fixer question

[chris_dilenardo]

after a disaster last week kindly helped out(saved!) by a fellow

photonet user, i dropped a film leader into fixer to see when it

went clear( to see if its exhausted) and left it there in the jug

whilst the film developed. now after following the instructions on

developing(neopan 400 @9 min in the developer ive got)i noticed a

purplish haze to previous negatives ( both ilford delta and a kodak

one i cant remember)the bit of film that was left in the fixer jug

after about 11 min went totally clear, with no colour tinge to it. i

usually fix the film for about 3 min. should i fix for like 10 min

to get rid of all colour tinge to the negative? or will something

bad happen after a certain time? im learning all the time thanks to

you kind fellas so any info to me is useful info.

thanks once again

chris

[silent1]

Ammonium Thiosulphate rapid fixers will bleach film when in an acid solution. That means that overfixing will (slowly) destroy the image by dissolving away the image silver, with damage most noticeable in the shadows, where there is less to lose and the invididual grains are smaller.

 

However, this typically takes a long time at normal film strength for fixer; fixing for ten minutes instead of three likely won't produce a difference you can see with a loupe or in a print (though it might produce a measurable difference if you use a densitometer). I've intentionally bleached film with hyperacid rapid fixer, made by adding enough stop bath concentrate for twice the volume to film strength working solution fixer; it took about an hour in that solution to produce bleaching that was obvious to the eye. One could probably bleach faster still by making a bleaching fixer from ammonium thiosulphate and sulfuric acid, if one wanted to -- but if one wants to bleach (instead of trying to improvise as I was doing) it's much easier and faster, yet still controllable to use dichromate or permanganate bleachers in sulfuric acid solution, or thiocyanate in hydrochloric acid solution, depending on whether you want to remove silver or rehalogenate it.

 

For fixing, under a half hour in fresh film strength fixer most likely won't do any damage you can detect easily -- though I wouldn't try that with Tech Pan or microfilms, which have uniform, very tiny grain and thus will bleach faster and give now warning when the image is about to vanish entirely. Those films tend to fix very quickly anyway, though, and have no color residue in my experience.

[kaiyen]

I have occaisionally used the clip test as well with my fixer, though now I just use a rule of thumb as to when to get rid of it (I use a 2-bath fix method, too). I thought you were supposed to agitate the fixer while you did it - if you just leave it there, the fixer will exhaust locally and only through very slow diffusion and convection will it clear the film.

 

allan

[zensphoto]

Try fixing for 5 or 6 minutes, I know the Kodak Fixer pouch says 5 - 10 minutes, I usually fix for 5 or 6 minutes, rinse, use Hypo for 2 minutes then wash for 6 minutes. Photo flo for 30 seconds and poof perfect negatives. I have since November 2003 developed over 400 rolls of B&W of various brands. Remember to Agitate the fixer every 30 seconds one turn will do it. I am doing two rolls of 36 at a time using HC-110 and sometimes D76.

 

Have a great day !

[jim_a]

I fought this for a while and read all the "cures." The only real solution IMO is to go to a two-bath fixing method. Recently I ran a roll of T-Max 100 and Neopan 400 in fixer that should have still been good based on the amount of film run through it. I kept two snippets from each film. I fixed them for three times the "normal" amount and then took one snippet from each emulsion and and put them into fresh fixer. In just a minute each film was noticeably clearer than the one that only had the first fixer. Two-bath fixer. Give it a try. I'm now a believer. Also see this link: <a href="http://tinyurl.com/29ach">http://tinyurl.com/29ach</a>, specifically the first and third posts.<P>

 

I like Neopan 400. It also doesn't seem to have a tint to the base like the New Tri-X or T-Max or Delta films.

[john_cook1]

Chris, here is Ilfords pdf technical instructions for using their Rapid Fixer (an excellent product).

 

http://www.ilford.com/html/us_english/pdf/Rapid_fixer.pdf

 

Follow these instructions exactly and everything will be just fine. If the film has a slight tint, believe me - its supposed to be there. When it comes to using chemicals, the manufacturer knows best.

[richard_cochran]

Fixer isn't the only thing that removes dyes. Certain developers

have a strong tendency to strip dyes from film, as anyone who

has developed Tri-X in Rodinal can attest (when you pour out

the developer, it's very purple.) T-max has a pinkish dye

that is removed by sufficient washing in ordinary water; after

fixing, three changes of water in 15 minutes will turn the film

from pink to clear.

<p>

In other words, just because a film has a color tint when you

do the fixer clearing test doesn't mean it will have the color

tint when you process it normally.

<p>

The purpose of fixer is to remove the silver halide from the

film, changing it from milky to clear. Fixing for twice the

clearing time is normally recommended. Overfixing will

bleach the image, and can lead to long-term stability problems,

so overfixing should be avoided.

<p>

A slight color tint from a sensitizing dye may not be such

an awful thing; you can probably just live with it. But

if you really must get rid of it, just wash the film properly.

[frank.schifano]

Amen to that. Richard has it right on the money. Not all films are on a perfectly clear base, so don't confuse the base color with ant dye that might be left in the emulsion. HCA (hypo clearing agent) will help take out any of the dyes that are left after fixing, but so will a proper wash.

[rowland_mowrey]

AFAIK, all EK films are on clear bases.

 

A colored base defeats the purpose of a transparent film.

 

However, during manufacture, films have antihalation dyes added to enhance sharpness and control speed. The also have sensitizing dyes added to achieve panchromatic sensitization.

 

If your process is not right on the money, these dyes can be retained in the film. If they are retained, the film can be pink, grey, or blue. This is not the support, but rather the dyes put in during manufacture and which should wash out in a good process.

 

In addition, all films have a very slight fog level. This will cause a dmin that appears greyish blue. The higher the fog, the greater the overall cast. This is due to improper keeping and processing.

 

In either event, a dmin under about 0.20 should not be a problem, but over this value would indicate a process or keeping problem.

 

Just a FYI post.

 

Ron Mowrey

[gareth_harper]

I use Ilford Rapid fix. I fix for 3 minutes with traditional films like APX and Tri-X. With modern films like Tmax I fix for 6 minutes. Both times are for fresh rapid fix at film strength. I've had no problems. Yes the film base has a very very slight tint.

[photojim]

Extending the wash is a much better way of getting rid of the dye than is overfixing, which causes harmful effects. Incidentally, the dye is harmless and does not affect printing, except to result in slightly longer printing times. It isn't important to eliminate it.

[lex_jenkins]

Ron, while film bases are presumably clear (and that term may be open to some interpretation), I've noticed from Kodak's literature that at least some emulsions use different bases on different formats.

 

Naturally, whenever I recall something I think I've seen on Kodak's website I can never find that particular page again.

 

Does anyone else recall seeing a page of such information; and would different bases used on Tri-X in 35mm and Tri-X in medium format produce differences in perceived "clarity"? (I'm not implying that Tri-X does use different bases, BTW.)