Pitfalls of De-Ionized Water in Photo Solutions?

[Gunfleet]

Thanks. Yes we do have both a dehumidifier and a tumble doer and both seem to me to out put what appears to be distilled water... But i have no scientific knowledge hence my question. I always process in tap water which doesn't seem to be a problem except i would quite like to use something 'cleaner' at the last wash stage.

 

[Photo Engineer]

Oh, my, what holds atomic bromine back then?

Atomic bromine does not form in film, therefore it need not be held back. However, based on the equilibrium expected, if it were ever to form it would be "eaten" up by the rest of the chemistry.

[AgBr] <> [Ag+] + [Br-] does take place upon exposure and during keeping and Br- can move on but is usually in such minute specs at exposure time it is odorless. The PKSP holds Bromide back and its great reactivity holds it back (were it to ever form which it does not easily do) by reacting with other species. At such levels it has no detectable odor.

You must remember that AgBr emulsions are yellowish gelatin suspensions and are totally odorless even under light and at high concentration.

PE

 

[Europan]

Thank you for contemplating the thing

When I expose a 100-ft. roll of 35-mm. movie film, I have about a milligram of free bromine in every frame of 18 by 24 mm. I start with 8 grams of silver salts per square meter of a black-and-white film, 90 percent of them silver bromide. Half of it shall be developable to densities between, say log 0.2 and log 2.0. The hundred-foot portion will hold 1600 frames so that I have 1.6 grams of bromine. A thousand-foot roll such as used in a Mitchell magazine will yield 16 grams.

Hundred feet of 16-mm. film contain 4000 frames of 7.5 by 10 mm, more or less. That is 0.3 square meters film surface. A 20-second shot at 24 frames per second consists of 480 frames, 0.036 square meters. Again 8 grams of silver salts per square meter, 90 % silver bromide, half of that usable pictorially: 0.13 grams of bromine.

An 8" by 10" sheet of Plus-X negative film, I presume 5 grams of silver salts per square meter, has 0.048 square meters image area, about 0.1 gram of bromine per click.

No odour? I remember well the smell of freshly exposed print stock, black and white and colour, when I loaded the developing machine mags as employee and at my own lab. What would the perfume be?

 

[Photo Engineer]

No odor from Bromine! The Bromine is tied up as Silver Bromide salts and in the developer as Sodium or Potassium Bromide salts. None of these are volatile. The ability of Bromide salts to form a gas is so close to zero, that it is expressed in very small terms. It melts at 432C and boils at 1502C. You might begin to smell it about 432C and you would certainly smell it at 1502 C if you were still alive then. And, it would be mixed with Silver. It has to be to retain a neutral charge. So, you would smell Silver.

PE

 

[Gerald C Koch]

People confuse elements and their ions. They are not the same. For example sodium metal is very reactive and can cause fires. Chlorine is a poisonous gas. But sodium ions and chloride ions are found in table salt and are pretty innocuous.

Elemental bromine has a very distinctive smell. The fact that film may smell does not mean that bromine is present. The name bromine comes from the Greek bromos meaning stench. Once you have smelled the real thing you will not forget it.

 

[Europan]

I know the stench. Still, silver halide crystals or grains hit by light have discharged ions, that is elementary silver and elementary bromine, somewhere within. I can well imagine both elements becoming absorbed, even reacting with some elements or compounds present. Basically, as long as not all of a crystal is decomposed under the influence of radiation, it may continue to exist in its outer form.

Nuclei have been spoken of, tiny amounts of silver where the developing agents enter and get absorbed, literally built into the growing silver wool. But where remains the bromine? I’m not a chemist, if I were, I should know whether Br is crouching there or Br2. Also am I not familiar with the reactivity of Br amid I, Cl, and H. I guess the further reactions of Br in situ are known. Would have been fine to read about such here.

 

[Photo Engineer]

Well, the latent image that forms is comprised of as little as 3 silver atoms which then means that 3 atoms of bromide ion are floating around there. That is not very much. No odor.

Now, during development, you get AgBr + HQ -> Ag + Q + Br- and the Br- goes on to form salts with the alkali metals in the developer.

PE