Clearing Agent in BNW processing

I have a procedure for developing 35mm negatives that requires, after
fixation, to use a 'hypoclearing agent' (using kodak d-79 developer and
fixer). Is this necessary?

I had thought that I can use a 28% dilution of acetic acid for this, or
is that good for something else??

the agent

http://www.kodak.com/global/en/profe...4.7.46&lc =en

Also, what is the difference between stock solution and working
solution, for say developer? When I make it per the mixing
instructions, resulting in a gallon, do I have the stock solution or
the working solution? What do I have to do to get it to the working
solution then? Or does 'working solution' simply mean 'the volume that
you are working with right now'?

Because I am looking here

http://www.kodak.com/global/en/profe...4.14&lc=en#004

and it says a working solution lasts one month in a tank/bottle. I'm
wondering if its at all worth it to make a 'stock' solution and store
that for a while. Probably not tho.

wrote:
I have a procedure for developing 35mm negatives that requires, after
fixation, to use a 'hypoclearing agent' (using kodak d-79 developer and
fixer). Is this necessary?

Hypo Clearing Agent is mostly Sodium Sulphite. Its purpose is
to speed up washing times for films and fibre based paper.
Its use is not strictly necessary if you are prepared to use
long washing times instead.

Washing a film fixed in a hardening fixer usually takes 20-30 minutes.
With HCA you can reduce this time to around 10 minutes. If you use
a non-hardening fixer, washing times may be as little as 10-15 minutes
even without HCA. I use it because it is a good way to make sure your
film is properly washed.

I use HCA one shot. I dilute the stock solution shortly before
use and then pour it down the drain after the film has been in
it for a few minutes. If I am using fibre based paper, I will have
one tray of HCA for the whole session. (Fibre paper takes an hour
to wash without HCA, but only half that long with HCA).

I had thought that I can use a 28% dilution of acetic acid for this, or
is that good for something else??

Acetic acid is often used for a stop bath between the developer
and the fixer. It is normally diluted to somewhere around 1 1/2%
strength. Stop bath is not strictly necessary either, some people
use a couple quick changes of water instead.

The order of processing is:
developer - stop-bath - fixer - HCA - wash - photoflo - dry

Also, what is the difference between stock solution and working
solution, for say developer? When I make it per the mixing
instructions, resulting in a gallon, do I have the stock solution or
the working solution?

The instructions on the package are for making the stock solution.
The stock solution of D-76 developer has a life of at least six
months in full, tightly closed glass bottles. If you are making
a gallon, it is usually best to store developer in several smaller
bottles so that the bottles remain full until you start to use them,
a partly filled bottle has a much shorter shelf-life than a full one.

You can use D-76 straight or diluted with an equal volume of water
(This is called D-76 1:1) Most people nowadays use the 1:1 working
solution because it gives slightly longer development times and
is economical to use on a one shot basis. If you use the 1:1 dilution
you should use it once only. If you use the straight stock solution,
you can reuse it a few times, but it will fall off slightly in
activity each time you use it. People who use a lot of developer
often add replenisher to the developer after each use: this is very
economical if you use a lot of developer. For most of us, using the
1:1 solution one shot is the best way to go. There are complete
instructions in the D-76 datasheet pdf.

What do I have to do to get it to the working
solution then? Or does 'working solution' simply mean 'the volume that
you are working with right now'?

- Stock solution = developer as mixed and not yet used
- working solution = developer in use, possibly diluted

Because I am looking here

http://www.kodak.com/global/en/profe...4.14&lc=en#004

and it says a working solution lasts one month in a tank/bottle. I'm
wondering if its at all worth it to make a 'stock' solution and store
that for a while. Probably not tho.

The "working solution in tank with floating lid" applies to people
with large tanks who keep the same developer in their tanks for
up to a month. This does not apply to most of us.

What I suggest is that you fill several small bottles with fresh
D-76, and dilute this "stock solution" with an equal volume of
water just before use. After you have developed the film, pour
the used developer down the drain and flush it with plenty of
water. The full bottles of D-76 will keep for at least six
months, probably much longer. Partly used bottles can only be
trusted for two months. It is a good idea to have a label on
each bottle which states what it is, when you made it up, and
when you started using that bottle.

I hope I have been clear. If not, you can try asking at
rec.photo.darkroom.

Peter.
--

wrote in message
ups.com...
I have a procedure for developing 35mm negatives that requires, after
fixation, to use a 'hypoclearing agent' (using kodak d-79 developer and
fixer). Is this necessary?

I had thought that I can use a 28% dilution of acetic acid for this, or
is that good for something else??

the agent

http://www.kodak.com/global/en/profe...4.7.46&lc =en

Hypoclearing just reduces wash time (by about 75%). You'll have to wash
your film for 20-30 minutes as opposed to 5-10 minutes. And no, the acetic
acid could be used as a stop after developing, but won't hypoclear a thing.
These questions are best posted rec.photo.darkroom--you'd have ten answers
already, including suggestions for making your own hypoclear! (maybe)


Also, what is the difference between stock solution and working
solution, for say developer? When I make it per the mixing
instructions, resulting in a gallon, do I have the stock solution or
the working solution? What do I have to do to get it to the working
solution then? Or does 'working solution' simply mean 'the volume that
you are working with right now'?

With hypo clear you mix a stock and from that you dilute 1:4

Because I am looking here

http://www.kodak.com/global/en/profe...4.14&lc=en#004

and it says a working solution lasts one month in a tank/bottle. I'm
wondering if its at all worth it to make a 'stock' solution and store
that for a while. Probably not tho.


That's what I do. I never make a working solution, except in the canister
thingy itself. I just take the top off and eyeball 1:4--the film's already
fixed then so there's no worries.

--
Regards,
Matt Clara
www.mattclara.com

In article . com,
wrote:

I have a procedure for developing 35mm negatives that requires, after
fixation, to use a 'hypoclearing agent' (using kodak d-79 developer and
fixer). Is this necessary?

It is if you're using TMAX film (it's what clears the purple coloring
from the film).


I had thought that I can use a 28% dilution of acetic acid for this, or
is that good for something else??

No, use proper hypo-clear.

Chris

In article . com,
wrote:

I have a procedure for developing 35mm negatives that requires, after
fixation, to use a 'hypoclearing agent' (using kodak d-79 developer and
fixer). Is this necessary?

It is if you're using TMAX film (it's what clears the purple coloring
from the film).


I had thought that I can use a 28% dilution of acetic acid for this, or
is that good for something else??

No, use proper hypo-clear.

Chris

wrote:

I have a procedure for developing 35mm negatives that requires, after
fixation, to use a 'hypoclearing agent' (using kodak d-79 developer and
fixer). Is this necessary?

I had thought that I can use a 28% dilution of acetic acid for this, or
is that good for something else??

28% acetic acid - or 'glacial' acetic acid is too strong as is for a
stop bath. The usual dilution is 48ml of 28% acetic acid to a litre of
water, to make a final solution of about 1.4 - 1.7% acetic acid. The
action of the stop bath is to arrest the developer activity, as most
developer solutions work in an alkaline environment, and an acid
environment stops the developer action immediately.

Colin

wrote:

I have a procedure for developing 35mm negatives that requires, after
fixation, to use a 'hypoclearing agent' (using kodak d-79 developer and
fixer). Is this necessary?

I had thought that I can use a 28% dilution of acetic acid for this, or
is that good for something else??

28% acetic acid - or 'glacial' acetic acid is too strong as is for a
stop bath. The usual dilution is 48ml of 28% acetic acid to a litre of
water, to make a final solution of about 1.4 - 1.7% acetic acid. The
action of the stop bath is to arrest the developer activity, as most
developer solutions work in an alkaline environment, and an acid
environment stops the developer action immediately.

Colin

Colin D wrote:

wrote:

I have a procedure for developing 35mm negatives that requires, after
fixation, to use a 'hypoclearing agent' (using kodak d-79 developer and
fixer). Is this necessary?

I had thought that I can use a 28% dilution of acetic acid for this, or
is that good for something else??


28% acetic acid - or 'glacial' acetic acid is too strong as is for a
stop bath. The usual dilution is 48ml of 28% acetic acid to a litre of
water, to make a final solution of about 1.4 - 1.7% acetic acid. The
action of the stop bath is to arrest the developer activity, as most
developer solutions work in an alkaline environment, and an acid
environment stops the developer action immediately.

Colin


I'm not the guy who asked the question, but thanks Colin for a useful
answer to the question.

Regards,

DAve

Colin D wrote:

wrote:

I have a procedure for developing 35mm negatives that requires, after
fixation, to use a 'hypoclearing agent' (using kodak d-79 developer and
fixer). Is this necessary?

I had thought that I can use a 28% dilution of acetic acid for this, or
is that good for something else??


28% acetic acid - or 'glacial' acetic acid is too strong as is for a
stop bath. The usual dilution is 48ml of 28% acetic acid to a litre of
water, to make a final solution of about 1.4 - 1.7% acetic acid. The
action of the stop bath is to arrest the developer activity, as most
developer solutions work in an alkaline environment, and an acid
environment stops the developer action immediately.

Colin


I'm not the guy who asked the question, but thanks Colin for a useful
answer to the question.

Regards,

DAve

Colin D wrote:



28% acetic acid is too strong as is for a
stop bath. The usual dilution is 48ml of 28% acetic acid to a litre of
water, to make a final solution of about 1.4 - 1.7% acetic acid. The
action of the stop bath is to arrest the developer activity, as most
developer solutions work in an alkaline environment, and an acid
environment stops the developer action immediately.

Colin

I'm not the guy who asked the question, but thanks Colin for a useful
answer to the question.

Regards,

DAve

Ok Dave, pleased to drop a diamond, as my old mother used to say. Note
that 28% acid is not glacial, I could have put that better, though.
Glacial acid is about 98% pure, freezes at about 16.7 deg C, so in a
cold room it will freeze, hence the term 'glacial'. The fumes from
glacial acetic acid are quite corrosive and will do your lungs a lot of
no good. This is why most supplies are 28% strength, but at that it
still has a pungent smell which will trigger asthmatics into a bout of
wheezing, so don't breathe it any more than necessary.

Colin