing starts out with a gelatin that is more swollen the more alkaline the fix. Therefore, as wash proceeds, the gelatin will begin to shrink, but very slowly. A similar condition holds in that the sized FB papers will hold onto the complexes less tightly if the paper is more alkaline. The excess ammonium ion helps with release from the paper stock.

So, your comment does not take into account the d(pH) / dt or the change in pH vs time.

PE

 

[Tim Gray]

A point was made earlier about longevity of the stock fixer solution and the longevity of the dilute fixer. I have partly full bottles of the TF-5 stock on the shelf that are up to 5 years old and still good. I have kept it in the tray for about 6 months used one time.

I'm confused. I thought TF-5 was a new product. But you've been using it for 5 years. Typo or did you have a hand in developing it?

 

[Photo Engineer]

I had a hand in developing it!

I started work on a series of fix baths over 5 years ago and that statement is the result of having old batches of TF-5 here for several years.

So, to you new, to me.... old!

PE

 

[Tim Gray]

Ahh ok. And Superfix is next, right?

 

[Ray Rogers]

The water doing the washing starts out with a gelatin that is more swollen the more alkaline the fix. Therefore, as wash proceeds, the gelatin will begin to shrink, but very slowly.

So, your comment does not take into account the d(pH) / dt or the change in pH vs time.

PE

How slowly?

Actually, it seems you switched between swell and pH here, but as for pH...

How slowly?

If you add an acid or an alkali to a gelatine solution it changes pH rather quickly doesn't it? Since we are talking about rapid fixers, there is isn't a whole heck of a lot of time for them to do their job if the change in pH is that slow anyway...

I think Dan is correct and the wash water pH is important... I can't see any reason why it should not be even more important than the fix pH.

(unless more insoluble complexes are being formed at one pH than another.)

And as for swell,

How slowly?

Swell may well proceede at a dif rate than shrink (I don't recall)
but that is the point isn't it? What are the swell and shrink rates at dif. pHs

Ray

 

[Photo Engineer]

Ray;

Swell change is dependant on wash water, but the fix overwhelms the wash water at the first instant of contact with a gradual change over time due to the change in buffer capacity. Wash water has no buffer capacity so Dan is not correct if one is comparing it to the fix.

Fix complexes change as the solution becomes more dilute. Mees and James describe some of the various complexes that silver ion forms with hypo. These are formed due to concentration changes and they diffuse differently and have different solubilities.

Swell and shrink do proceed at different rates, but then one must consider that each expansion and contraction of gelatin changes its elasticity. This is in-effect, denaturing the gelatin. I cannot predict that either.

PE

 

[dancqu]

Actually, it seems you switched between swell and pH here,
but as for pH...

I think Dan is correct and the wash water pH is important...
I can't see any reason why it should not be even more
important than the fix pH.

First of all I'm neither correct nor incorrect. My earlier
post "What of the Water" did no more than suggest
that an alkaline wash might be appropriate.

From my vantage point dwelling upon swell is beside
the point. We all know that it is the fiber and baryta
coating which have a tenacious grip upon the silver
thiosulfate complexes. That given what part does
swell play?

The preponderance of the OH ion in an alkaline fix
substitutes the OH ion for the silver thiosulfate ion.
What other mechanism could be at work? Consider,
for most using FB paper the first 'wash' after fix is
an alkaline hypo clearing agent. Dan

 

[Photo Engineer]

The preponderance of OH ion in an alkaline fix actually is irrelevant except as it effects pH and thus swell. It is the NH3 ion which changes the picture more than anything else by placing at least one NH3 into the cage complex replacing at least one Thiosulfate. This changes both the size of the complex and the charge on the complex. The OH is merely the counter ion and does not enter into complexation at all.

The size change effected by the substitution, coupled with the swell increase will cause a substantial increase in wash rate at an alkaline pH. If one finds a "sweet spot" in pH that allows multiple NH3 ions to enter the cage, then the complelx becomes even smaller and will thus diffuse more readily.

If one adds to this additional swell enhancing agents then the gelatin becomes even more swollen and allows even more rapid washing.

In all cases, the wash rate of film can be decreased as well as the wash rate of RC papers, but the wash rate of FB is decreased by less. The Baryta holds on to the complexes quite strongly and the sized papers hold on to them but less strongly. Film and RC support do not hold on to the complexes at all.

PE

 

[dancqu]

[QUOTES=Photo Engineer;867670]
"The OH is merely the counter ion and does not enter into
complexation at all."

Agreed.

"The size change effected by the substitution, coupled with the
swell increase will cause a substantial increase in wash rate
at an alkaline pH."

an "...increase in wash rate at an alkaline pH." Again, agreed.

"If one adds to this additional swell enhancing agents then the
gelatin becomes even more swollen and allows even
more rapid washing."

The emulsion, now even sooner to come clean.

"The Baryta holds on to the complexes quite strongly and the
sized papers hold on to them but less strongly."

Well, I don't see much disagreement although I'm not much
sold on NH3's being any help. In the presence of any of the
halides of silver it has little relative affinity and the less as
one progresses from chloride to iodide. The thiosulfate ion
has greater affinity through the series. As long as there
be free thiosulfate it will gather silver to itself. Dan

 

[Ray Rogers]

I'm not much sold on NH3's being any help.
In the presence of any of the halides of silver it has little relative affinity...

Nevertheless, it will have enough to increase the solubilty of AgX in a dilute solution of the halide.

 

[Kirk Keyes]

Joe,

You should use an alkaline fix with pyro negatives. I use TF-4 with Pyrocat HD negatives. I believe the acid fixes have a negative (pun) impact on the pyro stain.

Have you tested that yourself? I have, and I find no significant difference between stop bath with water bath when using pyro developers.

 

[jgjbowen]

Kirk,

I don't use a stop bath between Pyrocat HD and TF-4; so no, I haven't tested it myself. The use of an alkaline fix for Pyro negatives is something I read. I likely read it in one of Sandy King's articles, the Pyrocat HD instructions, one of Steve Ancell's books or the Book of Pyro. I honestly don't remember where I read it. However, 5 - 10 minutes in an acid fix will have a much greater stain impact then 30 seconds in a mildly acidic stop bath.

Do you use an acid Fix with your pyro negatives?

 

[Photo Engineer]

Just a comment on Ammonium Ion in fixes.

Ammonium Ion can replace Thiosulfate Ion in the cage complex around Silver Ion being dissolved. Ammonium is much smaller than Thiosulfate, very much so, and this size difference adds up to a diffusion difference. The added affinity tends to cause a synergy between Ammonium and Thiosulfate such that together they become "rapid fixers". Does that sound familiar? So, together, at the right pH, they become promoters of rapid washing as well.

In an Ammonium Thiosulfate fix, you can get a dozen or more complexes form, not just the 5 or 6 shown by Mees and James for Sodium Thiosulfate. And, all of these are smaller and of lower molecular weight than the corresponding Sodium complexes. Among other things, the Ammonium ion becomes the cation for the complex and an extra cation is thus not being dragged along as is the case with Sodium which is inert to the complexation reaction, just a drag on diffusion.

You see, I've said before that fixation is not simple. It is as complex as development but has not been studied much nor is much known about it in the "outside world". For an example, see the Super Fix formula in the articles section here on APUG. It embodies other reactions that are often ignored.

PE

 

[dancqu]

Nevertheless, it will have enough to increase the solubility
of AgX in a dilute solution of the halide.

The ammonium ion will complex with silver and do it in the
presence of the halides. With only the chloride present it can
even act as the sole fix agent. Beyond that, bromide and iodide,
something with a greater affinity is needed. So, thiosulfate.

Thiosulfate has such a great affinity for silver that it will strip
the silver from it's extremely insoluble iodide and even sulfide.

In a rapid fix it also strips the silver from any silver ammonium
complexes present. As I've said the thiosulfate ion gathers to
itself the silver. In a word the ammonium ion acts as an
intermediary bringing into solution by complexing with
any silver for which it has great enough affinity. As
Ron has said they work synergistically. So, Rapid.

Rapid save for iodized emulsions in which case silver
is not complexed to any meaningful extent by the
ammonium ion. Rapid fixers become Slow with
much reduced capacity. Dan

 

[Photo Engineer]

Thiosulfate cannot complex with Silver Sulfide. The Silver-Sulfur solubilty product is at least an order of magnitude stronger than the Silver-Thiosulfate complexation constant.

The synergy between Thiosulfate and Ammonium ion is stronger than with Iodide, but not by much. If sodium is present, the reaction is much slower. Therefore, you do see Ammonium fixers being rapid when compared with Sodium fixers. The best comparison is with a Potassium fix which works not very well at all.

In fact, Iodide can accelerate fixation in some cases as outlined in our patent which shows that Iodide can be added to rapid fixers and rapid blixes to get even more rapid reaction rates, which is counter intuitive but I assure you that it works. Just don't try it at home. If you don't know how to do it, it won't work!

PE

 

[Kirk Keyes]

I don't use a stop bath between Pyrocat HD and TF-4; so no, I haven't tested it myself. The use of an alkaline fix for Pyro negatives is something I read. I likely read it in one of Sandy King's articles, the Pyrocat HD instructions, one of Steve Ancell's books or the Book of Pyro. I honestly don't remember where I read it. However, 5 - 10 minutes in an acid fix will have a much greater stain impact then 30 seconds in a mildly acidic stop bath.

Do you use an acid Fix with your pyro negatives?

I use a rapid fixer, either Ilford Hypam or Kodak Rapid Fixer (without hardener) or Kodak C-41 fix. They are all weakly acidic - with a pH of about 5.5 or so. Not what I would term an "acid fix" as they are very close to neutral pH.

(Note: I have played with TF-4, TF-5, and the upcoming Super Universal Fix. I never liked the precipitate/sludge aspect of TF-4, but TF-5 and SUF are both precipitate free and I'll take some more consideration of them in the near future.)

What's your definition of a "mildly acidic stop bath" and what is it's pH? I think you'll find that if you are using a rapid-type fixer, the stop bath is more than 100 times more acidic than the fixer is.

Most stops are going to be less than pH 3 when fresh and the pH slowly increases as the acid gets used up. So a used stop bath will be around pH 4 for much of it's usefull life.

That's a much lower pH and much more acidic than any rapid fixer.

The test I did was comparing fresh acetic acid stop bath (so the pH was about 3 as I stated above) with a running water stop bath. As I said in the earlier post, the difference I saw was slight between the two tests (I used PMK as my staining developer).

There was a slight difference in the overall density of the two films - the water bath film did have a slightly higher density, about 0.02 OD than the stop bath. One may wish to claim it was due to the acid stop lowering the stop bath film density, but I suspect it was due to the water bath film continuing development and not being stopped immediately like the stop bath film was. The difference was so slight, I did not pursue it further and continued to use stop bath.

(Other note: I use a buffered stop bath. I make a strongly acidic acetic acid stop bath, and then I add sodium acetate which buffers the stop. If raises the pH up to about pH 5, while increasing the acidity of the stop bath. It makes for a very fast acting stop bath but with a much milder pH. Keep in mind that acidity and pH are not the same thing.)

 

[Keith Pitman]

Photographers' Forumulary usually has free shipping in December. I buy enough for the next year.

I just don't like paying to ship the water.

Mike

 

[mikebarger]

Thanks, I didn't know that!

Mike