KODAK T-8

[Philippe-Georges]

What is the exact CAS number of the polysulfide as needed in Kodak T-8 and in AFGA Viradon?
Is it the anion (= anorganic?) or the organic polysulfide I need?

 

[Philippe-Georges]

What confused me is this:

"Polysulfides are a class of chemical compounds containing chains of sulfur atoms. There are two main classes of polysulfides: anions and organic polysulfides. Anions have the general formula S2−n. These anions are the conjugate bases of the hydrogen polysulfides H2Sn. Organic polysulfides generally have the formulae RSnR, where R = alkyl or aryl..."

The credit for this quote is Wikipedia.

I Checked Wikipedia because the Sigma-Aldrich website, my main supplier for chemical compounds, shows several CAS numbers (and compound types):

• 68425-15-0
• 1313-82-2 (= Sodium Sulfide SNa2)
• 25212-74-2

I have to admit that this is the first time I try to mix a brown toner as my stock of Viradon is sadly used up...

 

[john_s]

I don't know much about this, but I have read that Na2S, plain sodium sulphide, is not suitable for some direct toner formulas. My understanding is that the relevant polysulphide is a mixture of sulphides of Na (or alternatively potassium) with not an exact formula inasmuch as the number of sulphur atoms is variable and more than 1.

I think that the CAS numbers that are compounds with CH and various other atoms are definitely not what you want.

 

[mohmad khatab]

This element is found in Egypt, and it is used in medical analysis laboratories,
I am a subscriber to a group of chemicals distributors for medical analysis laboratories, and I have seen that there are those who ask for this ingredient, and I found those who answered that it is available, the number of those who answered the question was a lot,

Will you prepare ink for toning and printing, or what?

I did not print before ,,
But I did get brown translucent strips using thiourea.

 

[AgX]

In the Agfa formulae that come to my mind either Sodiumsulfide or Thiourea are employed.
(In one case Sodiumthioantimonate)

 

[john_s]

This is what you want. The MSDS of Agfa Viradon (new version without expensive selenium) says it's just sodium polysulphide and water. I assume that the corresponding potassium one would also suffice.

https://en.wikipedia.org/wiki/Sodium_polysulfide

There is a substance called Liver of Sulphur used to give metals a certain patina. It might work. It can be acquired from jewellery suppliers.

 

[john_s]

In case anyone is wondering, this was copied from Ryuji Suzuki's web site some years ago:

Polysulfide toning

Polysulfide toners provide direct toning to give darker brownish hue compared to sepia toners. This toning also releases hydrogen sulfide gas, with its characteristic rotten egg odor. This gas is toxic at a higher concentration. Therefore, this toning must be performed in well ventilated area.

Off shelf products include: Kodak Brown Toner (KBT), AGFA Viradon (new version)


T-8 polysulfide brown toner

potassium polysulfide 7.5g

sodium carbonate 2.4g

water to make 1 liter

Relatively brief toning is adequate for image protection, but toning to obrain brown hue may take several minutes with neutral toned paper. This can be accelerated by warming the toning bath. The actual temperature should be tested with test prints to ensure lack of emulsion damage, but should not exceed 40°C.

In order to prevent staining and halt toning immediately, use of a sulfite "stop bath" is highly recommended (almost obligatory for succssful toning). Prepare a tray containing 20g or more of sodium sulfite anhydrous in a liter of water. Toned prints are immediately transferred in to this "stop bath" tray. After a few good agitaion, the print can be sent to rinse and final wash processes. Without this step, the margins and highlight areas may exhibit pink or yellow staining, reducing the paper base's brilliance.

Similarly, a toning bath that is weaker than recommended strength or a bath that is exhausted runs similar risk of staining the print base.

Prints treated with this type of toner are well protected against oxidative attacks.

 

[Philippe-Georges]

Thank you all for the answers!