Salt water to wash film?

[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?

[Michel Hardy-Vallée]

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?

1) From what I've read, and what PE has said, yes, there will be residual thiosulfates when only a wash aid/hypo clear is used, but archival processing science suggests that this might not be such a bad thing. Hypo eliminators are not much favoured these days.

2) Yes, a bath of sodium sulfite or bicarbonate is a better way to clear thiosulfates than plain tap water. Of course, that is only important when you use FB paper. With film or RC, the emulsion washes off pretty quickly, and the base does not retain thio. It is always important to use fresh fixer if you want to avoid too much thio buildup in all products (ergo longer washing times).

3) If you get the MSDS for commercial products, you will find the % of components. I suppose you might approximate their relative strength compared to tap water by using the data I have posted, but personally I just trust the manufacturer's recommendations, and if I am selling prints I would confirm their sayings with a residual hypo test solution.

[Paul Howell]

Hypo eliminator is not all the same thing as a wash aid or hypo clearing bath. As I recall the Kodak version was amonina and hydrogen peroxide, it did not reduce wash time but eliminated hypo attached to paper fibers. As already mentioned the use of hypo eliminator was discouraged in the 70's as it the total elimination of hypo may not aid in archival process. I used the Kodak formula in the 60s, my prints from this period seem to have not suffered any ill effects, but who knows in a 100 years?

[Ryuji]

http://www.silvergrain.org/wiki/inde...le=Washing_aid

[Paul Howell]

Thanks for the link, very helpful. I dont know if rewashing my old prints will undo any of the effects of hypo eliminator I used in the 60s, the prints are now 40+ years old.