Fixing Fomatone paper.

Hello all
I have a question regarding fixing Foma papers specifically Fomatone MG with Ilford rapid fixer.
The Foma data sheet states 3 minutes at 1:5 dilution with Foma's own fixer 'Fomafix' but what does this mean for fixing with another brand? In this case Ilford rapid fixer.
If I follow the stated 1 minute at 1:4 for Ilford's fixer with Fomatone paper will I be effectively underfixing?
Or, if I follow Foma's instruction of 3 minutes will it be increasingly difficult to remove the fixer?
Does anyone have experience with this combination?
Thank you for any advice/opinions in advance.

Can't give a direct answer for paper. But I use clearing tests (with film clips) to check my fixer (whether for film or paper). Clearing times with non-tabular film:

• Ilford rapid fixer 1+4 : 30"
• Fomafix 1+5 40"

The difference is small and arguably accounted for by the difference in dilution. So I guess that the Ilford and Foma fixer concentrates are equivalent (if not identical). Possibly most of the difference (1' versus 3') comes from different evaluations of safety factors. Fix for 3 minutes if that makes you feel safer. That should not slow down your workflow: you can turn the light on to evaluate a test strip as soon as it is in the fixer provided you used an acid stop bath. Once evaluated, put it back in fixer until the next strip or print comes along; that should give ample time for proper fixing. Overfixing is not an issue up to much longer times.

Keep in mind that there is a difference in recommended fixing time for FB versus RC papers.

I've been fixing Fomatone in Ilford Rapid Fix, using Ilford's instructions, and haven't noticed any detrimental effects. Though I haven't run any spesific tests to see if the paper might be under-fixed.

Possible test: use un-developed piece of paper (max halide content); short wash; a drop of Selenium toner or thiourea (a.k.a. thiocarbamide) solution will stain the paper if incompletely fixed. Disclaimer: this should work but I have not tested it personally.

Actual fixing time should have a margin of safety wrt to minimum fixing time. Partly used fixer will require longer time than fresh fixer.

If the paper is washed properly, the retained silver test will show if it's completely fixed. Or try developing an exposed, undeveloped bit of paper after fixing. If there are silver halides left in the paper, density should increase in the developer.

See also: https://www.photrio.com/forum/threads/fixer-testing-for-paper.119918/

Yes. Test for residual silver. I prefer to use Kodak Rapid Selenium Toner 1+9 instead of the ST-1 test for this since I always have it on hand and it has an indefinite shelf-life, unlike the ST-1 test. It's an easy test. Just place a drop of the reagent on a clear border or other unexposed area of the print, wait three minutes, blot and look. Any stain other than a faint yellow is indicative of underfixing. Adjust your fixing regime accordingly.

Best,

Doremus

Not to be pedantic. But IMO what is needed is a test for residual silver halides. Maybe the several mentions of "test for residual silver" are just some shorthand sanctioned by usage? The presence of silver in a finished print is normal; even desirable.

Ilford Rapid Fixer notice does not mention any specific paper brand, so I assume that fixing time is the same regardless the brand. This is only parameter to consider is RC or fiber paper.

I used Ilford RF with a lot of different papers (Ilford, Agfa, Oriental, Kodak, etc) without any additional question. I guess Ilford knows their job better than anyone here.