Rapid Fixer -- 1+3 vs 1+4

bvy

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Another fixer thread from me -- sorry.

Some time back I dedicated a 600ml bottle to fixer. I marked a fill line for stock fixer, topped off with water, and stirred.

The other day I noticed that this fill line is based on 1+3 and not 1+4 (150ml instead of 120ml). So I've been fixing my film at 1+3 for who knows how long.

So what's the risk? Some time back I had a mysterious problem with emulsion flaking in Acros and wonder if this could have been the culprit.

Thanks.
 

pentaxuser

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I am not a chemist so can't give an expert opinion but based on the difference of 30ml of stock fixer I'd be surprised if this is the cause of any problems. I know this may be a flawed comparison as this example is paper but I have seen some users stating that they fix paper at 1+4 instead of the usual 1+9 so proportionally a much greater increase in concentration and I have never seen reports of problems.

pentaxuser
 

MattKing

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IIRC, several years ago Simon Galley addressed the change in dilution instructions for Ilford Rapid fix.
For a long time, the instructions said 1 + 3. They then changed the instructions to say 1 + 4, and even went to the effort of pasting new labels over their existing stock of bottles to reflect that change.
The reason for the change? They determined the 1 + 4 dilution worked just as well, and the additional economy made it easier to sell the fixer.
 

Doremus Scudder

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Ilford Rapid Fixer and Hypam indicate a 1+4 dilution for film. Kodak Rapid Fix dilutes 1:3 (1+3). Other brands are one or the other usually. Do read the mixing instructions

As for using fixer too strong: a 1+3 dilution for the Ilford products probably will make little difference (you did do the clearing test, right ). However using rapid fixers too strong actually decreases their ability to fix; there has to be enough water in the mix to make things work correctly.

Best,

Doremus
 
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bvy

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Well they're not going to sell more fixer that way (!). But good for them and good for us. And good for the environment too...

I wonder how long ago they changed from 1+3, and if it could be that I based my measuring on those old instructions.
 

MattKing

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bvy said:
Well they're not going to sell more fixer that way (!). But good for them and good for us. And good for the environment too...

I wonder how long ago they changed from 1+3, and if it could be that I based my measuring on those old instructions.
Click to expand...
If you follow the instructions and re-use your film fixer and monitor its response using a clip test, a batch of 1 + 4 fixer will give you less yield than a batch of 1 + 3 fixer. Essentially, the bottle of concentrate should fix approximately the same amount of film, whether you use 1 + 3 or 1 + 4.
As for the time of the change, I would guess something like 2005, because I recall from around then having a couple of bottles with both the new label (on top) and the old label (underneath).
 
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