Salt water to wash film?

[Captain_joe6]

I remember reading somewhere that hypo clearing agent was developed after navy photographers noticed that film washed faster in sea water than in fresh water, brought about by the limited fresh water available on ships. Does anybody happen to know if salt water is a viable alternative to HCA, or is HCA way, way better? Does anybody know the answers when its paper being washed instead of film?

 

[phfitz]

That was the story behind Perma-Wash, but it had to do with sea water in the middle of the ocean. Closer to shore it would be dirtier, doubt it would work well.

just a thought.

 

[Captain_joe6]

I thought the idea was based on the exchange fo ions. And in my mind, salt is very, well, ionic. Would it be possible to mix myself some saltwater to average oceanic salinity and use that?

 

[Sparky]

I don't see why not. I doubt the 'shore water' is ANY different as any other salt water is concerned. But if you want the real deal... order some 'instant ocean' which is a commercially available salt of very high quality including all trace elements (chrome, vanadium, gold, etc..) in their normal concentrations. However - I'm wondering if ordering an equivalent quantity of permawash wouldn't be about the same price. You'd have to check it out.

 

[Tom Hoskinson]

I thought the idea was based on the exchange fo ions. And in my mind, salt is very, well, ionic. Would it be possible to mix myself some saltwater to average oceanic salinity and use that?

A good Hypo Clearing Agent can be made by Mixing 20 grams of Sodium Sulfite in 1 liter of distilled water. As an option, !.5 to 2.0 grams of Sodium Bisulfite can be added as a pH buffer. Soak the film (or paper) in this HCA solution for 1 minute with continuous agitation, then drain and wash.

Sodium Sulfite and Sodium Bisulfite are available inexpensively on the Internet at: The Chemistry Store.

 

[Captain_joe6]

Cool, thanks all! When you're just a poor student working minimum wage and watching in horror as the gas prices continue to skyrocket, a gallon packet of Kodak HCA becomes far more expensive than a container of salt. I manage, though.

 

[Roger Hicks]

A normal wash aid is a 2% sodium sulphite solution in tap water, with up to 0.2% EDTA in hard water areas (0.5% to 1% is all that you need unless the water is VERY hard). That's 20 g/l and 0.5 to 2 g/l.

Strictly, this is a wash aid, not a hypo clearing agent, and there is no need to use either with film or RC paper.

Cheers,

R.

 

[Captain_joe6]

I thought that the unnecessary one was Hypo Eliminator? If Hypo Clearing Agent isn't needed, and it replaces (most of) the thiosulfate ions with sulfite ions, the latter being easier to remove, then what does a 'wash aid' do?

 

[Photo Engineer]

This is a very very old topic. A search of APUG and Photo Net will reveal many identical answers and some new ones.

PE

 

[Michel Hardy-Vallée]

For the difference between (Wash Aid / Hypo Clearing Agent) and Hypo Eliminators:

(there was a url link here which no longer exists)

A wash aid IS a hypo clearing agent; it's just a different word for it. An eliminator is something altogether differently.

 

[Captain_joe6]

I know the difference between hypo eliminator and HCA, but was unsure of any differences between HCA and a 'wash aid.' Now that I know that hypo clearing agent IS a wash aid, the question still stands: is plain saltwater (at 3.5% salinity, the same as the ocean on average) a viable wash aid as compared to the commercially available products (such as Kodak HCA, Heico Perma-Wash, etc.)?

 

[dancqu]

I wonder if wash aid is of any value when
used with film or RC papers. For example, Ilford's
film wash sequence, which is very quick and uses
very little water, includes no hca. Dan

 

[Tom Hoskinson]

I know the difference between hypo eliminator and HCA, but was unsure of any differences between HCA and a 'wash aid.' Now that I know that hypo clearing agent IS a wash aid, the question still stands: is plain saltwater (at 3.5% salinity, the same as the ocean on average) a viable wash aid as compared to the commercially available products (such as Kodak HCA, Heico Perma-Wash, etc.)?

Captain_joe6; Check out this thread: (there was a url link here which no longer exists)

 

[Michel Hardy-Vallée]

I know the difference between hypo eliminator and HCA, but was unsure of any differences between HCA and a 'wash aid.' Now that I know that hypo clearing agent IS a wash aid, the question still stands: is plain saltwater (at 3.5% salinity, the same as the ocean on average) a viable wash aid as compared to the commercially available products (such as Kodak HCA, Heico Perma-Wash, etc.)?

Here are some numbers from Haist, p. 649 of MPP v.1, that come from G.I.P Levenson's paper "The Washing Powers of Water" in Journal of Photographic Science, v.15, n.215. 1967.



Effect of Various Solutions on Thiosulfate Residue in Positive Film

Solution........................pH at M/250...............Effectiveness relative
......................................................................to pure water

Demineralized water...............~6...............................1.0
Sodium chloride.....................6.1...............................1.5
Sodium bisulfite.....................4.1...............................2.8
Sodium sulfate.......................6.4...............................14
Sodium bicarbonate................8.4................................49
Sodium sulfite........................9.2...............................87
Sodium hydroxide...................11.6..............................89


So yes, salted water will clear thiosulfates a tad faster than plain water (1.5x faster). But compared to even using bicarbonate (49x faster), which is as easily available, it would be a bad idea. Actually, Levenson says "the most important component of tap waters favouring rapid washing would appear to be the alkali bicarbonate."

Sodium sulfite is the best overall hypo clearing agent (87x faster), and for an efficiency similar to sodium hydroxide, it is way less hazardous to manipulate.

Gee whiz, did I just shatter another long-standing myth of folk photochemistery?

 

[Photo Engineer]

Michel;

I doubt it. Your information is accurate. It should contain information on effects of these things on image stability though as it varies due to the final pH possible from these treatments and the effect of washing out too much hypo. We have all heard of the fact that there must be a tiny amount of sulfur from hypo or sulfite or thiocyanate (Sistan for example) to get the best in image stability.

PE

 

[Michel Hardy-Vallée]

I wonder if wash aid is of any value when
used with film or RC papers. For example, Ilford's
film wash sequence, which is very quick and uses
very little water, includes no hca. Dan

From Haist again, p. 639
"Film emulsion begins to retain thiosulfates when a potassium allum fixing bath (pH below 4.9) is about half exhausted; paper pritns begin to retain silver thiosulfates with the first print processed"

"Print" Meaning of course FB prints in the present context.

Therefore, you shouldn't worry about HCA with RC and film as long as you stick to fresh fixer; the fiber base of the FB paper is the real battleground of thiosulfates. And as I wrote above, normal tap water contains bicarbonate ions, which help to wash off thiosulfates.

 

[Michel Hardy-Vallée]

Michel;

I doubt it. Your information is accurate. It should contain information on effects of these things on image stability though as it varies due to the final pH possible from these treatments and the effect of washing out too much hypo. We have all heard of the fact that there must be a tiny amount of sulfur from hypo or sulfite or thiocyanate (Sistan for example) to get the best in image stability.

PE

Right, I think one of the debates on image stability is whether some residual thiosulfates are harmful or not to long-term stability. IIRC, it was found out eventually that a little bit of them help, hence discrediting the use of hypo eliminator solutions.

So we should probably bracket my information with "In so far as common procedures of hypo clearing are concerned, sodium bicarbonate would be a better practical choice than sodium chloride to replicate the effect of sodium sulfite."

 

[Photo Engineer]

You have summed it up nicely.

BTW, there is a study of baryta FB paper and the FB paper itself with regard to hypo retention, and it turns out that the baryta increases hypo retention manyfold. I wish I had bookmarked that study. IDK where it was or when I read it, but it is true. RC papers retain hypo a lot less, but since they are not FB in the true sense, there is no comparison.

This was one of the reasons I expressed concern over the use of TEA in final rinse baths and hypo baths several weeks ago. Baryta tends to want to adsorb some components of photographic solutions and therefore results comparing FB and RC and Film for image stability and post process retention of chemicals can give different results.

For the same reason, raw stock keeping of products on these three supports differ unless the formula is not changed for the support.

PE

 

[gainer]

Sea water, of course, has many other things besdie sodium chloride. It contains every kind of molecule that is in living things. Sea water, I believe, is not all the same. I know for fact that natural salt water is not the same everywhere. I have heard it said that getting the last bit of hypo out of a print is not necessarily the best thing to do.

 

[gainer]

While I was writing the above a bunch of other postings were made. I wouldn't hesitate if I lived by a sea coast to use sea water for the preliminary wash. My mountain spring and well water is hard, not salty, good for indigestion and any other uses of calcium and magnesium, not much good for developers with carbonate.

 

[Paul Howell]

When I worked in Southern Italy I lived a block form the ocean, for several years I washed my FB prints in sea water followed by tap water (not much different from salt water where I lived) then soaked in distilled water and air dried. I had a net bag that I would toss into a small cove for 3 or 4 hours. That was over 20 years ago, I cannot tell any difference from the prints that washed in portable tap water.

 

[dancqu]

From Haist again, p. 639 "Film emulsion begins
to retain thiosulfates when a potassium allum fixing
bath (pH below 4.9) is about half exhausted; paper
pritns begin to retain silver thiosulfates with the
first print processed"

I really do not lend much weight to Haist's findings.
After all "...potassium alum fixing bath (ph below 4.9)..."
and "The Washing Powers of Water" 1967, etc.

Today, even where acidic fixers are used, they do
for the most part contain no hardeners. None of his
work from that era concerned the thin pre-hardened
emulsions of today.

As for shorter washes how about six seconds? Ilford's
film sequence takes about five minutes. Divide that by
eighty seven? Less then six seconds.

I'm sure much of Haist's work is still pertinent from
one point of view or another. Some though is just
plain dated. Dan

 

[Photo Engineer]

Dan;

Most of the emulsions Grant worked with were THICKER than those of today due to coating technology.

PE

 

[Michel Hardy-Vallée]

Dan,

I will leave it to you to sort through the scientific literature and come up with more recent numbers. From here, that is as best as I can find.

 

[Captain_joe6]

From Haist again, p. 639
"...paper pritns begin to retain silver thiosulfates with the first print processed"

"Print" Meaning of course FB prints in the present context.

Therefore, ... the fiber base of the FB paper is the real battleground of thiosulfates.

Now, I'm no chemist (passed high school chemistry by the skin of my teeth), but my understanding of these passages is that FB prints will, without a dedicated 'hypo eliminator,' retain some thiosulfate no matter what. Is that right?

Next to that, would it be correct to assume that a bath of sodium sulfite or even plain old sodium bicarbonate would serve as extremely potent wash aids? Does anybody happen to know the effectiveness of the current commercial products relative to tap water?