Not using a stop bath when developing film?

Andrew McCall wrote in message ...
Hi Folks,

The college I go to have recently decided not to use a stop bath when
developing film as the gasses it produces seems to agitate some students
with asthma.
...
I will probably be developing my film at home now, but I was wondering
if I have to, will developing at college with no stop bath have an
effect on my negatives.

Use water as a stop bath instead. While it doesn't
neutralize the alkaline developer the way an acid
stop does, the sudden sharp dilution of the developer
has much the same effect.

Or use a citric acid stop bath, instead of acetic acid.
Acetic acid smells (vinegar). Citric acid doesn't.

Laura Halliday VE7LDH "Que les nuages soient notre
Grid: CN89mg pied a terre..."
ICBM: 49 16.05 N 122 56.92 W - Hospital/Shafte

Uranium Committee wrote:

Tom Phillips wrote in message ...
Uranium Committee wrote:

The problem as I see it is that when the stop bath hits the film in a
tank it may do so unevenly, causing some streaking. I did occasionally
experience this.

You must have been naked and hallucinating in your darkroom...

By flushing the developer out with water under a
little pressure or flow, one is assured of a kinder, gentler end to
development. I simply leave the tank full of developer, and begin
pouring water in through a funnel into the neck of the Paterson tank.
This way, the water replaces the devloper, and the developer is not
left clinging to the film in uneven layers, which can happen when the
tank is emptied and allowed to drain before the next step. This
developer clinging to the film can cause uneven development.

Troll nonsense. Developer simply continues to develop
until exhausted. Doesn't cause "uneven" development,
since the negative density controls the effect.

Uneven coating of developer will certainly cause streaking, as would
occur when stop bath is splashed onto the film that still has areas
that are wet with developer.

One does not "splash." One immerses.

Also,
with either a water rinse or an actual stop bath diffusion
should occur at the same rate. Being acidic, stop bath works
quicker by neutralizing developer _alkalinity_ and thus has
the advantage of preventing carry over.

I rinse the film thoroughly with lots of water that displaces and
replaces the developer over about 7 seconds. The point is that the
change-over is more uniform, because the water does not arrest
development instantly, but smoothly.

Sorry. Diffusion takes at least 30 seconds and the
developer continues to be active in thin (less dense)
areas of the negative. Development in the emulsion is
not arrested ("smoothly" or any other way) by dilution,
but simply continues to develop until exhausted.

Uranium Committee wrote:

Tom Phillips wrote in message ...
Uranium Committee wrote:

The problem as I see it is that when the stop bath hits the film in a
tank it may do so unevenly, causing some streaking. I did occasionally
experience this.

You must have been naked and hallucinating in your darkroom...

By flushing the developer out with water under a
little pressure or flow, one is assured of a kinder, gentler end to
development. I simply leave the tank full of developer, and begin
pouring water in through a funnel into the neck of the Paterson tank.
This way, the water replaces the devloper, and the developer is not
left clinging to the film in uneven layers, which can happen when the
tank is emptied and allowed to drain before the next step. This
developer clinging to the film can cause uneven development.

Troll nonsense. Developer simply continues to develop
until exhausted. Doesn't cause "uneven" development,
since the negative density controls the effect.

Uneven coating of developer will certainly cause streaking, as would
occur when stop bath is splashed onto the film that still has areas
that are wet with developer.

One does not "splash." One immerses.

Also,
with either a water rinse or an actual stop bath diffusion
should occur at the same rate. Being acidic, stop bath works
quicker by neutralizing developer _alkalinity_ and thus has
the advantage of preventing carry over.

I rinse the film thoroughly with lots of water that displaces and
replaces the developer over about 7 seconds. The point is that the
change-over is more uniform, because the water does not arrest
development instantly, but smoothly.

Sorry. Diffusion takes at least 30 seconds and the
developer continues to be active in thin (less dense)
areas of the negative. Development in the emulsion is
not arrested ("smoothly" or any other way) by dilution,
but simply continues to develop until exhausted.

Tom Phillips wrote in message ...
Uranium Committee wrote:

Tom Phillips wrote in message ...
Uranium Committee wrote:

The problem as I see it is that when the stop bath hits the film in a
tank it may do so unevenly, causing some streaking. I did occasionally
experience this.

You must have been naked and hallucinating in your darkroom...

By flushing the developer out with water under a
little pressure or flow, one is assured of a kinder, gentler end to
development. I simply leave the tank full of developer, and begin
pouring water in through a funnel into the neck of the Paterson tank.
This way, the water replaces the devloper, and the developer is not
left clinging to the film in uneven layers, which can happen when the
tank is emptied and allowed to drain before the next step. This
developer clinging to the film can cause uneven development.

Troll nonsense. Developer simply continues to develop
until exhausted. Doesn't cause "uneven" development,
since the negative density controls the effect.

Uneven coating of developer will certainly cause streaking, as would
occur when stop bath is splashed onto the film that still has areas
that are wet with developer.

One does not "splash." One immerses.

As the tank fills, it splashes a little.


Also,
with either a water rinse or an actual stop bath diffusion
should occur at the same rate. Being acidic, stop bath works
quicker by neutralizing developer _alkalinity_ and thus has
the advantage of preventing carry over.

I rinse the film thoroughly with lots of water that displaces and
replaces the developer over about 7 seconds. The point is that the
change-over is more uniform, because the water does not arrest
development instantly, but smoothly.

Sorry. Diffusion takes at least 30 seconds and the
developer continues to be active in thin (less dense)
areas of the negative. Development in the emulsion is
not arrested ("smoothly" or any other way) by dilution,
but simply continues to develop until exhausted.

That's exactly what I mean by 'smoothly'. I begin filling the tank
with water about 45 seconds before development is to end. The
deevloper is NOT poured out of the tank; the water simply displaces
it.

(Uranium Committee) wrote

That's exactly what I mean by 'smoothly'. I begin filling the tank
with water about 45 seconds before development is to end. The
developer is NOT poured out of the tank; the water simply displaces
it.


And the film comes out alive? Imagine that! Tell me then
what's all this talk of instantly stoping development? Just so
much baloney? Some contributors to this NG imply by their posts
that an instant stop is THE virtuous stop. Dan

On Thu, 11 Nov 2004 00:03:28 +0000, Andrew McCall
wrote:

Hi Folks,

The college I go to have recently decided not to use a stop bath when
developing film as the gasses it produces seems to agitate some students
with asthma.

Can anyone tell me why it would do this to the asthma suffers, ie. what
gasses are given off by the stop bath?

....


nov2304 from Lloyd Erlick,

I think the college would do well to switch to non-acid
film and print processing for black and white. This
would eliminate any gasses that the common darkroom
might emit.

The main gasses and 'fumes', not to mention stenches,
that afflict the darkroom are acetic acid (smells like
vinegar), sulfur dioxide (bites nose sharply), and
hydrogen sulfide (rotten egg smell). If acid is removed
from the darkroom, none of these can come into
existence.

The mechanism by which sulfur dioxide and hydrogen
sulfide harm humans (and no doubt asthma sufferers
react to much less exposure than it takes to harm a
non-asthmatic) is: both gasses dissolve readily in
water. Human lungs and breathing passages are coated
with mucous, which contains a large proportion of
water. Thus, the gas dissolves in water in the lungs,
whereupon it reacts to form sulfurous acid. The lungs
are full of air, containing lots of oxygen, and
sulfurous acid oxidizes readily, to form sulfuric acid.
If enough gas is present in the atmosphere being
breathed, enough acid will form to damage tissue.

A very important point about hydrogen sulfide: humans
can detect the odor of extremely small amounts. The
smell is very distinctive, and we detect it at levels
far below dangerous. However, it is possible to ignore
the warning and become complacent if we stop detecting
the odor. This can be a very important danger sign,
because it appears the action of hydrogen sulfide upon
the olfactory sense organ is numbing or deadening
(probably the effect of sulfuric acid). People have
died in mines because they thought the gas had gone
away, when in fact their own sensory input had gone.

If people are sensitive enough that even ammonia must
be eliminated, it only means that selenium toner cannot
be used or must be used with special care. Ammonia is
very easy to deal with by ventilation, and also it's
easy to keep selenium toner under cover except for the
moment needed to put the sheet into it, (or pour it
onto the sheet).

I have some articles on my website (under the technical
heading, in the table of contents) about smell/fume
abatement in the darkroom, as well as the single tray
method of processing prints and odorless fixers. I
think anyone with asthma who would like to work in the
darkroom should look them over.

regards,
--le
________________________________
Lloyd Erlick Portraits, Toronto.
voice: 416-686-0326
email:
net: www.heylloyd.com
________________________________


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On Thu, 11 Nov 2004 00:03:28 +0000, Andrew McCall
wrote:

Hi Folks,

The college I go to have recently decided not to use a stop bath when
developing film as the gasses it produces seems to agitate some students
with asthma.

Can anyone tell me why it would do this to the asthma suffers, ie. what
gasses are given off by the stop bath?

....


nov2304 from Lloyd Erlick,

I think the college would do well to switch to non-acid
film and print processing for black and white. This
would eliminate any gasses that the common darkroom
might emit.

The main gasses and 'fumes', not to mention stenches,
that afflict the darkroom are acetic acid (smells like
vinegar), sulfur dioxide (bites nose sharply), and
hydrogen sulfide (rotten egg smell). If acid is removed
from the darkroom, none of these can come into
existence.

The mechanism by which sulfur dioxide and hydrogen
sulfide harm humans (and no doubt asthma sufferers
react to much less exposure than it takes to harm a
non-asthmatic) is: both gasses dissolve readily in
water. Human lungs and breathing passages are coated
with mucous, which contains a large proportion of
water. Thus, the gas dissolves in water in the lungs,
whereupon it reacts to form sulfurous acid. The lungs
are full of air, containing lots of oxygen, and
sulfurous acid oxidizes readily, to form sulfuric acid.
If enough gas is present in the atmosphere being
breathed, enough acid will form to damage tissue.

A very important point about hydrogen sulfide: humans
can detect the odor of extremely small amounts. The
smell is very distinctive, and we detect it at levels
far below dangerous. However, it is possible to ignore
the warning and become complacent if we stop detecting
the odor. This can be a very important danger sign,
because it appears the action of hydrogen sulfide upon
the olfactory sense organ is numbing or deadening
(probably the effect of sulfuric acid). People have
died in mines because they thought the gas had gone
away, when in fact their own sensory input had gone.

If people are sensitive enough that even ammonia must
be eliminated, it only means that selenium toner cannot
be used or must be used with special care. Ammonia is
very easy to deal with by ventilation, and also it's
easy to keep selenium toner under cover except for the
moment needed to put the sheet into it, (or pour it
onto the sheet).

I have some articles on my website (under the technical
heading, in the table of contents) about smell/fume
abatement in the darkroom, as well as the single tray
method of processing prints and odorless fixers. I
think anyone with asthma who would like to work in the
darkroom should look them over.

regards,
--le
________________________________
Lloyd Erlick Portraits, Toronto.
voice: 416-686-0326
email:
net: www.heylloyd.com
________________________________


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Lloyd Usenet-Erlick wrote:

On Thu, 11 Nov 2004 00:03:28 +0000, Andrew McCall
wrote:

Hi Folks,

The college I go to have recently decided not to use a stop bath when
developing film as the gasses it produces seems to agitate some students
with asthma.

Can anyone tell me why it would do this to the asthma suffers, ie. what
gasses are given off by the stop bath?

...

nov2304 from Lloyd Erlick,

I think the college would do well to switch to non-acid
film and print processing for black and white. This
would eliminate any gasses that the common darkroom
might emit.

The main gasses and 'fumes', not to mention stenches,
that afflict the darkroom are acetic acid (smells like
vinegar), sulfur dioxide (bites nose sharply), and
hydrogen sulfide (rotten egg smell). If acid is removed
from the darkroom, none of these can come into
existence.

The mechanism by which sulfur dioxide and hydrogen
sulfide harm humans (and no doubt asthma sufferers
react to much less exposure than it takes to harm a
non-asthmatic) is: both gasses dissolve readily in
water. Human lungs and breathing passages are coated
with mucous, which contains a large proportion of
water. Thus, the gas dissolves in water in the lungs,
whereupon it reacts to form sulfurous acid. The lungs
are full of air, containing lots of oxygen, and
sulfurous acid oxidizes readily, to form sulfuric acid.
If enough gas is present in the atmosphere being
breathed, enough acid will form to damage tissue.


This is a very informative description. However, I
think also overstated for the typical darkroom. I know
of no photographer who has suffered adverse damage or
illness from exposure to typical mild acid chemistry.
Ansel Adams, Richard Avedon, etc. etc., lived long and
healthy lives and died of old age William Henry
Jackson handled photo chemicals from the collodion
era to the modern era (1870s to early 20th century)
and enjoyed a remarkably healthy life of over 90 years.

Now, some (as yourself) may be more sensitive to mild
acid fumes and byproducts than most. I have no problem
with offering alternate methods. But you make it sound
as if this is a serious health hazard and statistically
significant. It's not. Acid rain is more of a hazard; it
kills trees and fish but isn't very harmful to humans.

I think it should be pointed out the typical darkroom
using an acid process (especially with rapid fix) is
not a unhealthy environment and if the fumes bother
more sensitive people it's an indication the room in
fact has inadequate _ventilation_, which for a school
darkroom probably violates OSHA standards.

What bothers me about most of these discussions is some
who religiously advocate alkaline vs acid also claim
a virtue of alkaline is no ventilation is needed. _Any_
darkroom should receive a minimum of about 6-8 air changes
per hour (once every ten minutes, and if a commerical or
school darkroom probably more. This will eliminate most
if not all chemistry issues unless one actually sticks
their nose in the stop/fixer.

A very important point about hydrogen sulfide: humans
can detect the odor of extremely small amounts. The
smell is very distinctive, and we detect it at levels
far below dangerous. However, it is possible to ignore
the warning and become complacent if we stop detecting
the odor. This can be a very important danger sign,
because it appears the action of hydrogen sulfide upon
the olfactory sense organ is numbing or deadening
(probably the effect of sulfuric acid). People have
died in mines because they thought the gas had gone
away, when in fact their own sensory input had gone.

If people are sensitive enough that even ammonia must
be eliminated, it only means that selenium toner cannot
be used or must be used with special care. Ammonia is
very easy to deal with by ventilation, and also it's
easy to keep selenium toner under cover except for the
moment needed to put the sheet into it, (or pour it
onto the sheet).

I have some articles on my website (under the technical
heading, in the table of contents) about smell/fume
abatement in the darkroom, as well as the single tray
method of processing prints and odorless fixers. I
think anyone with asthma who would like to work in the
darkroom should look them over.

regards,
--le
________________________________
Lloyd Erlick Portraits, Toronto.
voice: 416-686-0326
email:
net: www.heylloyd.com
________________________________

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Lloyd Usenet-Erlick wrote:

On Thu, 11 Nov 2004 00:03:28 +0000, Andrew McCall
wrote:

Hi Folks,

The college I go to have recently decided not to use a stop bath when
developing film as the gasses it produces seems to agitate some students
with asthma.

Can anyone tell me why it would do this to the asthma suffers, ie. what
gasses are given off by the stop bath?

...

nov2304 from Lloyd Erlick,

I think the college would do well to switch to non-acid
film and print processing for black and white. This
would eliminate any gasses that the common darkroom
might emit.

The main gasses and 'fumes', not to mention stenches,
that afflict the darkroom are acetic acid (smells like
vinegar), sulfur dioxide (bites nose sharply), and
hydrogen sulfide (rotten egg smell). If acid is removed
from the darkroom, none of these can come into
existence.

The mechanism by which sulfur dioxide and hydrogen
sulfide harm humans (and no doubt asthma sufferers
react to much less exposure than it takes to harm a
non-asthmatic) is: both gasses dissolve readily in
water. Human lungs and breathing passages are coated
with mucous, which contains a large proportion of
water. Thus, the gas dissolves in water in the lungs,
whereupon it reacts to form sulfurous acid. The lungs
are full of air, containing lots of oxygen, and
sulfurous acid oxidizes readily, to form sulfuric acid.
If enough gas is present in the atmosphere being
breathed, enough acid will form to damage tissue.


This is a very informative description. However, I
think also overstated for the typical darkroom. I know
of no photographer who has suffered adverse damage or
illness from exposure to typical mild acid chemistry.
Ansel Adams, Richard Avedon, etc. etc., lived long and
healthy lives and died of old age William Henry
Jackson handled photo chemicals from the collodion
era to the modern era (1870s to early 20th century)
and enjoyed a remarkably healthy life of over 90 years.

Now, some (as yourself) may be more sensitive to mild
acid fumes and byproducts than most. I have no problem
with offering alternate methods. But you make it sound
as if this is a serious health hazard and statistically
significant. It's not. Acid rain is more of a hazard; it
kills trees and fish but isn't very harmful to humans.

I think it should be pointed out the typical darkroom
using an acid process (especially with rapid fix) is
not a unhealthy environment and if the fumes bother
more sensitive people it's an indication the room in
fact has inadequate _ventilation_, which for a school
darkroom probably violates OSHA standards.

What bothers me about most of these discussions is some
who religiously advocate alkaline vs acid also claim
a virtue of alkaline is no ventilation is needed. _Any_
darkroom should receive a minimum of about 6-8 air changes
per hour (once every ten minutes, and if a commerical or
school darkroom probably more. This will eliminate most
if not all chemistry issues unless one actually sticks
their nose in the stop/fixer.

A very important point about hydrogen sulfide: humans
can detect the odor of extremely small amounts. The
smell is very distinctive, and we detect it at levels
far below dangerous. However, it is possible to ignore
the warning and become complacent if we stop detecting
the odor. This can be a very important danger sign,
because it appears the action of hydrogen sulfide upon
the olfactory sense organ is numbing or deadening
(probably the effect of sulfuric acid). People have
died in mines because they thought the gas had gone
away, when in fact their own sensory input had gone.

If people are sensitive enough that even ammonia must
be eliminated, it only means that selenium toner cannot
be used or must be used with special care. Ammonia is
very easy to deal with by ventilation, and also it's
easy to keep selenium toner under cover except for the
moment needed to put the sheet into it, (or pour it
onto the sheet).

I have some articles on my website (under the technical
heading, in the table of contents) about smell/fume
abatement in the darkroom, as well as the single tray
method of processing prints and odorless fixers. I
think anyone with asthma who would like to work in the
darkroom should look them over.

regards,
--le
________________________________
Lloyd Erlick Portraits, Toronto.
voice: 416-686-0326
email:
net: www.heylloyd.com
________________________________

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