Plain hypo. How much needed per roll of film?

[John51]

I've got a tub of Sodium Thiosuphate and I came across the plain hypo formula of 240g per litre. I'm fine with it not keeping overnight, a one shot fixer suits my on/off film usage. An acid stop bath is recommended but I've got citric acid so no problem there.

240g per litre means 300ml of hypo would be 72g. I'd like to use less if possible. What's the minimum amount of Sodium Thiosuphate that can be used for one roll of film without worrying about it doing its job properly?

 

[Gerald C Koch]

Such a bath is fine for repeated use Measure how long it takes for a fresh bath to clear film. When the clearing time has become doubled it's time for a fresh bath. You can extend its use by using a two bath system. Use the bath FS. If you use it diluted you run the risk of incomplete fixation.

 

[darkroommike]

If you chose to use plain hypo for a roll of film you could try a more dilute fix, most plain fix formulas assume that you are fixing paper and each 8x10 sheet of paper has the same area as a roll of film (give or take). And then just fix for twice the time it takes to clear your roll of film.

 

[Gerald C Koch]

A bit of clarification. Film fixers contain about half as mush thiosulfate as for paper fixers. Use the above formula at half strength for films. Again you can reuse a bath multiple times.

 

[MattKing]

A bit of clarification. Film fixers contain about half as mush thiosulfate as for paper fixers. Use the above formula at half strength for films. Again you can reuse a bath multiple times.

Gerald:
I think you may have this switched around.
In my experience, film fixers tend to be twice as concentrated as paper fixers (1 + 4 vs 1 + 9), not the other way around.

 

[Gerald C Koch]

Gerald:
I think you may have this switched around.
In my experience, film fixers tend to be twice as concentrated as paper fixers (1 + 4 vs 1 + 9), not the other way around.

My bad. All I can say is that nothing is going right today.