When to use a hardener when processing B&W film

[xkaes]

Normally I either add a hardener to the fixer/hypo or leave it out completely. I've never thought much about other alternatives. Assuming you want to use a hardener (which is a completely different discussion) what would be the PROS and CONS of using these approaches:

#1: Treat the film with the hardener before the fixer
#2: Add the hardener to the fixer
#3: Treat the film with the hardener after the fixer but before a wash to remove the fixer
#4: Treat the film with the hardener after the fixer and after a wash to remove the fixer


What I can think of are:

#1 -- longer fixing times
#2 -- shorter fixing times
#3 -- even faster fixing time
#4 -- shorter washing time

[Doremus Scudder]

#1: Treat the film with the hardener before the fixer

Superfluous step when you can just go from the stop to a hardening fixer. Why invest time and more handling in an extra step.

#2: Add the hardener to the fixer

This has been the standard operating procedure for decades. Unless there is a reason to harden the emulsion before developing/stopping (e.g., high-temperature processing), this seems most practical and entails the fewest steps.

#3: Treat the film with the hardener after the fixer but before a wash to remove the fixer

Superfluous also, when you can just use a hardening fixer. Hardener does not affect the fixation significantly, so why not do both at the same time?

#4: Treat the film with the hardener after the fixer and after a wash to remove the fixer

I don't see the point of this. Usually hardener is there to protect the film when handling. After the wash all you have to do is dip it in wetting agent and hang it to dry; not much handling left.

What I can think of are:

#1 -- longer fixing times

I have never seen different fixing time recommended for hardening and non-hardening fixer. I don't think the hardener makes any significant difference. Adding 10% to the fixing time is inconsequential. I doubt if there is even that much of an increase.

#2 -- shorter fixing times
#3 -- even faster fixing time

See above.

#4 -- shorter washing time

Washing times can be shorter without hardener in the process. A treatment in a wash aid (e.g., Hypo Clearing Agent) will speed up the wash. The HT-2 test can give you information on the minimum wash times, and the ST-1 or the selenium-toner test can give you info on adequate fixation. I'm sure you're familiar with these. It shouldn't be hard to see if hardener affects fixing times or how much longer you need to wash with hardener in the process.

Of course, you shouldn't use hardener in your film developing sequence unless it is necessary, e.g., soft-emulsion films that are getting damaged during processing or high-temperature processing, etc.

Note that Kodak and others recommend using a hardener before development for high-temperature processing. Here's the salient paragraph from the Kodak Formulas booklet (1973):

"At higher temperatures, the use of KODAK Prehardener SH-5 before development will harden the emulsion sufficiently to allow use of normal solutions and processing procedures, even at temperatures as high as 43°C (110°F). Full instructions for use, including adjustment of developing time for various temperatures, are given with the prehardener formula in the "Formulas" section.
The use of the prehardener is the simplest and safest procedure for processing at high temperatures..." (the text continues to describe adding sodium sulfite to the developer in lieu of hardener.)

The formula for the prehardener is:

"KODAK Prehardener SH-5

Solution A
Formaldehyde, about 37% solution by weight ---- 5 ml
Solution B
Water -------------------------------------- 900 ml
*0.5% solution of KODAK Anti-Fog, No.2
(6-Nitrobenzimidazole Nitrate) ----------------- 40 ml
KODAK Sodium Sulfate (anhydr.) --------------- 50 g
KODAK Sodium Carbonate (monohydr.) --------- 12 g
Water to make -------------------------------- 1 liter

*To prepare a 0.5% solution, dissolve 1 gram of KODAK Anti-Fog, No. 2, in 200 ml of water.

Directions for mixing: The working solution should be prepared just before use by adding 5 ml of Solution A to 1 liter of Solution B and mixing thoroughly.

Directions for use: Bathe the exposed film in KODAK Prehardener SH-5 for 10 minutes with moderate agitation. Then remove the film from the solution, drain fro a few seconds, immerse in in water for 30 seconds, drain thoroughly, and immerse in the developer. In general, up to 32°C (90°F), conventional developers such as KODAK Developer D-76, DK-60a, D-19, etc, can be used without modification.
Times of development will be about as follows:

Temperature--- % of Normal Development Time*
24°C (75°F) ------ 100%
26.5°C (80°F) ----- 85%
29.5°C (85°F) ----- 70%
32°C (90°F) ------- 60%
35°C (95°F) ------- 50%

*Normal development time recommended when the developer is used at 20°C (68°F) without a prehardener.

Following development, rinse, fix in an acid hardening fixing bath [! NB], wash and dry in the usual way.

At Temperatures Above 35°C (95°F): Increase the concentration of KODAK Anti-Fog, No. 2, in the prehardener, using as much as double the normal formula concentration, if necessary, to control fog. Process as before, using a low-activity developer, such as KODAK Developer D-76, to avoid excessively short development times. The average development time at 443°C (110°F) after prehardening is about one quarter of the normal time at 20°C (68°F) .
In case the development time at elevated temperatures is too short for practical use, sodium sulfate can be added to the developer to extend the time of development.

Keeping Properties and Useful Capacity: The keeping properties are adequate for ordinary tray and tank practice. Gradual deterioration does occur on standing, but the bath will keep satisfactorily, if unused, in a closed bottle for 3 or 4 weeds at 35°C (95°F). For most applications, the useful capacity without replenishment is more than ten 8x10-inch (20.c x 25.4-centimeter) films per 946 milliliters (1 quart) without serious change in properties."

I don't know how readily available 6-Nitrobenzimidazole Nitrate is, or whether you could substitute BTA for it in the formula. Maybe some chemists here will add to the discussion.

Hope this helps,

Doremus

[Alan9940]

Doremus provides a through and complete reply, but if you decide to keep it simple by using a hardening fixer I've used the F-6 formula for years:

Water (at about 100F) 600ml
Sodium Thiosulfate (penta) 240g
Sodium Sulfite (anhy) 15g
Acetic Acid (28%) 48ml
Sodium Metaborate 15g (or Borax)
Potassium Alum 15g
Water to make 1L

Or, if you don't want to mix it yourself just buy some standard Kodak Fixer (powder) or Kodak Rapid Fix w/hardener. Don't know if Kodak chemistry is readily available, yet (given recent issues), but I believe it will return soon.

[Michael R]

Kodak Rapid Fixer + hardener has returned and should be available.

One caution regarding F-6 if the goal is hardening a non-hardened emulsion... it provides less hardening than F-5. The more acidic the environment, the more effective the alum hardener. The substitution of boric acid in F-5 with borate alkali to make F-6 raises the pH of the fixer, so you get significantly less hardening action.

Doremus provides a through and complete reply, but if you decide to keep it simple by using a hardening fixer I've used the F-6 formula for years:

Water (at about 100F) 600ml
Sodium Thiosulfate (penta) 240g
Sodium Sulfite (anhy) 15g
Acetic Acid (28%) 48ml
Sodium Metaborate 15g (or Borax)
Potassium Alum 15g
Water to make 1L

Or, if you don't want to mix it yourself just buy some standard Kodak Fixer (powder) or Kodak Rapid Fix w/hardener. Don't know if Kodak chemistry is readily available, yet (given recent issues), but I believe it will return soon.

[xkaes]

I've generally always used hardener in the fixer, but I've been using it less and less for various reasons, and since I mix my own, I began to wonder -- If I do use it, when is the best time? I was under the impression that hardening the emulsion increases the fixing time and the washing time.

[Tin Can]

Lol

[xkaes]

Superfluous also, when you can just use a hardening fixer. Hardener does not affect the fixation significantly, so why not do both at the same time?

I have never seen different fixing time recommended for hardening and non-hardening fixer. I don't think the hardener makes any significant difference. Adding 10% to the fixing time is inconsequential. I doubt if there is even that much of an increase.

Doremus

Here's what Stephen Anchell (second edition) says -- that adding hardener to the fix can double the fixing time.




That makes sense to me. So why not an extra step of hardening after fixing.

I'm thinking of doing the hardening after the washing to remove the fixer -- because the hardener also extended the wash to remove the fixer.

So shorter fixing times and shorter wash times if the film is hardened last -- or not hardened at all.

[Vaughan]

I'm thinking of doing the hardening after the washing to remove the fixer -- because the hardener also extended the wash to remove the fixer.

So shorter fixing times and shorter wash times if the film is hardened last -- or not hardened at all.

Usually the hardener is needed to ensure the gelatine will survive processing, which includes the wash which is often the longest wet step. Hardening after the wash is closing the door after the horse has bolted.

You'll need to consider the time needed to wash the hardener solution out.

[Michael R]

I’m not sure why one would use a hardener with most films unless processing (wash) temperatures are high and/or there is a high risk of mechanical damage during washing.

A hardening fixer generally requires both longer fixing and longer wash times. For an example see Ilford’s instructions for using Hypam with a hardener (the normal film processing rapid fixer time range is doubled). Ilford advises not to use a hardener with most films under normal circumstances and advises not to use a hardener with papers.

If one is determined to use a hardener follow the manufacturer’s directions (Kodak Rapid Fixer with Hardener, for example).

[Bill McMannis]

I am far from being an expert despite having processed a few thousand 35mm rolls and hundreds of 4x5’s over five decades. My one observation is if I skip hardener, my negatives dry flatter making for better enlargements or scans.