TF 5 Fixer & KRST
I'm now using the Formulary's TF 5 fixer for my prints (fiber paper). It says to wash them 15-25 minutes after a one minute fix. I tone my prints for a bit in KRST. Do I now follow the directions on the Kodak bottle for washing prints or continue the original schedule for washing?
The Kodak product says to fix twice, which I no longer do since I started using TF 5. Should I be using a wash aid? If so is this something I can mix up in house? I don't mind buying chemicals etc. but the cost of shipping is a real bite in the wallet.
I have wondered this as well because I have yet to see a definitive recommendation. I believe I have had staining in the past going right from TF to selenium, so I do a fairly thorough wash for 5-10 minutes, then selenium, and finally an archival wash (I happen to use Ilford wash aid and their timing recommendation) That works for me, but I'd be interested in a more scientific examination if anyone has one.
Chris, there's thiosulfate in KRST, so a washing aid will help to remove it, after toning. I don't have any experience of TF 5, however, so I cannot judge its ability to convert the complex less-soluble byproducts of fixing (argentothiosulfates) to those that wash out more easily. In general, for what I know, those are not an issue if your fixer is quite fresh, and they become an issue when it is exhausting, while the 2nd fixer, being still fresh, is able to work on them. Two things make it more complex, however: KRST has thiosulfate, and so I expect it might help to convert the insoluble argentothiosulfates into the more soluble ones, and a good washing aid helps remove them faster than just water, as long as it is fresh and potent, that is the sodium sulfite has not oxidised yet.
My suggestion would be to include a washing aid in your process, and to test for residual thiosulphate after the washing to establish the correct duration for your conditions, temperature, washer type, and water hardness.
A simple washing aid, following Anchell:
Water (125F/52C) 750 ml
Sodium sulfite 200g
Sodium bisulfite 50g (Achell writes this is of more importance for film and can be skipped for paper to improve gloss)
Water to make 1 liter
This makes stock, dilute 1+9 to make working solution. If you don't work often and prefer not to keep stock solutions for long, you can just mix the working strength wash using 20g sodium sulfite in 1l water.
Chris, I have been using TF4 since it came out with no stain problems. TF5 is similar without the stabilizer/buffer which helps maintain PH if using an acidic stop. Yes, use a wash aid for 10 min after toning prints. My final wash is 30 to 40 when processing fiber prints after the toning and wash aid step.
Follow Ilford's recommendations to rinse prints for 5 min before and after toning. Only then move prints to the final wash step.
Warning: for optimum permanence limit fix capacity to (10) 8x10 prints in 1L of fix if using a one tray fix line. The reason is silver buildup in the fix.
Testing is the only sure way to know.
Thanks for the help. I ordered a test kit.
Richard, I have been in the ballpark with the number of prints going through a liter of fixer as you recommend.
Also I'll be making up my own wash aid. After I ran out of Perma Wash I haven't used any aid so I'll test those prints.