Troubles with thiourea and gold toning

[pau68]

Hello!

After reading Tim Rudman's book on toning, I have been experimenting with
thiourea and gold toning, and I have encountered some problems. I would
like to ask for counsel here in order to solve them, if possible.

The pictures below show perfectly the problems.
They were copied the same day, on Ilford MGWarmtone, developed with Ilford Warmtone developer, 1+9,
odourless stop bath, tetenal superfix 1+3 1m, rinsed during 5m, lavaquick during 5m and washed
during 30m in a washing processor. They may have slightly different grades and exposures.

The toning session was some days later. Each copy received a different treatment:

1. KRST + gold,
2. KRST + thiourea + gold,
3. KRST + thiourea,
4. thiourea.

The process was the following (some of the steps have been skipped if the corresponding
toner wasn't performed):

soaking in water, KRST, short wash, lavaquick, long wash, bleaching (ferri + potassium bromide,
1+29, different times), short wash to get rid of yellow stain, thiourea, long wash, gold, fixer, short wash, lavaquick, long wash.

My main concern is with picture number 2. You can see that the clouds in the sky are full of
irregularly distributed pink stains. These stains appeared during the gold toning after the thiourea.
I don't know were they came from. They do not appear if the thiourea is skipped (picture 1) or if
the gold is skipped (pictures 3 and 4) independently of the selenium step. I have two different guesses:

- not enough wash after the bleach (but, then, why that pattern?)
- the water is very hard (here in Barcelona), and when the print was left to dry, the drops
dried and made some invisible stain in the copy which, with the thiourea - which is a quite strong alcali,
with the hydroxide - and the gold, become visible.

In my next session I was going to perform a final rinse in deionized water after the wash, in the printing stage
and a deeper wash after the bleach. However, if someone has some ideas on the subject, please, enlighten me!

The second concern is visible in picture number 4. There are some deposits on the surface of the copy.
I think they are calcium deposits form the hard water wash after the thiourea step (which has a very high ph).
I was thinking about including an acid stop bath step between the thiourea and the wash in order to lower pH, but I could use some advice
here also!

I have included picture 1, where everything looks ok, for reference. Picture 3 has also some stains, similar to
those in picture 4.

Please forgive the long post. I will appreciate any advice.

Best regards,
Pau

 

[Bob Carnie]

You may not like my answer , but when prints stain in toners it usually or possibly a fixing problem.

Are you using a double fix routine with hypo clear bath then good wash with great replenishment of water on each print.

I use bleach sepia, gold and selenium, and your second image looks like what I would expect with the highlights picking up that peach colour.

When I am multiple toning as you are , I always wash well between toning steps, and make sure that each print is done.

but frankly this looks like a error in your initial sequence.


Bob

 

[Jim Noel]

I tend to agree with Bob. The stains are most likely from incomplete washing after the KRST.

Jim

 

[pau68]

Bob, Jim, thanks for your answers. I have also considered that
possibility. In fact, washing water was particularly cold that day, 11ºC
(around 52ºF), and then washing after KRST may have not been
enough.

However, if there had been fixer left in the print, wouldn't the stains appear
in the ferri bleach, regardless of the gold? But the stains only appear
with the gold toner - and before the last fixing bath -, and only after thiourea.
Besides the pictures in my post, I have a few other examples (processed in different days),
with the same pink spots, again, only if gold after thiourea was used.

Anyway, I will be more conservative with the washing step.

Thanks!

Pau

 

[Bob Carnie]

Yes if fixer was present as soon as the sepia,(after the bleach) is added then it would show then , but this is all I can add.

 

[Brook Hill]

I think you will find that Gold toning after thiourea goes pink then red and as thiorea tones the highlights first then they will go pink/red with the gold. The KRST will have affected the shadows first and stopped any thiourea toning in the shadows. In short the pink colour may not be staining but toning, thiourea plus gold equals pink/red

Tony

 

[Bob Carnie]

Yes the pink is the gold effect I see after sepia., blotchyness is the problem which I feel is improper fix time, strength, followed by too short of a wash or too cold of a wash.

I think you will find that Gold toning after thiourea goes pink then red and as thiorea tones the highlights first then they will go pink/red with the gold. The KRST will have affected the shadows first and stopped any thiourea toning in the shadows. In short the pink colour may not be staining but toning, thiourea plus gold equals pink/red

Tony

 

[Jim Noel]

52 deg F water is too cold to dissolve out the unwanted salts. Since washing is a soaking out process and not dependent on running water, a way around the problem would be to heat some water to between 70 and 80F, place the prints in and agitate for 2-3 minutes, then replace with more of the heated water. Five (5) exchanges of water should leave your prints pretty clean.

Jim

 

[pau68]

Hello, again,

I have an update on the problem, which is now solved.

The culprit was indeed the thiourea toning step, and, more
concretely, the tap water I used to prepare the working
solutions.

To check my hypothesis, I prepare eight identical copies, changing fixing time,
washing time and providing to half of them a final rinse of deionized water.
At least one of them was processed as I usually do.

Once they were ready, I toned them. But this time I used deionized
water to prepare the working solutions of the thiourea toning and
added an acid stop bath after the thiourea and before washing.

Finally, I toned all of them with gold, and none of the copies had problems!

I imagine that the problem was that the thiourea toning bath is very alkaline
(with a large amount of sodium hydroxide) and Barcelona's tap water is
very hard. Deionized water took care of the problem. For the same reason,
I included also the acid stop bath: in this way, when the copy reaches the
washing water, has a more or less neutral pH.

Anyway, the lesson here is that if one mixes her/his own chemicals, is better
to use deionized water for both stock and working solutions.

Thanks again to all!

 

[Bob Carnie]

Thank you for posting.

I found the water here in Toronto giving me issues when hypo clearing, by adding Sodium Hexametaphosphate to my mixture solved the problem immediately.

Thanks to the Guru Chemists here who quickly helped me .