Efficient fixer

[steveo_mcg]

Slightly academic question, what's the most efficient way of diluting fixer? Does stronger fixer do more films? Or is it better to make it as thin as possible?

I accidentally poured my last batch away with one of the final washes and I've only got about 60ml left. I mixed it up and tested it with a bit of leader, it works but takes a while so I'll need to some more sooner than I'd hoped.

 

[Asha]

What are you using Steveo?

I would have thought that a weaker solution would mean that the fixing time will probably have to be extended.....basically same as when a "standard" strength becomes weak with usage.

If it's Ilfords Rapid fixer then mix as 1:4 as per instructions which will give you 300ml solution .....should last quite a while even if you have to extend the fixing duration.

I usually mix 1000ml solution at a time and it lasts for an eternity...occasionally I may add a little more concentrate if it's getting a bit slow to fix the film.

 

[steveo_mcg]

Generic rapid fixer, I needed to make up 500ml to do 120 film so it's pretty weak and as you say I expect it'll need pretty long times. Good idea though I'll bung some more concentrate in when it arrives.

Academic question though is it more efficient to run it as thin as possible and probably replace more often or keep it strong and make it last longer? It's not about cost just curiosity really.

 

[Terrywoodenpic]

If you were to use the fixer neat It would work but not as well as a correctly diluted mix.
a very dilute mix will work in the end.
The rule used to be to fix for twice the time it took to clear.

Rapid fix is (or contains) ammonium thiosulphate. It will fairly quickly go beyond fixing and start attacking the silver image.

Regular fix or "Hypo" is made from Sodium thiosulphate and is slower acting and less active as a silver solvent.

Most fixers contain an acidic element and gelatin hardener, and will neutralise any carried over alkali from development. They usually contain sodium metabisulphide and an alum for this.

 

[Asha]

If you were to use the fixer neat It would work but not as well as a correctly diluted mix.
a very dilute mix will work in the end.
The rule used to be to fix for twice the time it took to clear.

Rapid fix is (or contains) ammonium thiosulphate. It will fairly quickly go beyond fixing and start attacking the silver image.

Regular fix or "Hypo" is made from Sodium thiosulphate and is slower acting and less active as a silver solvent.

Most fixers contain an acidic element and gelatin hardener, and will neutralise any carried over alkali from development. They usually contain sodium metabisulphide and an alum for this.

Some interesting info there....