Wash aid and hypo eliminator
SkyGzr
and hypo eliminator. After reading it, I'm quite confused. I'm not sure that
I understood that they were different things.
During a printing session I stack finished prints in a tray of clean water.
When I'm done, I run them all through the second fix. They get one more rinse
in clean water, then Perma Wash, and then straight into the toner. Then they
go into the print washer for an hour or so.
Where would hypo eliminator fit into this process? Is it something I should
care about?
Thanks!
- Kevin
Richard Knoppow
There is more history here than will fit into a post:-) However...
Hypo eliminator is a term used for a solution which converts hypo
into something easily soluble in water. The most effective is Kodak
HE-1 which you mist mix yourself. HE-1 is Hydrogen peroxide hydrolized
with ammonia. It converts the thiosulfate into sulfate, which is
easily washed out. HE-1 was developed by Kodak Labs in the late
1930's. More about this below.
A wash aid is a solution of, basically, 2% Sodium Sulfite. This was
also developed at Kodak Labs partly as a result of investigating sea
water washing.
Its been known for a century that sea water is much more effective
for washing out hypo than fresh water. The sea water must be washed
out afterward since the salts attack the image very vigorously. Sea
water washing became of considerable interest during WW-2 when
photographic materials had to processed on shipboard or elsewhere
there fresh water was at a premium. Kodak wanted to find out how to
duplicate the effectiveness of sea water for washing.
They found that Sodium Sulfite was the most effective salt, in fact,
a properly composed sulfite wash aid is even more effective than sea
water. Plain sulfite works but Kodak found that buffering it to nearly
neutral pH improved its effectiveness by minimising the swelling of
the gelatin, thus minimising the length of the diffusion path the
unwanted chemicals followed in washing. Kodak also added two
sequestering agents to prevent deposits of minerals on the surfaces of
treated film or paper.
Sulfite acts as an ion exchager, in a way similar to the salts in a
water softener. It actually displaces the Thiosulfate ions. It turns
out that it also works on some otherwise insoluble fixer reaction
products.
Hypo Eliminator is effective in removing hypo but does not work on
reaction products. Also, its very alkaline, enough so to damage some
types of emulsions. Since film is easier to wash out than fiber base
paper Hypo Eliminator was recommended for paper only where the
emulsion damage would be inconsequential.
Yet another problem raised its head. In about 1960 T.H.James, of
Kodak Labs discovered that a small residue of hypo left in an emulsion
actually protected the image silver from oxidation! This was such
heresy that the results were not published for a year, in fact not
until after Fuji published similar results.
The amount of hypo must be quite small, larger amounts cause massive
sulfiding of the image causing it to yellow and fade.
Hypo Eliminator was found to be TOO effective, so its use was no
longer recommended except for special instances where absolutely no
hypo was desired.
Wash aid is pretty effective too. The short washing times
recommended by Kodak are so that the protective residue of thiosulfate
will remain in the emulsion.
The two techniques can be used together. Paper treated in Hypo
Eliminator sometimes shows some staining which can be prevented by a
Sulfite or wash aid bath after treating it.
For those interested in experimenting with it Kodak HE-1 is:
Kodak HE-1 Hypo Eliminator
Water 500.0 ml
Hydrogen Peroxide, 3% 125.0 ml
Ammonia, 3% 100.0 ml
Potassium Bromide 1.0 gram
Water to make 1.0 liter
Household Ammonia and drugstore Hydrogen peroxide are about the right
strength. The bromide is very important, it prevents image color
shift.
Treat prints in Kodak Hypo Clearing Agent for three minutes and wash
for ten minutes.
Treat in HE-1 for 6 minutes. Rinse and treat in KHCA again for three
minutes. Wash for twenty minutes.
Other brands of wash aid are all sulfite salts but are not buffered
as is the Kodak product. I think there may be at least one brand which
does not use sulfite but rather a detergent.
Prints treated as above should be toned with sulfide or gold. If not
toned they well be very vulnerable to oxidation by atmospheric
polutants. There is really no advantage to this method other than its
use for some toning treatments where residual hypo may cause bleaching
or staining. For any toner I've ever used a KHCA treatment and
ordinary washing is sufficient.
---
Richard Knoppow
Los Angeles, CA, USA.
dick...@ix.netcom.com
Mike King
rinse and before the wash but most recent studies suggest that getting "all"
the hypo out of a print is a "bad thing"--an archival hypo residual--and I
don't know what that percentage is off the top of my head--is actually
beneficial.
--
darkroommike
......................
"SkyGzr" <sky...@aol.com> wrote in message
news:20020416185106...@mb-fn.aol.com...
John
On Tue, 16 Apr 2002 23:52:39 GMT, dick...@ix.netcom.com (Richard
Knoppow) wrote:
> Hypo Eliminator is effective in removing hypo but does not work on
>reaction products.
Two things on this;
1) Aren't these reaction products that are responsible for
staining in the white areas of a print ?
2) Wouldn't they be removed by the secondary fixing bath ?
Also I've often wondered if using something like KRST 1:9
wouldn't reintroduce enough hypo into the emulsion to take
advantage of the protection that hypo offers the image.
Regards
John S. Douglas, Photographer
http://www.darkroompro.net
Mike
KRST contains a small amount of hypo, so I wonder using the process
with Hypo Clear gets out the hypo and other contaminants from the
fixing stage, then into the KRST, puts back a small amount of hypo
needed for longevity and gives a protective toner to boot.
I think the main concern is all the junk from the fixing bath(s)
getting into the print fibers that should be eliminated.
Mike
On Tue, 16 Apr 2002 23:52:39 GMT, dick...@ix.netcom.com (Richard
Knoppow) wrote:
Rick Schiller
before 5' water wash instead of perma-wash?
Rick Schiller
In article <3cbcb35f....@nntp.ix.netcom.com>, dick...@ix.netcom.com
says...
BJUK
getting a little concerned here, as all I've ever done with prints is plain
water wash after the fixer, and with films, in tank washes with plain water
wash + 1 drop of domestic washing up liquid per litre or so of water. No
problems so far but the oldest negs and prints I have are only four years
old. I am also now just starting to use FB papers (previously RC only) which
I suspect may be more prone to deterioration through inadequate washing/hypo
removal?
As this extra washing stuff is all new to me can anyone suggest a good
resource to read up for someone like me (knowledge stuck with the simple
develop/stop/fix/wash-in-water)?
Thanks in anticipation
Ewen Cameron
Richard Knoppow
Insoluble reaction products eventually decompose causing stains.
Since they are distributed throughout the emulsion the stain is often
an over all stain but can be blotchy, etc. Excessive hypo generally
causes sulfiding of the image. This is akin to toning but is not
controlled. Usually the image turns yellow plus it can become lower in
density.
Two bath fixing will prevent insoluble halides from remaining in the
emulsion. The reaction which makes the unused silver halide soluble is
a complex one which occurs in stages. If there is not enough
thiosulfate left in the fixing bath the process is never completed and
some halide remains. Re-fixing within a short time will remove it but
it changes chemically fairly rapidly. Within two weeks of the original
fixing re-fixing will be ineffective in finishing off the fixing
process.
It turns out that the sulfite wash aid will remove some otherwise
insoluble fixing reaction products. This is insurance against their
being left in the emulsion even when two baths are used.
The capacity of a single bath to finish the fixing process is very
limited. It will continue clearing the emulsion (the cloudiness of the
unfixed emulsion disappears) long after it is incapable of complete
fixing. The capacity of two successive baths is about ten times that
of a single bath. Adding a wash aid treatment after fixing increases
the capacity again by four to ten times. Two bath fixing along with a
wash aid is a very economical way to fix film and paper and insures
long image life.
I have wondered about the residue of thiosulfate left by Kodak Rapid
Selenium Toner. I think there is simply not enough to effect the
protective property of a small residue, at least not at the 1:20
dilution often recommended for after treatment.
In their paper on toner treatments for permanence, Lee, Wood, and
Drago, of Kodak Labs, found that the protective ability of KRST was
not as great when used on film which had been washed completely free
of hypo. This in fact, brings up a question about the problem that IPI
found with the microfilm at the NIH. I have not asked Dr. Nishimura
about this but should. Perhaps the sulfiding which was missing when
KRST was used in this case was not due to a change in KRST but to the
after treatment of the microfilm and absense of residual hypo.
This is a difficult area. Too much hypo will attack the image
causing it to sulfide and turn yellow along with the posibility of
general stain. No hypo leaves the image vulnerable to oxidation,
essentialy the same as tarnish on silverware. Oxidation of the silver
can cause considerable damage to the image. The silver oxide is very
fine and can migrate to the surface of the emulsion where it can be
reduced again to metallic silver by other atmospheric polutant. This
is responsible for the "mirroring" or "bronzing" efffect sometimes
seen on old prints. Since some of the image silver is lost oxidized
images can not ever be fully restored. Those which suffer only from
sulfiding of the silver can be converted back to metallic silver in
many cases.
A small residue of thiosulfate causes just a little sulfiding,
perhaps a single molecule thick, to form on the silver particles, just
enough to give them some protection from oxidizing, since silver
sulfide does not oxidize.
Whan an image is toned with a sulfiding toner much of or all of the
image silver is converted to silver sulfide, but usually of a
different structure than that caused by excessive residual hypo.
Selenium toner also converts the silver, to silver selenide. This is
just as stable as silver sulfide but the toner tends to work on denser
areas first leaving the low density areas without sufficient
protection, unless the toner is used in fairly strong dilution (1:9 or
less) and for a sufficiently long time (three minutes at 1:9).
There are a number of (at least to me) unanswered questions here.
In any case, good practice for film or paper is to use two
successive fixing baths and a wash aid. Don't wash too long. Film and
paper can be treated in KRST or in a sulfiding toner like Kodak Brown
Toner or IPI Silver Lock toner. Treating film is not so imporatant
since the silver particles are much larger than those of paper
emulsion, and less vulnerable to oxidation.
Paper, especially warm tone paper, can be quite vunnerable to
oxidation and should be toned. Display prints especially benifit from
toning since they are exposed to far more air polutants than prints
stored under controlled conditions.
Richard Knoppow
>On Tue, 16 Apr 2002 23:52:39 GMT, dick...@ix.netcom.com (Richard
>Knoppow) wrote:
>
>
>>
>> There is more history here than will fit into a post:-) However...
>> Hypo eliminator is a term used for a solution which converts hypo
>>into something easily soluble in water.
>
>not exactly. Sodium thiosulfate solubility is 2.5 times of sodium
>sulfate (which is an oxidation product of thisulfate). It is
>attraction of thiosulfate ions to gelatine, which is causing problems.
>When oxidised with hydrogen peroxide to sulfates, it loses its binding
>properties.
>
>>The most effective is Kodak
>>HE-1 which you mist mix yourself. HE-1 is Hydrogen peroxide hydrolized
>>with ammonia.
>
>Dick, you are an excellent photographer, but you are not a chemist.
>Sorry, but ammonia does nothing to hydrogen peroxide. Peroxide acts as
>an oxidiser, while ammonia provides alkaline solution and helps to
>remove silver complexes if present.
>
>
>> Sulfite acts as an ion exchager, in a way similar to the salts in a
>>water softener.
>This is not correct. If you want analogy - the gelatine would be an
>ion-exchanger here.
>> It actually displaces the Thiosulfate ions.
>This is correct..
>
>you may wish to reread Chapter 14 from Haist.
I have.
I am not a chemist but slowly learning it:-)
Henn, King, and Crabtree "The Effect of Salt Baths on Hypo and
Silver Elimination" _Photographic Engineering_ 7: 153 (1956)
(Pretty much the same material is in:
Crabtree and Henn, JSMPTE, 65: 379 (1956) and may be easier to find.)
Describe the action of sulfite as being an ion exchange. This is the
paper describing what became Kodak Hypo Clearing Agent.
Hypo Eliminator was described by Crabtree, Eaton, and Muehler in one
of a series of papers on fixing and washing of film. For some reason I
remember their explaining the need for the ammonia as activating the
peroxide.
However, they earlier describe the use of alkaline treatment of film
and paper to remove the mordanting effect of aluminum hardening
agents. Ammonia is recommended because it is effective and evaporates
from the emulsion rapidly making it easy to wash out.
It is the aluminum hardener which, under certain conditions of pH,
makes the emulsion hard to wash. Buffered sulfite wash aid brings the
emulsion to a point where the mordanting action is eliminated but the
hardening is still effective. Whan a carbonate or ammonia bath is used
the hardening is pretty much destroyed.
A sulfite bath is considerably more effective than carbonate.
The effect of pH is specific to aluminum hardener, chrome hardener
does not produce it despite requiring a much lower pH to be effective.
Haist has a very extensive bibliography on fixing and washing in the
chapter you site. I think he includes Richard Meuhler's patent on
hypo eliminator (Kodak HE-1 type).
Richard Knoppow
An awful lot of prints and negatives given convntional processing
have survived many decades. It turns out that the recommendations for
conventional washing of years ago leaves about the right amount of
thiosulfate in the emulsion to protect it. Providing the fixing bath
was reasonably fresh the lifetime of these images is probably better
than those given heroic treatment to remove absolutely all
thiosulfate, once thought to be necessary for archival life.
A sulfite wash aid helps to reduce necesssary wash times. For film
the time is reduced from about 20 minutes to about five minutes.
For paper the time is reduced from about two hours for double weight
paper to about 20 minutes. Longer washes should not be given.
RC paper does not absorb processing solutions and has such a thin
emulsion that it washes out sufficiently in about four minutes without
the use of a wash aid. Film takes longer because its emulsions are
usually much thicker than those of RC paper, or, indeed, fiber paper.
The problem with fiber paper is the support and the baryta layer under
the emulsion. Both tend to hang on to the thiosulfate molecules.
Baryta is a suspension of Barium sulfate in very hard gelatin coated
under the emulsion. Its purpose is to provide a smooth and highly
reflective surface for the emulsion. In RC paper the under layer is of
Polyethylene plastic with Titanium Dioxide dispersed in it, which does
not absorb anything.
Richard Knoppow
>Richard, the 2% sodium sulfite will also work well with film after fixing but
>before 5' water wash instead of perma-wash?
>
>Rick Schiller
>
Yup. The main ingredient in wash aid is sulfite. It doesn't have to
be sodium sulfite, at least one brand uses ammonium sulfite, I think.
Kodak buffers theirs to pH 7 to minimise emulsion swelling. This is
reported to increase wash rate by minimising the diffusion path.
You can make something pretty close to KHCA as follows:
Home Made Sulfite Wash Aid
Stock Solution
Water, at 125F 750.0 ml
Sodium Sulfite, dessicated 100.0 grams
Sodium Bisulfite 25.0 grams
EDTA tetra sodium salt 5.0 grams
Sodium Citrate 5.0 grams
Water to make 1.0 liter
Dilute one part stock to four parts water for use.
The sequestering agents are not absolutely necessary but will
eliminate deposits of minerals on the film or paper surfaces.
rk®
Knoppow) wrote:
> Describe the action of sulfite as being an ion exchange.
Chemists and lay people may differently understand term of "ion
exchanger".
if we use water demineralisator as an example - a resin "rich" in
sodium ions and passing water containg magnesium and calcium
(hardness) ions. Sodium will replace divalent ions, and water becomes
soft. The proces can later be reversed in a regeneration stage. The
same way - a gelatine with thiosulfate ions bonded is treated with
sulfites. Sulfites replace thiosulfate ions, the gelatine later will
freely release sulfites back to washing water. It may be semantics,
but - ion exchangers is either the resin or the gelatine. Then sodium
is equivalent to sulfite ions and calcium is like thiosulfate.
I have no daubt, the general description of wash aid and hypo remover
is corect. And I agree that 5% sodium sulfite is all what you need to
achieve desired permanency.
> For some reason I
>remember their explaining the need for the ammonia as activating the
>peroxide.
as far as I know, and I am always right ;-{) , hydrogen peroxide
changes its oxidising properties depending on pH. For example, if you
want to oxidise thiosulfates, an alkaline environment is better, the
reaction is faster. However, to oxidise sulfites, an acidic solution
is better. To understand why, you need to write a complete reaction,
taking on account water and hydroxyl or H+ ions.
In case of thiosulfates, ammonia provides elevated pH, ammonia forms
soluble complexes with silver ions, helping to remove remaining silver
complexes.
,
> A sulfite bath is considerably more effective than carbonate.
true, but in practice, anything can do.
Richard Knoppow
>On Thu, 18 Apr 2002 23:10:13 GMT, dick...@ix.netcom.com (Richard
>Knoppow) wrote:
>
>
>> Describe the action of sulfite as being an ion exchange.
>Chemists and lay people may differently understand term of "ion
>exchanger".
>if we use water demineralisator as an example - a resin "rich" in
>sodium ions and passing water containg magnesium and calcium
>(hardness) ions. Sodium will replace divalent ions, and water becomes
>soft. The proces can later be reversed in a regeneration stage. The
>same way - a gelatine with thiosulfate ions bonded is treated with
>sulfites. Sulfites replace thiosulfate ions, the gelatine later will
>freely release sulfites back to washing water. It may be semantics,
>but - ion exchangers is either the resin or the gelatine. Then sodium
>is equivalent to sulfite ions and calcium is like thiosulfate.
>I have no daubt, the general description of wash aid and hypo remover
>is corect. And I agree that 5% sodium sulfite is all what you need to
>achieve desired permanency.
OK, I think I have the terminology wrong but understand the process
correctly.
>> For some reason I
>>remember their explaining the need for the ammonia as activating the
>>peroxide.
>
>as far as I know, and I am always right ;-{) , hydrogen peroxide
>changes its oxidising properties depending on pH. For example, if you
>want to oxidise thiosulfates, an alkaline environment is better, the
>reaction is faster. However, to oxidise sulfites, an acidic solution
>is better. To understand why, you need to write a complete reaction,
>taking on account water and hydroxyl or H+ ions.
>In case of thiosulfates, ammonia provides elevated pH, ammonia forms
>soluble complexes with silver ions, helping to remove remaining silver
>complexes.
>,
You are the only person beside myself who is _always_ right. Its
sometimes hard to convince others of this. We need to stick together.
:-)
Again, I am going by my memory of a paper which I have not read for
sometime. My understanding was that the peroxide needed to be
alkalized in order to work but I will re-read the thing.
Henn, King, and Crabtree state that the sulfite wash aid removes
some silver complexes but are not very specific about the reactions.
I was under the impression (I think from the same paper) that the
Peroxide-Ammonium Hydroxide eliminator did do this, removing only
thiosulfate by oxidising it to sulfate. I may be wrong about this, It
sounds like you understad the reactons very well.
>> A sulfite bath is considerably more effective than carbonate.
>
>true, but in practice, anything can do.
>
I am not sure this is true. Sulfite seems to have a specific action
which carbonates and borates do not have. There were extensive
experiments made at Kodak Labs testing all sorts of salts. Carbonate
and metaborate will shift the pH of the emulsion enough to eliminate
the mordanting action of aluminum hardener but seem to have no other
effect. The measured level of thiosulfate in an emulsion was reduced
much more quickly after rthe sulfite bath than after bathing in any
carbonate, sodium metaborate, or sulfate.
As stated before, the mordanting action seems specific to amuminum
hardener. Chrome hardener requires a much more acid solution to work
(around pH 2.9) but the wash rate is about the same as un-hardened
emulsions.
Chrome alum hardener is not used routinely in fixing baths because
it has a limited capacity and tends to leave green stains. The stains
are not a problem for film but are for paper.
There is a very extensive literature on the chemistry of fixing but
much of it is very old and rather obscure. I think Kodak published
most of it. The Journal of the Society of Motion Picture Engineers, or
Motion Picture and Television Engineers as it later became is a rich
source, going back to the 1920's (it was the "Transactions" then).
I became very curious about this some time ago because of seemingly
conflicting explanations of how fixing worked and what was necessary
for archival processing.
My chemistry is limited because I have no formal training in it.
However, I get help occasionally from folks like you and Michael
Gudzinowicz, a Phd chemist, who used to post here occasionally (but I
think now posts mainly to the Pure-Silver mailing list).
As you are certainly aware photography gets you into very deep
waters very quickly as far as chemistry goes. I try to get a good
intuitive understanding but am very aware of the limits of my
knowledge, which I find very frustrating. I like having rigorous and
correct information and abhor the sort of old-wive's-tales so common
in popularizing of fundamentally scientific endevours, like
photography, so welcome help from those with better understanding when
it is shared.
DJ May
on them. Negatives prior to and after do not. During the suspect
time period I was using someone else's darkroom and fixer. The
developer was mine.
Could the blue spots (deposits) be the result of improper fixing or
washing? Initially, I thought it was mold, however I am not sure now
that it seems to only affect the negatives processed in this
particular darkroom. Affected and unaffected negatives were stored in
the same boxes.
Is there any hope for restoring these negatives? Some of them are
quite good otherwise.
Jesse
Richard Knoppow
>I have negatives that I processed in 1976 that are showing blue spots
>on them. Negatives prior to and after do not. During the suspect
>time period I was using someone else's darkroom and fixer. The
>developer was mine.
>
>Could the blue spots (deposits) be the result of improper fixing or
>washing? Initially, I thought it was mold, however I am not sure now
>that it seems to only affect the negatives processed in this
>particular darkroom. Affected and unaffected negatives were stored in
>the same boxes.
>
>Is there any hope for restoring these negatives? Some of them are
>quite good otherwise.
>
>Jesse
>
My previous stuff snipped...
Its hard to know what this is, blue stains are not common. It might
even be the anti-halation dye becoming colored again, something
associated with decomposition of the support, but the film is too new
for that. A soak in a carbonate bath will decolor the dye if that is
what it is. If you don't have cabonate most print developers will do.
If its possible see which side of the film the spots are on. If its
anti-halation dye it will be on the back.
If its on the emulsion side its something else, possibly some silver
oxide on the surface. That can somtimes be removed by treating the
film in a mild reducer. A safe one is fresh film strength rapid fixer
to which 15 grams per liter of Citric Acid is added.
Oxide spots and redox spots, which are usually redish in color, are
from attack by atmospheric polutants. They can occur on well fixed and
well washed film which has not been toned.
Its vaguely possible they might be iron stains but those usually are
immediately apparent after processing.
Nicholas O. Lindan
news:6ee4ff2d.02041...@posting.google.com...
> I have negatives that I processed in 1976 that are showing
blue spots on them.
I would vote iron particles. I have no idea how to get the
stain out, but if it is iron - it should be possible. A
chelating agent, maybe?
Late thought before posting: specs of blue toner? -- shared
darkroom?
--
Cleveland, Ohio noli...@ix.netcom.com
Consulting Engineer: Electronics; Informatics; Photonics.
Nicholas O. Lindan
news:3cbfed34....@nntp.ix.netcom.com...
> rk® <panr...@bigpond.com> wrote:
> You are the only person beside myself who is _always_
right. Its sometimes hard to convince others of this. We
need to stick together. :-)
Oh, dear. "Pride goeth before the fall"
--
--
Nicholas O. Lindan, Cleveland, Ohio noli...@ix.netcom.com