What is the difference between Ammonium and Potassium Persulfate?

[Rlibersky]

I have found 2 different formulas for Nelson Gold Toner. One uses Ammonium Persulfate the other Potassium Persulfate. With a quick look at Photographers Formulary the price difference is ~$2 less for the Ammonium.

For toning purposes does it matter which one is used?

Thanks
Randy

 

[Nicholas Lindan]

Ammonium Persulfate ... Potassium Persulfate ... does it matter

I have no idea, but to add an extra monkey to the island, there is also sodium persulfate, normally the cheapest of the trio.

 

[Ian Grant]

Walter C Nelson's Gold Toner can be found in United States Patent US1849245, the Eastman Kodak formula can also be found in Agfa Ansco Formulae books in the 30's citing his Patent no.

The correct formula uses Ammonium Persulphate. There's likely to be advantages using the ammonium salt over the potassium or sodium salt, the toner should be slightly faster acting.

Ian

 

[nworth]

I have also seen potassium persulfate (also at 30 g/l) prescribed. It may not make much difference, but the original recipe calls for ammonium persulfate.

 

[dancqu]

I have found 2 different formulas for Nelson Gold Toner.
One uses Ammonium Persulfate the other Potassium Persulfate.
With a quick look at Photographers Formulary the price difference
is ~$2 less for the Ammonium.

For toning purposes does it matter which one is used? Randy

It matters not. Nelson's is essentially a sulfide toner.
The minute amount of gold used in toning a print modifies
the structure of the sulfur laid down. Prints do not look as
though they are sulfided.

Either persulfate is a very strong oxidizer. It is used to
precondition the thiosulfate so that on use the thiosulfate
will disintegrate and lay down sulfur. See Hypo Alum toners
for comparitive purposes. Nelson's is a hypo alum toner
without the alum but adds a pinch of gold. I'm of the
opinion that the gold acts catalytically allowing for
lower temperture toning.

Today's sodium thiosulfate may not need nearly as much
of the persulfate. Nelson's formula dates from the 30s.
Also the anhydrous will do just as well. Reduce
amount by one third and save $$$. Dan

 

[Ian Grant]

When you change the salts used in a toner there's an impact on the image colour formed. In developers using sodium, potassium or ammonium, carbonates affects the warmth of the developer.

So Potassium Persulphate is not a direct replacement for Ammonium Persulphate and with some papers the difference in tones produced is likely to be quite noticeable.

Ian

 

[gainer]

Ammonium Persulfate is also used as an etchant in making printed circuit boards. It is slower than ferric chloride unless it is heated, but for that purpose has the advantage that one can see through it.

 

[dancqu]

When you change the salts used in a toner there's an
impact on the image colour formed. In developers using
sodium, potassium or ammonium, carbonates affects the
warmth of the developer.

So Potassium Persulphate is not a direct replacement for
Ammonium Persulphate and with some papers the difference
in tones produced is likely to be quite noticeable. Ian

Perhaps so. As a salt gold chloride does wonders. How
about a pinch of ... ? I did overlook various salts image tone
effects. Also I overlooked potassium's potential for poisening
an essentialy 'hypo' type sulfide toner.

Although never made clear the potassium salts of the silver
thiosulfate complex and/or the thiosulfate itself are only
slightly soluble; the complex IMO. B. Troop has warned
against allowing ANY potassium to enter into the fixer.
Apparently though some little is OK.

For the OP: I suggest adding that persulfate slowly and
only enough to ensure the sulfurization of the mix. Dan