Pyro

[Pawlowski6132]

Will folks here typically use a HCA after fixing?

How 'bout Photoflo type post rinse?

Will either of these affect the stain?

thanx in adavnce

Joe

[Drew Wiley]

Hypo clearing agent is not recommended with pyro. Better to use an alkaline archival
fixer such as TF4 or TF5, which is easier to use anyway. Photoflo is always necessary
in distilled water as a final rinse, after the general rinse, to avoid spotting from minerals
in tap water.

[Pawlowski6132]

Hypo clearing agent is not recommended with pyro. Better to use an alkaline archival
fixer such as TF4 or TF5, which is easier to use anyway. Photoflo is always necessary
in distilled water as a final rinse, after the general rinse, to avoid spotting from minerals
in tap water.

Thanx Drew. Just got some TF4 so...I'm in business.

Sounds like you're an experienced pyro developer so...lemme ask you another question: Can I use the same filter combinations on my Omega color head to control contrast or, will the color of the stain on the negative impact this?

thanx again

[Ken Lee]

"Hypo clearing agent is not recommended with pyro"

I've never heard that before. Where did you learn that please ?

The active ingredient in Hypo Clearing Agent or Washing Aid, is Sodium Sulfite.

I always use a dilute solution after TF-3 Alkaline Fixer (and TF-4 before I started mixing my own chemistry).

I use it with Pryocat HD and all other developers, whenever developing b&w film. Sodium Sulfite not only removes the fixer, it also helps remove the magenta anti-halation layer found in Kodak TMY and TMX films.

Sodium Sulfite has many purposes in photographic chemistry: it also makes a great cleaner for removing the stain in wine bottles, for re-use as vacuum storage bottles.

[Gem Singer]

Ken,

See: S. Anchell and B. Troop, "The Film Developing Cookbook".

"A hypo clearing agent is not necessary when using an alkaline fixer".

A similar statement is included in the instruction sheet with TF-4 and TF-5 fixers from The Photographer's Formulary.

My guess is that alkaline sodium sulfite neutralizes acid fixers. No acid in the fixer, no need to neutralize.

As you know, acid fixers are not recommended with pyro developers. However, HCA does not affect the staining effect of a pyro developer.

As for the magenta color of the anti-halation layer of TMX and TMY films, HCA does help with the removal of that stain, but so does adequate washing and air drying.

Sulfite is often used as an anti-oxidant in wine and many food products.

[Andrew O'Neill]

Rubbish. I've been using HCA both store bought and homemade without ill effects on the stain for years.

[CP Goerz]

I read in that big fat book on print/film longevity that HCA wasn't recommended for film. The reason they gave was that a chemical reaction can take place and could create gas bubbles which in a print is OK as the bubbles can slip out through the fiber of the paper but in film its either punching a hole in the backing or a nice pop through the emulsion.


If Andrew hasn't noticed this anytime then perhaps its a bit overplayed and probably best ignored. I never used it on HCA except on paper prints so can't really say...I just wanted to SCARE you! :-)

[nolindan]

Stain formation is, it seems, a two-step process.

Pyro is a reducing agent -- an anti-oxidant, so you know it's good for you! [insert sarcastic smiley] When it is oxidized in the process of developing silver grains it turns dark brown, like most developing agents - first step. The oxidized pyro then polymerizes with the gelatin forming poly-phenol chains - second step, essentially tanning the gelatin. It takes a while for the second step to complete and it is usually still proceeding in the fix and wash. Sulfite interferes with the formation of polyphenol chains in step 2, though once polymerization has completed all the sulfite in the world won't budge the stain.

So the answer seems to be both yes and no. Sulfite does interfere with stain formation but after the stain has fully formed sulfite has no effect. If the stop/fix/rinse time is long enough then HCA will have no effect on the stain.

Pyro and catechol are some of many compounds formed by plants to repel insect invaders. Catechol is found in apples, bananas and potatoes, gallol is found in oak trees. These compounds remain dormant in the plant until they are exposed to oxygen when the plant or fruit is opened. When the insect eats the oxidized catechol/gallol compounds they form polyphenol polymers with the proteins in insect's digestive tissue - turning the critter's guts into tanned leather. The compounds also have some antimicrobial properties.

Most tanning agents, present in many leaves, barks and fruits, will develop film.

[Kirk Keyes]

I read in that big fat book on print/film longevity that HCA wasn't recommended for film. The reason they gave was that a chemical reaction can take place and could create gas bubbles which in a print is OK as the bubbles can slip out through the fiber of the paper but in film its either punching a hole in the backing or a nice pop through the emulsion.

You're confusing Hypo Eliminator with Hypo Clearing Agent.

Hypo Eliminator is a mix of hydrogen peroxide and ammonia - it generates oxygen as it converts thiosulate in to sulfate.

Hypo Clearing Agent does not generate oxygen and no gas bubbles.

HCA is certainly acceptable and recommended for films to speed up washing.

[bob carnie]

The colour of the stain will impact the starting filtration.

for normal 4x5 negs developed in D76 or non pyro dev, my starting filtration would on a dichroic enlarger would be around 10m-20magenta , wheras a pyro stained neg, (I use the Hutchings formula) I would start at around 30-50 magenta depending on the lighting conditions of the original scene.
I use a modified split filter method and would follow the above with a 200 magenta hit to bring in contrast.

If you are not split printing then your starting numbers may need to be higher.