Paper Fixing Times

[jeroldharter]

For various reasons, I have settled on a double fixing bath for fiber base paper rather than a single fixing bath. I use Hypam at the 1:9 paper dilution. The clearing time for my paper is 45 seconds.

From what I read, the fixing time should be twice the clearing time (or perhaps 3 times the clearing time for Polymax).

My question is whether "twice the clearing time" is the total fixing time (so that each of the two fixing baths should be 45 seconds for a total of 90 seconds); or is the fixing time 90 seconds in each of the two baths (for a total of 180 seconds).

Thanks.

 

[Lowell Huff]

45 seconds to 60 seconds total in fresh fixer is plenty.

 

[jgjbowen]

90 seconds in each

 

[timeUnit]

According to Ilford, too much fixing time will decrease image stability, and make washing difficult.

I follow their recommendation and use a 1+4 strength Hypam fixer bath for 60 sec. No more, no less. After that I use their washing sequence to get "archival" prints. I'll see in a few 100 years if the prints are OK. ;-)

 

[Doremus Scudder]

I also use Hypam 1:9, two-bath. I fix for 90 seconds in each bath with good results. I haven't tested for a while, but last time I did residual silver and thiosulfate compounds were all very, very good after a 10 minute hypo-clearing bath and a 60 minute wash. Be sure not to exceed fixer capacity (It seems you have that part down).

For me, the 1:9 dilution two-bath method works best since I wash and dry after the first bath and then use the second bath as step one of a toning session.

I have read and re-read the Ilford suggestions many times, and they seem to suggest that at the 1:4 strength, one-bath, the capacity of the fixer is rather limited if one wishes to process for optimum permanence. Two-bath at 1:4 is wasteful, therefore my decision to use the 1:9 dilution.

Yes, too much fixing time will bleach the image a bit and make washing difficult. That is another reason for the 1:9 dilution. It is just easier to use the longer time for me.

Hope this helps,

Doremus Scudder

 

[timeUnit]

The point of the Ilford method is of course to save water. They like to do that in the UK, I've heard!

 

[mcfactor]

How much fixing is too much fixing? I leave my prints for about 90 seconds in 1:4 Ilford rapid, but I see plenty of people doing far longer. At approximately what time will my image begin to degrade?

 

[Doremus Scudder]

How much fixing is too much? From what I understand, there are two considerations. First, and probably most important to most is that extended fixing of fiber-base papers can allow the fixing compounds to soak further into the paper base, making them more difficult to wash out. Washing is never perfect, and the longer the fix, the more residual thiosulfates, etc. remain in the print.

Secondly,overfixing can bleach the image somewhat. This results from fixer attacking the image silver and converting it to soluable compounds. This would have to be really excessive to make much of a difference, although it is bandied around quite a lot. I once left a print in the fix for an hour just to see if I could bleach it a bit... No visible effects.

There is an optimum time for fixing when the fixing process is complete and the washing time is minimum. However this is only easily controllable if fresh fix is used for each print. In reality, the fixing speed and efficiency is compromised each time a print is fixed in the solution. (This is why "twice" the clearing time is recommended, it's a "fudge factor"). Manufacturer's recommended times always include a generous fudge factor. One of the reasons two-bath fixing is so much more efficient is that the bulk of the fixer by-products are formed in, and remain in, the first fixing bath, leaving the second bath relatively fresh. In the fresher bath, fewer complex (read "harder to wash out") compounds remain in the solution and in the paper.

That said, underfixing is a much greater danger than over-fixing. I try to err on the side of too much fixing and then try to compensate somewhat for that with a longer hypo-clearing step and wash time. Two hours or longer of wash is fine with me! Get rid of those artificial-looking optical brighteners!

Fixer capacity varies depending on the acceptable levels of residual silver in the print. "Commercial" standards, which is the usual fixer recommendation, leave significantly more silver in the print than "processing for optimum permanence." Read the Ilford tech sheet on fixing black-and-white films and you can arrive at your own conclusions about capacity. For me, I use the two-bath method at the one-bath capacity, never substitute the second bath for the first, and increase fixing times toward the end of the capacity (from 90 seconds to a minute). I'm probably over-fixing, but the last thing I want is a print to come back from a gallery or a customer with degradation due to improper fixing!

Best,

Doremus Scudder

 

[Ole]

...

Secondly,overfixing can bleach the image somewhat. This results from fixer attacking the image silver and converting it to soluable compounds. This would have to be really excessive to make much of a difference, although it is bandied around quite a lot. I once left a print in the fix for an hour just to see if I could bleach it a bit... No visible effects.
...

The effect is quite obvious with some materials. I use a very thin solution of rapid fix to clear the highlights of POP prints and van dyke prints if the're too "muddy". With the very small silver grains in these emulsions it works very fast.

Similarly I have observed loss of highlight detail in lith prints by overfixing.

For all of these processes a plain sodium thiosulfate fixer is recommended; an acidic rapid fix will inevitably bleach the image.