Determining fixing time with sheet film

Whilst I've done lots of 35mm and 120 B&W developing, I'm still quite a newbie with 4x5 sheet film and I've still got heaps to learn.

When I process 35mm film I can do a fixer test by timing how long a spot of fixer on the film takes to clear properly, and use 2-3 times that period as my fixer time. Is there a way to do an equivalent test with sheet film?

Or is it ok to just use an arbitrary sufficiently long period, such as 2 minutes? (I'm using FP4 or HP5, and I use Ilford Rapid Fixer.)

Thanks.

2 minutes is never a sufficiently long period for fixing! I'd go with 5 to 7 to be on the safe side. You can also do the 35mm leader test: there's essentially no difference between 35mm film and the same type of sheet film, except for size. Every time you shoot a roll of 35mm, save some pieces of leader, or sacrifice a roll so you can test whenever you like.

Correction: I just checked Ilford's fact sheet for its Rapid Fixer. They suggest 2-5 minutes for film. Personally I've found 5 minutes to be a good baseline. It's better to overfix than to underfix. If you underfix, your negatives won't be archival and they may exhibit visible problems, like milkiness or translucency, instead of transparency.

Twice the time for the film to clear, goes from 5 minutes when fresh to 10 minutes when it is almost expired. Add more time for TMAX to loose the purple tint.

Steve

With 35mm film I do the usual "clearing test", where I drop a spot of fixer onto the leader, wait for it to go transparent, and then time how long that spot takes to completely disappear when the rest of the leader is immersed in fixer; that is typically about 25 seconds in my conditions, which means that a safe clearing time is then 1.5 minutes (using the 2-3 multiplier that is usually recommended). I err on the side of caution and use 2 minutes. And if the clearing times start getting noticeably longer I then know that it's time to get rid of the fixer and make a new batch.

Fixing FP4 for 5 minutes sounds like an awfully long time based on the above, and I've not had any problems with the above process on 35mm or on 120.

I note that Sirius Glass mentions TMAX; that's a t-grain film unless I'm mistaken, in which case a 5 minute fixing time is about right (similarly with eg Delta 100), but FP4 is much quicker to fix being a traditional emulsion.

So I'm fairly confident with my 35mm/120 processing, but I'm unsure how much (any? all?) of it translates to 4x5 where I'm still a wet-behind-the-ears newbie

Pretty much everything translates, except obviously the film isn't on a reel. Some folks use trays and some use hanger tanks. I use the "taco method" with rubber bands in a Paterson Super System 4 tank filled with solution up to the funnel so i know there's enough solution to cover. Halfway through fixing (but certainly not during dev or stop), I open the tank and move the bands a little so I don't get underfixed streaks. I can get four sheets to a tank and I haven't had any major problems yet.

Ottrdaemmerung said:

Pretty much everything translates, except obviously the film isn't on a reel. Some folks use trays and some use hanger tanks. I use the "taco method" with rubber bands in a Paterson Super System 4 tank filled with solution up to the funnel so i know there's enough solution to cover. Halfway through fixing (but certainly not during dev or stop), I open the tank and move the bands a little so I don't get underfixed streaks. I can get four sheets to a tank and I haven't had any major problems yet.

Click to expand...

If you use cloth covered hairbands you won't have to move them, the material allows the fixer to come into contact with the film and no marks remain. When I use the taco method I open the tank after four minutes and remove the bands and place the film and fixer in a tray to finish. It allows for visual check of progress as well as letting the film flatten so there is no curl. Kodak recommends minimum of six minutes in fix to remove purple from T-max films. Also, I tried six sheets in an A-P brand tank using taco method, they all turned out fine, scarry experiment.

Thanks for the hairband tip, Rick. I'd heard of using them before instead of rubber bands, but doing it for that reason makes perfect sense now!

cluttered said:

Whilst I've done lots of 35mm and 120 B&W developing, I'm still quite a newbie with 4x5 sheet film and I've still got heaps to learn.

When I process 35mm film I can do a fixer test by timing how long a spot of fixer on the film takes to clear properly, and use 2-3 times that period as my fixer time. Is there a way to do an equivalent test with sheet film?

Or is it ok to just use an arbitrary sufficiently long period, such as 2 minutes? (I'm using FP4 or HP5, and I use Ilford Rapid Fixer.)

Thanks.

Click to expand...

You can do exactly the same fixer clearing time test with a sheet of film, if you want

I don't know what method and equipment you develop your sheet film but here is how I do mine :-

I use a CombiPlan Tank

After the film has been in the Fixer for 60 sec, I pull the top off the tank in daylight and look at the film.

Normally, its clear at this point.

I then leave the film in the Fixer for another 3 minutes (so its been in a total of 4 min) and then proceed to wash the film.

If the film isn't yet fully clear, I keep pulling it out of the Fixer to see if the milkyness has cleared at about 10 sec intervals.

I then leave the film to soak in the Fixer for 4x the time it took to clear the milkyness

Once the Fixer is taking more than 90s to clear the milkyness, I replace the Fixer.

Personally, I find HP5 clears in well under 60s in fresh Ilford Hypam at 1+4 and I never exceed Ilfords recommended capacity of 24sh of 10x8 per litre of diluted fixer.

Fixer is inexpensive in comparison to the cost of film togetherwith all the time and effort you have gone to making the Negs in the first place.

I hope this helps

Martin

hey cluttered

an easy way to fix your film is with 2 baths ..
before you do rolls or sheets do your clip test
but do this instead of what you are doing
put your favorite film clipping in your fixer ( lights on )
note the time it takes your clipping to clear ... and you should fix for 2x that time.
use the time as a baseline ... first bath, for the clear time, short rinse, 2nd bath for the same time ...
periodically do your clip test and still do 2x your clear time ... but when your fix takes 2x the ORIGINAL time
it is time for new fixer ... so make your 2nd bath your first and make a new second bath ... and still keep an eye
on your clip test clearing time ...

you can de-silver or whatever you do with your spent fixer .. and have no worries of over or under fixing your film


have fun !
john

Interesting info, thanks to all the repliers. I'll get the hang of sheet film soon hopefully!

cluttered said:

Interesting info, thanks to all the repliers. I'll get the hang of sheet film soon hopefully!

Click to expand...

Processing sheet film is not more difficult

Its just different

It seems very different when you start - but it isn't really - you will quickly get the hang of it and in six months it will be second nature to you - just like roll film is probably now

Martin