Proper dilution of Kodak Rapid Fixer Solution A ???

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Phil Glaser - 28 Apr 2004 21:53 GMT

Hi,

I need to dilute Kodak Rapid Fixer solution A only (for fixing prints
that are to be toned) and am unsure as to the proper dilution. I see
one place on Kodak's web site that says 1:3 (which sounds correct for
film but not paper), another that says 1:7). Then again, I've
extrapolated from the instructions that come with the fixer (which
include instructions only for dilution with solution B) and my results
don't match either 1:3 or 1:7 (but I'm mathematically challenged).

What is the magic ratio?

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Jazztptman - 29 Apr 2004 01:01 GMT

Phil, If you are using a longer fixing time (2-4 minutes for RC and 5-10' for
fiber base papers) in a tray and do not need a hardening fixer, you can use the
paper dilution of 1 portion of Part A to 7 portions of water. If a
non-hardening fix is prerred, use Part A only - Part B is the hardener.

The more concentrated 1:3 ratio is used in rapid roller transport B&W paper
processors with fix and wash times in the range of 20 seconds each. Only part A
is used in this application as the hardener would shrink the emulsion and not
allow proper fixing or wash to take place in such a short time.
Bernie

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Phil Glaser - 29 Apr 2004 14:17 GMT

> Phil, If you are using a longer fixing time (2-4 minutes for RC and 5-10' for
> fiber base papers) in a tray and do not need a hardening fixer, you can use the
> paper dilution of 1 portion of Part A to 7 portions of water. If a
> non-hardening fix is prerred, use Part A only - Part B is the hardener.

I need to clarify some things Both the fixer and paper instructions
suggest that the fixing time with rapid fixer is 1 minute for RC,
whereas the instructions for Kodafix suggest 2 minutes for RC. So when
you say to fix RC for 2-4 minutes, is it because the directions are
not conservative enough, or because leaving out the hardener
necessitates a longer fixing time? I would have hoped that, with
_rapid_ fixer, I would not have to fix for as long as with Kodafix.

The other thing is that I what I am starting with is not the powder,
but the liquid concentrate of Part A. Do I still use 1:7 part A to
water with the liquid concentrate? Ther reason I ask is that the
instructions suggest the relative amounts to make one gallon (which is
way more working solutiion than I need at any given time) and it does
not look to me like the dilution, based on extrapolation, would work
out to 1:7.

Thanks!

--Phil

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Jazztptman - 30 Apr 2004 04:49 GMT

>>Phil said: I need to clarify some things Both the fixer and paper

instructions suggest that the fixing time with rapid fixer is 1 minute for RC,
whereas the instructions for Kodafix suggest 2 minutes for RC. So when you say
to fix RC for 2-4 minutes, is it because the directions are not conservative
enough, or because leaving out the hardener necessitates a longer fixing time?
<<
Phil I was going by memory. I think you're correct and Kodak calls for 1-2
minutes with RC papers.

>>I would have hoped that, with rapid fixer, I would not have to fix for as

long as with Kodafix.<<

Kodafix (the liquid concentrate) is also a "rapid" ammonium hypo fixer. Not
much different from Rapid Fixer. The only "slow" fixer Kodak has is the powdred
Kodak Fixer, which is a sodium hypo fix.

>>The other thing is that I what I am starting with is not the powder, but the

liquid concentrate of Part A. Do I still use 1:7 part A to water with the
liquid concentrate? Ther reason I ask is that the
instructions suggest the relative amounts to make one gallon (which is way more
working solutiion than I need at any given time) and it does not look to me
like the dilution, based on extrapolation, would work out to 1:7.<<

Yes, 1:7 for the liquid concentrate Rapid Fixer. 1 part of part A concentrate
to 7 parts water.The directions probably also call for some part B which is why
the volumes do not work out to an exact 1:7 dilution. Good luck and have fun
printing.

Bernie

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Richard Knoppow - 03 May 2004 06:04 GMT

> Hi,
>
[quoted text clipped - 7 lines]
>
> What is the magic ratio?

Rapid fixers can cause bleaching of fine grain silver
images typical of paper prints if the paper is left in them
longer than necessary for fixing. For that reason most
manufacturers of "rapid" fixers give two dilutions: one for
film and another for paper. For film, which is more
difficult to fix than paper, the usual dilution is 1:3 or
1:4, for paper the dilution is 1:7. The fixing time is about
doubled when paper dilution is used. If you are a careful
worker in the darkroom you can use film strength rapid fixer
for paper, but beware that the fixing time will be between
30 seconds and 2 minutes, depending on the paper. When rapid
fixer is used in a neutral form it does not bleach so the
whole issue becomes moot. If no hardener is used the fixer
can be neutral. Agfa color fixer is neutral pH rapid fixer.
Also, Kodak Rapid Fixer with Hardener, can be used without
the hardener added. The pH is less acid this way (but I
don't know what it is) so there is less chance of bleaching.
With alum hardener the pH of a fixing bath is around 4.5.
Hardener is not needed by many of today's films and
papers which have much harder emulsions than those of some
years ago. The hardener prevents excessive swelling of the
gelatin in the fixing bath and wash. For emulsions that are
soft and swell excessively the presence of a hardener can
actually decrease fixing time by shortening the diffusion
path fresh fixer must take to get into the emulsion and
fixer reaction products must take to leave it.

Signature

---
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com

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