Not using a stop bath when developing film?

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?

What are the effects on processing when skipping the stop bath? We are
using relatively slow developers like Agfa Rodinal and Ilford Ilfotec DD-X.

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.

Thanks,

Andrew McCall

"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.

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

What are the effects on processing when skipping the stop
bath? We are using relatively slow developers like Agfa
Rodinal and Ilford Ilfotec DD-X.

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.

Thanks,

Andrew McCall

Stop bath is a mild solution of Acetic acid, about half
the strength of white vinegar. It can react with the sodium
sulfite in developers to release a small amount of Sulfur
dioxide gas. Sulfur dioxide has a sharp odor and can trigger
asthma in those afflicted. It can also release Carbon
dioxide gas when developers with carbonates are used. There
are very few current packaged film developers with carbonate
in them but most paper developers have it. Carbon dioxide in
these very small amounts is not dangerous or irritating. Nor
will it cause pin-holes in modern emulsions.
Stop bath is important in stopping development at a
definite point but a plain water stop can be used provided
its thorough. It should really be a short wash. Thoroughly
agitate the film in the water for a minute or more.
Carried over developer will react with the acid in the
fixing bath the same way it does with the stop bath.
Generally, acid fixing baths do emmit some sulphur dioxide
gas.
The use of a non hardening fixing bath or a neutral bath
will eliminate this. Kodak Rapid Fixer with Hardener is
reasonably low odor if the hardener is not added. Agfa
Universal Fixer, used in color processes, is a neutral pH
non-hardening rapid fixer.
Odor free stop baths can be made using Citric acid and
Sodium bisulfite or metabisulfite. Citric acid stop baths
should not be used with hardening fixing baths because the
citric acid tends to cause precipitation of the alum
hardener. Ilford packaged stop bath concentrate is made from
citric acid but citric is also available cheaply from health
food stores and for use in home canning. Use about 15 grams
per liter for stop bath. This is also about the right amount
of Sodium Bisulfite or metabisulfite. Most Sodium bisulfite
is actually metabisulfite, they are identical in action in
photo solutions.
Good ventillation is a necessity for a darkroom.


--
---
Richard Knoppow
Los Angeles, CA, USA

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?

What are the effects on processing when skipping the stop bath? We are
using relatively slow developers like Agfa Rodinal and Ilford Ilfotec DD-X.

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.

Thanks,

Andrew McCall


nov1104 from Lloyd Erlick,

Using plain tap water in place of an acid stop bath is
common practice. It requires a certain care, but is
easy and effective.

Personally, I used to enjoy the smell of stop bath. I
still like vinegar on my french fries. But eight or ten
hours around stop bath, many times, has made me hate
all smells in my darkroom. I like an odor free darkroom
now.

My website has articles about my quest for a smell free
zone in my darkroom. The one about non-acid print
processing might be of interest (applies to film, too,
more or less.) Look under 'technical' in the table of
contents.

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




----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups
---= East/West-Coast Server Farms - Total Privacy via Encryption =---

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?

What are the effects on processing when skipping the stop bath? We are
using relatively slow developers like Agfa Rodinal and Ilford Ilfotec DD-X.

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.


Ilford makes a odorless stopbath, which I think is based on citric acid
rather then acetic acid. Technically you still have a stop bath, it's
just water instead of a diluted vinegar. What I usually did was double
the length of the stop, and then reduce the capacity of the fixer to
half. I never used a stop bath with film, but 3 20 second water soaks,
and then used the fixer 1 shot. Never had a problem.

W

My own practice is to use a water rinse when processing film between the
developer and fix, since this is one-shot it will stop development almost as
effectively as an acid stop.

For printing in trays, developer carry-over will render a water stop bath
alkaline in short order at which point you are no longer stopping
development but doing stand development in a two bath developer! Did this
by accident one time (diluted Dektol stock 1+31 in my stop bath tray instead
of acetic acid--really tired that night) and got some interesting results,
if you leave prints in the diluted "stop" tray for extended periods of time,
sort of Sabattier but weak and orange-ish highlights, standard practice in
this darkroom was to let prints pile up in the stop bath and then fix them
in batches before moving out of the darkroom to the big Pako Washer.

--
darkroommike

----------
"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.

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

What are the effects on processing when skipping the stop bath? We are
using relatively slow developers like Agfa Rodinal and Ilford Ilfotec
DD-X.

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.

Thanks,

Andrew McCall

In article , The Wogster wrote:

I never used a stop bath with film, but 3 20 second water soaks,
and then used the fixer 1 shot. Never had a problem.

The use of a stop bath is really not needed for film, in fact there have
been "monobath" (combined developer/fixer) products on the market and
Edwal used to include instructions on how to use their developers
as monobaths.

The main reason to use one is to force development to end at a specific time
so that the results are the same, but using the same rinse procedure will
each time do the same thing (with slightly different results).

It's also to keep the alkeline developer from mixing with the acid fixer.
The acid in the fixer acts as an emulsion hardner. Some fixers include
it, some include it as an option (remember the two bottle kodak rapid
fixer with hardner?) and some don't have it at all.

Geoff.

--
Geoffrey S. Mendelson, Jerusalem Israel
IL Voice: 972-544-608-069 IL Fax: 972-2-648-1443 U.S. Voice: 1-215-821-1838

In article , The Wogster wrote:

I never used a stop bath with film, but 3 20 second water soaks,
and then used the fixer 1 shot. Never had a problem.

The use of a stop bath is really not needed for film, in fact there have
been "monobath" (combined developer/fixer) products on the market and
Edwal used to include instructions on how to use their developers
as monobaths.

The main reason to use one is to force development to end at a specific time
so that the results are the same, but using the same rinse procedure will
each time do the same thing (with slightly different results).

It's also to keep the alkeline developer from mixing with the acid fixer.
The acid in the fixer acts as an emulsion hardner. Some fixers include
it, some include it as an option (remember the two bottle kodak rapid
fixer with hardner?) and some don't have it at all.

Geoff.

--
Geoffrey S. Mendelson, Jerusalem Israel
IL Voice: 972-544-608-069 IL Fax: 972-2-648-1443 U.S. Voice: 1-215-821-1838

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.


try this healthy combination:
rinse your film for about 60" in plain water.
It's ok, and it's what I do.
Never needed stop bath.

Ciao,
Stefano
--
Non è bello cio che è bello figuriamoci cio che è brutto!
Ed io imparo.

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.


try this healthy combination:
rinse your film for about 60" in plain water.
It's ok, and it's what I do.
Never needed stop bath.

Ciao,
Stefano
--
Non è bello cio che è bello figuriamoci cio che è brutto!
Ed io imparo.

"Geoffrey S. Mendelson" wrote in message
...
In article
, The
Wogster wrote:

I never used a stop bath with film, but 3 20 second water
soaks,
and then used the fixer 1 shot. Never had a problem.

The use of a stop bath is really not needed for film, in
fact there have
been "monobath" (combined developer/fixer) products on the
market and
Edwal used to include instructions on how to use their
developers
as monobaths.

The main reason to use one is to force development to end
at a specific time
so that the results are the same, but using the same rinse
procedure will
each time do the same thing (with slightly different
results).

It's also to keep the alkeline developer from mixing with
the acid fixer.
The acid in the fixer acts as an emulsion hardner. Some
fixers include
it, some include it as an option (remember the two bottle
kodak rapid
fixer with hardner?) and some don't have it at all.

Geoff.

--
Geoffrey S. Mendelson, Jerusalem Israel
IL Voice: 972-544-608-069 IL Fax: 972-2-648-1443 U.S.
Voice: 1-215-821-1838

Its not the acid in the fixing bath that does the
hardening. Common fixing baths use Potassium aluminum
sulfate, also known as White Alum, or just Alum. The alum
hardens the gelatin but works only over a fairly narrow
range of pH. The hardening remains at neutral pH but is
destroyed at much on the alkaline side of neutral. There are
other hardeners, mostly organic compounds, which are
effective hardeners in alkaline solution. These are common
in color processing.
Because the acid in an acid fixing bath reacts with the
thiosulfate and eventually decomposes it some means must be
provided to protect the thiosulfate. This is usually sodium
sulfite. The large amount of sulfite needed also tends to
prevent stains from the reaction products of carried over
developer.
Because modern stop baths were devised to work with or
without a stop bath they are heavily buffered by using a
combination of Acetic acid and Boric acid. This tends to
keep the pH of the bath in the right range for effective
hardening despite carried over developer or carried over
stop bath. This type of bath also tends to have less problem
from sludging of the hardener when the pH is off the right
value.
It should be noted that the ability of thiosulfate to fix
is independant of pH.
The odor from fixing baths is due to some decomposition
of the thiosufate by the acid. Making the bath less acid
will reduce the odor. Neutral fixing baths, essentially just
thiosulfate and sulfite, are very low odor.
Citric acid or sodium bisulfite or sodium metabisulfite
can be used for odorless stop baths. Citric acid is not
ideal for use with fixers using alum hardeners because it is
a sequestering agent for aluminum and will cause reduction
of hardening and may also cause sludging.
Many modern films do not require hardening so do not need
fixers which are acid. I seen no advantage whatever in
making a fixing bath alkaline but making neutral fixer is
fine. Also, the swelling of the emulsion will be less in a
neutral bath than in either an acid or alkaline bath.
There is an advantage in washing if the emulsion is
neutral when it it is washed. If an acid hardening fixer is
used a buffered sulfite wash aid, like Kodak Hypo Clearing
Agent, will adjust the pH to neutral and also eliminate the
binding effect of the alum on thiosulfate and fixer reaction
products. Wash times when the emulsion is treated in such a
bath are the same regardless of the type of fixing bath
used. In addition the sulfite acts as an ion exchanger for
thiosulfate so the wash is very much accelerated over what
one would have from a simple neutralizing bath without
sulfite.
I still think acid stop baths prevent more problems than
they cause but certainly a plain water rinse works if it
actually washes out the bulk of the developer.
BTW, someone mentioned monobath processing. Much of the
research on this was done by Grant Haist. He wrote a small
book called _The Monobath Manual_ (very hard to obtain now)
and also covers monobaths in his _Modern Photographic
Processing_. Monobaths are not simply a mixture of developer
and fixer. They must be very carefully formulated and
matched to a specific emulsion. They have some very
interesting properties, not least of which is very
considerable immunity to temperature and time variations.
Haist shows some examples suggesting the possible image
quality is very high. For some reason monobaths have never
become popular except for some special rapid access uses.


--
---
Richard Knoppow
Los Angeles, CA, USA