Alternatives to Brown Plastic Jugs

Dan Quinn wrote:

Patrick Gainer wrote

The amount of air that is in the water...

(that would be .00845 grams of oxygen at saturation per liter)

...you use to mix your solutions
may be enough to reduce considerably the capacity of your developer.
This is especially true of ascorbate developers. 0.09 grams of oxygen
will oxidize 1 gram of ascorbic acid,

That be the case 1/10th of that gram will be oxidized when placed in
one liter of oxygen saturated water or 1/100 will be oxidized if ten
grams be placed in the same water.

and sulfite will not prevent it.
Neither will storage at low pH.

The two togeather will preserve ascorbic acid if the solution ph
is below 5.5.

1 gram of ascorbic acid is also capable of reducing enough
silver halide to produce an average density of 1 on 38 rolls of film
or 8X10 sheets, ...

I've real doubts about that. I've not actually put 38 rolls or
that many 8x10s through a developer with no more than one gram of
ascorbic acid as the developing agent.

It wouldn't make any difference if you had 10 grams of ascorbic acid. 1
of those grams is still used up by 38 rolls of film. None of the
phenidone or metol is used up. So which is the developing agent? The
phenidone alone will certainly not do that.
In fact I don't even consider ascorbic acid a developing agent. If
the ph is way way up it will reduce some silver. I think it is best
likend to hydroquinone for it's regenerative function. That is
it reduces the other or other developing agent/agents present.

You can look at it that way if you want, but it is wrong. It is not
proper to consider the ascorbic acid or hydroquinone as only
regenerating the phenidone. The phenidone or metol activates the
hydroquinone or ascorbate, which do the actual work. In the case of
ascorbates, the product of reaction with any so-called "free radical" is
dehydroascorbic acid. The developer solution becomes more acidic as
development of silver halide progesses. It also becomes more acidic as
oxygen is converted to water by the two hydrogen atoms it gets from
ascorbic acid or any ascorbate. This occurs at pH of 3 or so and higher.
How much ascorbate is in Xtol diluted 1+2?

Sulfite is required for the synergism between hydroquinone and other
agents, as one of the intermediate products is hydroquinone
monosulfonate. Sulfit is not required for the synergism between
ascorbates and othe agents. The mechanism is not the same as for
hydroquinone.

I think the solubility of oxygen in water is greater than 0.09
grams/liter. The amount of silver needed to cover a given area to a
given optical or photographic density is well known for old emulsions.
It is probably even less for the tabular grained ones. 0.0001 grams of
silver per cm square per unit density is a conservative number for the
calculations I did. 1 molecular weight of ascorbic acid will be oxidized
to dehydroascorbic acid by 1 atomic weight of oxygen. If there are any
other things in the water, such as bacteria, they may as well oxidize
some ascorbate. Iron is known to catalyze the oxidation process.

The easiest way to avoid some of these real or imagined problems that I
have found is to keep the stock solution inactive until you want to
develop film by dissolving it in a glycol.


A way to scavenge
all oxygen from the solution right from the start is needed.

For most solutions I'd consider that more ado about nearly
nothing. Some very dilute solutions should be striped of that
.00845 gram of oxygen.
The usuall way to scavange that O2 is a pinch of sulfite first
than the whatever. For ascorbic acid try the bisulfite. I've
found the two to be harmonious.
Stirring of solutions which are subject to oxidation must be
minimized. Dan

Patrick Gainer wrote:

Dan Quinn wrote:

Patrick Gainer wrote

The amount of air that is in the water...

(that would be .00845 grams of oxygen at saturation per liter)

...you use to mix your solutions
may be enough to reduce considerably the capacity of your developer.
This is especially true of ascorbate developers. 0.09 grams of oxygen
will oxidize 1 gram of ascorbic acid,

That be the case 1/10th of that gram will be oxidized when placed in
one liter of oxygen saturated water or 1/100 will be oxidized if ten
grams be placed in the same water.

and sulfite will not prevent it.
Neither will storage at low pH.

The two togeather will preserve ascorbic acid if the solution ph
is below 5.5.

1 gram of ascorbic acid is also capable of reducing enough
silver halide to produce an average density of 1 on 38 rolls of film
or 8X10 sheets, ...

I've real doubts about that. I've not actually put 38 rolls or
that many 8x10s through a developer with no more than one gram of
ascorbic acid as the developing agent.

It wouldn't make any difference if you had 10 grams of ascorbic acid. 1
of those grams is still used up by 38 rolls of film. None of the
phenidone or metol is used up. So which is the developing agent? The
phenidone alone will certainly not do that.
In fact I don't even consider ascorbic acid a developing agent. If
the ph is way way up it will reduce some silver. I think it is best
likend to hydroquinone for it's regenerative function. That is
it reduces the other or other developing agent/agents present.

You can look at it that way if you want, but it is wrong. It is not
proper to consider the ascorbic acid or hydroquinone as only
regenerating the phenidone. The phenidone or metol activates the
hydroquinone or ascorbate, which do the actual work. In the case of
ascorbates, the product of reaction with any so-called "free radical" is
dehydroascorbic acid. The developer solution becomes more acidic as
development of silver halide progesses. It also becomes more acidic as
oxygen is converted to water by the two hydrogen atoms it gets from
ascorbic acid or any ascorbate. This occurs at pH of 3 or so and higher.
How much ascorbate is in Xtol diluted 1+2?

Sulfite is required for the synergism between hydroquinone and other
agents, as one of the intermediate products is hydroquinone
monosulfonate. Sulfit is not required for the synergism between
ascorbates and othe agents. The mechanism is not the same as for
hydroquinone.

I think the solubility of oxygen in water is greater than 0.09
grams/liter. The amount of silver needed to cover a given area to a
given optical or photographic density is well known for old emulsions.
It is probably even less for the tabular grained ones. 0.0001 grams of
silver per cm square per unit density is a conservative number for the
calculations I did. 1 molecular weight of ascorbic acid will be oxidized
to dehydroascorbic acid by 1 atomic weight of oxygen. If there are any
other things in the water, such as bacteria, they may as well oxidize
some ascorbate. Iron is known to catalyze the oxidation process.

The easiest way to avoid some of these real or imagined problems that I
have found is to keep the stock solution inactive until you want to
develop film by dissolving it in a glycol.


A way to scavenge
all oxygen from the solution right from the start is needed.

For most solutions I'd consider that more ado about nearly
nothing. Some very dilute solutions should be striped of that
.00845 gram of oxygen.
The usuall way to scavange that O2 is a pinch of sulfite first
than the whatever. For ascorbic acid try the bisulfite. I've
found the two to be harmonious.
Stirring of solutions which are subject to oxidation must be
minimized. Dan
Sorry. One of the hazards of the slide rule is decimal point errors. I
think the solubility of oxygen in cold water is about 4.5 cc per liter.
That would be about 0.009 grams at atmospheric pressure.

I don't want to use any sulfite in my ascorbate developers, for other
reasons. Perhaps a tiny bit of hydroquinone would be a more appropriate
scavenger than sulfite, since it has practically no developing power of
its own at low pH and low concentration, and is not superadditive with
either ascorbic acid or phenidone without sulfite. Better yet, a tiny
bit of pyro. But that would increase the hazard slightly, enough to
scare off many people.

Patrick Gainer wrote

Dan Quinn wrote:

(that would be .00845 grams of oxygen at saturation per liter)
NOT COLD but 20*C

The two togeather will preserve ascorbic acid if the solution ph
is below 5.5.
Bisulfite and a low ph.
That is according to the book. I've some mixed up and now ageing.
I'll likely test again in a few weeks.

In fact I don't even consider ascorbic acid a developing agent. If
the ph is way way up it will reduce some silver. I think it is best
likend to hydroquinone for it's regenerative function. That is
it reduces the other or other developing agent/agents present.

The phenidone or metol activates the
hydroquinone or ascorbate, which do the actual work.

THAT will be news to quite a few! Dan

A way to scavenge
all oxygen from the solution right from the start is needed.

For most solutions I'd consider that more ado about nearly
nothing. Some very dilute solutions should be striped of that
.00845 gram of oxygen.
The usuall way to scavange that O2 is a pinch of sulfite first
than the whatever. For ascorbic acid try the bisulfite. I've
found the two to be harmonious.
Stirring of solutions which are subject to oxidation must be
minimized. Dan

Dan Quinn wrote:

Patrick Gainer wrote

Dan Quinn wrote:

(that would be .00845 grams of oxygen at saturation per liter)
NOT COLD but 20*C

The two togeather will preserve ascorbic acid if the solution ph
is below 5.5.
Bisulfite and a low ph.
That is according to the book. I've some mixed up and now ageing.
I'll likely test again in a few weeks.

Which book?
In fact I don't even consider ascorbic acid a developing agent. If
the ph is way way up it will reduce some silver. I think it is best
likend to hydroquinone for it's regenerative function. That is
it reduces the other or other developing agent/agents present.

The phenidone or metol activates the
hydroquinone or ascorbate, which do the actual work.

THAT will be news to quite a few!

But not to the authors of "Theory of the Photographic Science"
Pat

A way to scavenge
all oxygen from the solution right from the start is needed.

For most solutions I'd consider that more ado about nearly
nothing. Some very dilute solutions should be striped of that
.00845 gram of oxygen.
The usuall way to scavange that O2 is a pinch of sulfite first
than the whatever. For ascorbic acid try the bisulfite. I've
found the two to be harmonious.
Stirring of solutions which are subject to oxidation must be
minimized. Dan

Patrick Gainer wrote

The two togeather will preserve ascorbic acid if the solution ph
is below 5.5.
Bisulfite and a low ph.

That is according to the book. I've some mixed up and now ageing.
I'll likely test again in a few weeks.
Dan

Which book?

In a manor of speaking, a book. I found that information via
Google. The paper dealt, IIRC, with various anti-oxidates used with
pharmaceuticals. I'll see if I can find it. Dan

Dan Quinn wrote:

Patrick Gainer wrote

The two togeather will preserve ascorbic acid if the solution ph
is below 5.5.
Bisulfite and a low ph.

That is according to the book. I've some mixed up and now ageing.
I'll likely test again in a few weeks.
Dan

Which book?

In a manor of speaking, a book. I found that information via
Google. The paper dealt, IIRC, with various anti-oxidates used with
pharmaceuticals. I'll see if I can find it. Dan
I should have said my idea of ascorbic acid as a developing agent would
not be surprising to the authors "Theory of the Photographic Process."
This what happens when I trust my 76 yeaar old memory. I believe in the
hereafter. When I set out to get something, I get where I think it is,
but cannot remember what I am here after

Patrick Gainer wrote

Dan Quinn wrote:

The two togeather will preserve ascorbic acid if the solution ph
is below 5.5; bisulfite and a low ph.
That is according to the book. I've some mixed up and now ageing.
I'll likely test again in a few weeks.


Which book?


I've yet to find that article.
I may have made an error. A ph of 5.5 may be the
equallibrian ph.
BTW, have you tested ascorbic by itself for keeping qualities?
With it's ph in solution well below 3, I think it might do well. I've
some in Polycone sealed glass bottles and intend to test it. Dan