Selenium T-55 question

[karavelov]

Hello to all,

Yesterday I have mixed some selenium toner (see note 1 at the end). I have used Kodak T-55 recipe (see note 2) as base but instead of plain ammonium chloride I used ammonium thiosulfate (mixed from ammonium chloride and sodium thiosulfate). It gives me fairly rapid toning in 2-5 minutes (depends on desired effect). I have leaved the working solution (1+9) in open bottle for the day and it is still quite active.

If you have used T-55 or similar formula, what is expected life of the working solution? Is its activity is lost suddenly? I have never used KRST, so what is the life of its working solution?

Thanks in advance
Luben


Notes:

1. Warning: Do not try to mix yourself at home selenium toner. The selenium powder is quite nasty and should be handled only in chemical lab taking all neccessary preventions (work clothes, gloves, respiration mask, fume hood etc.)

2. Kodak T-55

Water..................... 700ml
Sodium Sulphite .......... 150g
Selenium ................... 6g

Boil until dissolved, wait for cooling and then add

Ammonium chloride ........ 190g
Water to make ........... 1000ml

For use dilute 1:5

 

[john_s]

I haven't made my own yet, but I have collected a few formulas in anticipation of Kodak RST becoming unavailable. I have read that the thiosulphate makes toning much faster and preserves the selenium compound from oxidizing into a useless form. The ammonium ion is there to prevent staining. The MSDS for KRST lists:

Weight % Components (CAS-No.)
55 - 60 Water (7732-18-5)
25 - 30 Ammonium thiosulphate (7783-18-8)
10 - 15 Sodium sulphite (7757-83-7)
1 - 5 Selenious acid, disodium salt (10102-18-8)

KRST working solution can last for months. If the paper has an alkaline bath before toning the toner will last longer: traces of acid fixer will cause the toner to break down.

 

[karavelov]

Thanks John,
That was my intention also, to make KRST alike selenium toner. My concern was also the availability of the toner from Kodak but also the price. I make 8-10 litters of my selenium toner concentrate for the price of 250ml bottle from Kodak which I could not buy here because the local distributor will not take orders for less than 5 bottles - more than 100 Euro (Ughrrr).

Best regards

 

[tim rudman]

Hello to all,

If you have used T-55 or similar formula, what is expected life of the working solution? Is its activity is lost suddenly? I have never used KRST, so what is the life of its working solution?

Thanks in advance
Luben

I started making Se toners before they became available in the UK, back in the early 70's. I stopped making T-55 when KRST became available but I still have stocks of T-56 and it still works today!
Tim