How important is HCA?

rob91 · Sep 15, 2008

The process that I learned in school, and what I've been using since, is after the fixer 2 min water rinse, 2 min HCA, then a 5 minute water rinse. Is HCA necessary? If not, how would I alter my plan? Thanks.

compur · Sep 15, 2008

My "bibles" for film developing are Steve Anchell's books, The Darkroom
Cookbook and The Film Developing Cookbook.

Most fixers are acidic but Steve recommends using an alkaline fixer and he
states that when using an alkaline fixer no HCA is needed and film wash times
are also greatly reduced. Photographer's Formulary sells an alkaline fixer
called TF-4, also available from Freestyle. This is what I use. An alkaline fixer
is also far less likely to cause pinholes then acid fixers.

Steve also gives a simple formula for mixing your own alkaline fixer from
scratch in his books.

If using an acid fixer, though, you do need to use HCA for archival permanence.

ann · Sep 15, 2008

are you talking about with film or papers?

for film and RC papers there is no need for HCA

for fiber papers it is very helpful for reducing the wash times

rob91 · Sep 16, 2008

I'm talking about film. I use Kodak rapid fixer, btw.

JC1220 · Sep 16, 2008

The risk of pinholes comes with the use of acid stop baths that are not buffered well and with a pH higher than say 4. When the sodium carbonate, in most developers, hits the acid stop carbon dioxide gas is created in the emulsion causing the pinholes.

Acid fixers are typically lower acid pH around 5.5 and are typically not the cause of pinholes. I suppose it is possible if you plunge the film right out of the developer into the fix it may happen, but the fix will most likely become quickly exhuasted without doing a water rinse prior.

Also, if you skip the stop bath and go with a water "stop" know it does not actually stop development, so you will need to adjust your development time to account for this.

compur · Sep 16, 2008

^ Yes, that's true. I forgot to mention I also use a water stop bath as Anchell recommends, making it it all all non-acid process.

rob91 · Sep 17, 2008

compur, do I need a non-alkaline fixer, or were you referring to something else?

compur · Sep 17, 2008

I use a water bath stop and an alkaline fixer called TF-4.

That makes the whole process non-acidic since developers are
also alkaline and water is, of course, neutral.

It's my belief that this is a very archival way to process and is
also simpler & faster because no HCA is necessary and wash
times are reduced when processing this way. There is also
less chance of "PH shocking" emulsions by going from an alkaline
developer to an acid stop and fix which can cause reticulation,
pinholes, etc.

However, regular acid fixers are much more plentiful and may
be cheaper too. Most photographers use them and I don't
mean to say they are doing anything wrong. I just like to
treat my materials as gently as possible. But, there's nothing
wrong with using an acid fixer -- just use HCA and wash
thoroughly when you do if you want your negs and prints to
last a long time.

The preceding is purely my opinion and the way I like to do
things.

rob91 · Sep 17, 2008

How do I tell if my fixer is alkaline or acidic? This is what I use: http://www.freestylephoto.biz/sc_prod.php?cat_id=&pid=504

btw comp, whats your average fixing time for that fixer?

Helen B · Sep 17, 2008

There are also neutral fixers, often intended for use with C-41*.

If you are using a rapid fixer and it has not been overused, you should be OK without HCA for film. You might want to consider switching to a set of water changes (say six, to be on the safe side) with constant agitation for one minute instead of your current wash method.

Washing fixer out of film is easy. Washing intermediate silver complexes out of the emulsion after incomplete fixing is more of a problem, therefore it is important not to overuse fixer. One way of ensuring complete fixing while staying economical is to use a two-bath fixing process.Most of the fixing is done in the first bath, and the second does very little.

The first bath may be discarded when the clearing time is double that of fresh fixer. What was the second bath then becomes the first bath, and a fresh second bath is made up.

As an aside, The Film Developing Cookbook is attributed to Steve Anchell and Bill Troop. Many of the formulae are Bill Troop's. A formula beginning TD or TF is likely to be a Bill Troop formula (TD for Troop developer and TF for Troop fixer, such as TF-4).

Best,
Helen

*Edit: An example is Kodak Flexicolor Fixer, a rapid fixer which has a pH of 6.5 at working strength - ie close to neutral. It is often easier to find such fixers than it is to find TF-4 if you don't want to pay for shipping liquids.

Helen B · Sep 17, 2008

rob91 said:
How do I tell if my fixer is alkaline or acidic? This is what I use: http://www.freestylephoto.biz/sc_prod.php?cat_id=&pid=504

That's a regular sodium thiosulphate fixer, with ammonium alum hardener. It has a pH of around 4.5 at working strength - ie it is an acid fixer.

When I use TF-4 my fixing time is usually one minute in each fixing bath.

Best,
Helen

rob91 · Sep 17, 2008

Thanks Helen.

When you say "each fixing bath" are you referring to the two bath process you describe, or two separate fixers?

Also, something interested I noticed while researching: http://www.usefilm.com/Photo_Forum/13/1012562/

You're everywhere!

Helen B · Sep 17, 2008

Yes, sorry. I meant each bath of a two-bath fixer.

That Usefilm post was rather brief, and a little oversimplified. You'll notice that ann contributed to that thread as well.

Best,
Helen

Edit: photo.net is always 'lively and interesting'... (link 1, link 2)

compur · Sep 17, 2008

rob91 said:
How do I tell if my fixer is alkaline or acidic? This is what I use: http://www.freestylephoto.biz/sc_prod.php?cat_id=&pid=504

All the Kodak fixers for B&W are acid. The only commercially available
alkaline fixer for B&W materials that I am aware of is TF-4 from
Photographers Formulary and available from Freestyle. (There is also
at least one neutral fixer for B&W but I've never used it).

You can also mix your own alkaline fixer from scratch if you decide
you want to get into mixing your own chemistry. I find it very
enjoyable myself but not everybody does.