Alkali fixers and HT-2

Tom Kershaw · Aug 8, 2008

I intend to use an alkali fixer (Fotospeed FX40) when printing fibre base paper. Ilford Hypam and FX40 both use Ammonium Thiosulphate but I'm concerned that the HT-2 (to test for residual fixer) solution may work differently when applied to a print that has been in an alkali fix rather than an acidic fix before washing. Any ideas?

Tom.

Edit: According to Fotospeed the solution is testing for remaining acid not remaining Ammonium Thiosulphate.

Ian Grant · Aug 8, 2008

As many fixers are only very mildly acidic, pH 5 -5.5 Ilford Hypam / Ilford Rapid Fixer, I can't see how the Fotospeed HT-2 could test for remaining acid, particularly if a wash aid containing Sodium Sulphite or carbonate is used after fixing. Most test are for residual silver.

The usual problem with fixers for FB papers is incomplete fixation leaving insoluble silver complexes which later react with light causing staining of the prints, this is overcome by using two bath fixation.

Ian

Tom Kershaw · Aug 8, 2008

Ian,

I thought that Alkali fixers didn't need an HCA before washing prior to toning? i.e. dev - stop - fix 1 - fix 2 - wash; realising HCA is needed after selenium toning.

Perhaps I am being overly concerned. In 'The Photographer's Toning Book' Tim Rudman suggests using a 10% solution of Selenium Toner to test for residual silver. My proposed process involves 2 bath fixing, HCA, toning etc. according to Rudman.

Tom

dancqu · Aug 8, 2008

Tom Kershaw said:
According to Fotospeed the solution is testing for remaining
acid not remaining Ammonium Thiosulphate.

Actually the silver nitrate FT-2 test is looking for sulfur.
It is a silver for sulfur test. An Ilford formula for the FT-2
test, IIRC, is nothing more than a 2% solution of silver
nitrate. I place the drop or drops on dry paper. Be
sure you examine for stain soon after testing
and do so in dim light. Dan

Ian Grant · Aug 8, 2008

A couple of things can aid fixing/washing, a citric acid/sodium citrate stop bath helps and I'd always use a wash aid regardless of the pH of the fixer.

Your proposed process is standard for archival printing.

Ian

Ian Grant · Aug 8, 2008

Now I've found the formula - HT-2 is testing for residual Thiosuphate, not acid so will definitely work with any acid, neutral or alkaline fixer.

Ian

Tom Kershaw · Aug 8, 2008

Now I've found the formula - HT-2 is testing for residual Thiosuphate, not acid so will definitely work with any acid, neutral or alkaline fixer.

Interesting, perhaps I wasn't sufficiently clear with Fotospeed.

Ian Grant · Aug 8, 2008

The Fotospeed Residual Hypo test should be similar to HT-2. A simpler test used to be to use a drop of fresh Potassium Permanganate solution any residual sulphite/metabisulphite/thiosulphate would clear the pink stain or cause a brown stain.

Ian

Photo Engineer · Aug 8, 2008

There are 2 tests that should be performed.

One uses Sodium Sulfide and is used to test for residual silver (incomplete fixing). It leaves a dark brown to black stain if silver salt is present. To a certain extent, it can also detect bad washing because it gives a positive test if silver thiosulfate complexes are present.

The second test uses acidic silver nitrate. It tests for hypo by turning brown in the presence of thiosulfate salt. There is a published color chart, which I posted on APUG, for this test.

Both work for all types of fixes except those which do not use thiosulfate at all.

PE

Ian Grant · Aug 8, 2008

The second test Ron (PE) mentions is HT-2.

Ian

Photo Engineer · Aug 8, 2008

Yes, thanks Ian, an oversight on my part, as this was a significant piece of information that was needed. I guess I have not woken up yet. Sorry.

PE

Tom Kershaw · Aug 8, 2008

Ron,

Thank you very much for clearing up the situation.

Tom.

Kirk Keyes · Aug 8, 2008

Tom Kershaw said:
Edit: According to Fotospeed the solution is testing for remaining acid not remaining Ammonium Thiosulphate.

It looks like Fotospeed is incorrect. Dancqu right.

And since the paper should be washed before being tested, the pH of the paper will be fairly neutral. So the test will proceed as it was designed.

dancqu · Aug 9, 2008

Kirk Keyes said:
It looks like Fotospeed is incorrect. Dancqu right.

And since the paper should be washed before being tested, ...

I puzzled over the reason for the acetic acid; the Ilford
formula I mentioned earlier uses none. My with and without
testing indicates a slower response to and less of a response
to light if the solution is acidified. My guess, the nitrate is largely
converted to the acetate. The later is less sensitive to light.
What of a drop remains within the emulsion contains some
silver salt; stain or no. A light and environmentally
sensitive silver salt. Dan

Kirk Keyes · Aug 9, 2008

I think the acetic acid is a simple way to keep the pH of the nitrate solution on the acid side, so the nitrate stays in solution, and perhaps to liberate any sulfides?

The silver is neither nitrate nor acetate in solution. It is in ionic form and not as a salt.

Ian Grant · Aug 9, 2008

Just to clarify the OP is about HT-2

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.)

dancqu · Aug 9, 2008

Ian Grant said:
Just to clarify the OP is about HT-2
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.)

The Ilford formula is simply a 1% silver nitrate
solution. Ilford Manual of Photography, 5th
edition.

Some sources direct the washing away of
excess reagent. I test dry prints. After the
drop has remained 2 to 3 min I blot up with
tissue then examine using a low wattage
white light. Dan

Alkali fixers and HT-2

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