Hypo Clear - what does it do?

[removed account4]

that's a nice story and most likely an urban mythbut, is a possible explanation.I have more trust in photographic research.Sodium sulfite is a known solvent (see developers)and it's application for fixer removal is not a far-fetched idea.Agfa and Ilford tried othercompoundsbut,sodium sulfiteturned out to be most effective.So, probably not a lucky coincident at war but a scientific approachBut I agree, it makes the better story,

yeah probably...
science stories are nice but co-inky-dinky stories are more fun
" hey ensign we can't spare any more water to wash these negatives and prints, lets see what happens if we use ocean water"
" gee wilakers skipper there is no fixer left, i think you saved us a lot of water and we can market it after the war"
( skipper dies, ensign goes into the fixer removal business ...)

its almost like hollywood

 

[Kobin]

Is there any need for hypo clear when using ammonia based fixers?

K

 

[Rudeofus]

With respect to washing fiber based prints, again this is a complicated topic. The conventional wisdom is that washing is more efficient when an alkaline fixer is used, and that this therefore reduces or eliminates the utility of a hypo clearing step. We've had some lengthy discussion threads on this whole topic, but to date I haven't seen data/evidence.

I believe there is a section in Haist's "Modern Photographic Processing" about this. The move from Kodak F-5 to F-6 exemplifies that step: by adding Borate ion to their fixer, they were able to achieve hardening at slightly higher pH, which in turn allowed archival washing without HCA. Given that modern fixers neither need, nor have hardeners, and that Rapid Fixer operates at higher pH than Kodak F-6, we can safely assume that HCA is no longer needed. If one wants to be 100% sure, there are residual fixer testers to verify archival washing of film and prints.

 

[hoffy]

A typical home-mix formula contains sodium sulfite ~20g/l and some sodium bisulfite added to lower the pH.

Commercial formulas usually contain more compounds for stability, flexibility regarding water quality etc.:

Ilford Washaid contains sodium sulfite, sodium lauryl ether sulfate (surfactant/detergent), DTPA-free acid, and possibly other things.

Kodak HCA contains sodium sulfite, sodium metabisulfite, sodium citrate, EDTA, and possibly other things.

Do you need to add the sodium bisulfite? Define 'some' and 'lower the pH'.

 

[cliveh]

Is HCA really necessary, what's wrong with good old water (the universal solvent)?

 

[hoffy]

Using HCA will halve your washing time with Fibre prints.

 

[Mainecoonmaniac]

Thanks for the tip on washing

I use 10 minutes of HCA and then 20-30 minutes of washing, just to be on the safe side.

Due to the drought, 20-30 minutes can be a luxury that I might not be able afford. I might use a residual hypo test after 1- minutes of washing to see if it's adequate. This wash time is based on 10 minutes of HCA of course.

 

[polyglot]

30 minutes of running water is Right Out as far as people in Adelaide are concerned. However, 4 changes of water (in a tray) with 10+ minutes of soaking (including occasional agitation) in each bath does a very good job of washing FB. Less water than 30 minutes of trickle, but the important thing seems to be diffusion time.

It'd probably work even better if you put a little aquarium pump in to keep the thiosulfate ion concentration pretty uniform, i.e. get the thick stuff away from the paper surface.

 

[polyglot]

These are important points regarding washing. To repeat what I said earlier, washing is essentially a diffusion process. The thiosulfates (and/or other salts) migrate through the emulsion and paper fibers to the surfaces and accumulate in the water layers at the surfaces. A good washing system keeps removing this surface layer of water and replacing it with fresh water. If you think through this, you don't need a huge volume of water, just an efficient way of removing that surface layer and replacing it. Flowing water works fast, but if you have more time you can also use smaller amounts of water in a soak-dump type procedure.

PS if doing the soak/dump thing, consider the dump periods. As the level of thiosulfate reduces, the diffusion rate goes down so you want to space the earlier dumps quite close together and the latter ones further apart in order to get the best washing effect from a finite number of changes. A Jobo is a real handy thing but I suspect it probably only washes one surface of the paper properly; upside though is that once the paper is plastered into the drum, not much fixer will get to soak into the back of the paper.

What I do for FB is:
- develop, stop, 2-bath fix
- quick wash: 2 changes of water in 1 minute
- HCA for 2-3 minutes
- wash for 10 minutes in Jobo, changing water (about 200-800mL each time depending on paper/drum size) at 0:00, 0:15, 0:30, 1:00, 2:00, 4:00, 6:00, 8:00, 10:00
- take it out of the Jobo, transfer to tray / holding tank
- soak for ~45 minutes, changing water once per 10 minutes, agitating (bump/slosh the paper) every couple of minutes

I have a friend who has been doing FB B&W for about decades and he swears by just moving the print through a sequence of about 4 wash trays at (I think) half-hour intervals. Has prints from 30 years ago, they all seem fine.

 

[Gerald C Koch]

A good washing system keeps removing this surface layer of water and replacing it with fresh water. If you think through this, you don't need a huge volume of water, just an efficient way of removing that surface layer and replacing it.

Precisely, a laminar flow. I have used this method for decades for roll film. I use a plastic cylinder with a number of tiny holes at the bottom. The cylinder holds 4 reels. Water enters the top at a very low rate and exits from the bottom. Water input is adjusted so that the cylinder always remains full. The total amount of water used is small compared to other methods. The secret is in the size of the holes. You want a very slow flow rate to avoid any turbulence. A similar system can be used for prints.

 

[hoffy]

PS if doing the soak/dump thing, consider the dump periods. As the level of thiosulfate reduces, the diffusion rate goes down so you want to space the earlier dumps quite close together and the latter ones further apart in order to get the best washing effect from a finite number of changes. A Jobo is a real handy thing but I suspect it probably only washes one surface of the paper properly; upside though is that once the paper is plastered into the drum, not much fixer will get to soak into the back of the paper.

What I do for FB is:
- develop, stop, 2-bath fix
- quick wash: 2 changes of water in 1 minute
- HCA for 2-3 minutes
- wash for 10 minutes in Jobo, changing water (about 200-800mL each time depending on paper/drum size) at 0:00, 0:15, 0:30, 1:00, 2:00, 4:00, 6:00, 8:00, 10:00
- take it out of the Jobo, transfer to tray / holding tank
- soak for ~45 minutes, changing water once per 10 minutes, agitating (bump/slosh the paper) every couple of minutes

I have a friend who has been doing FB B&W for about decades and he swears by just moving the print through a sequence of about 4 wash trays at (I think) half-hour intervals. Has prints from 30 years ago, they all seem fine.

I'd be curious to know how much water you are actually using - I am using more water then you, but possibly not much more:
- develop, stop, 2-bath fix
- quick wash: 5 mins with flowing water, dumping the water every minute
- HCA for 10 minutes, agitating every few minutes.
- very quick surface rinse
- paterson print washer for 30 mins to 1 hr (a lot depends on what I am actually doing at the time...)

According to the Ilford literature, these wash times are probably on the excessive side, but based on the info I have read here and in Ralphs book, I have erred on the side of caution

The thing is that I have never tested for residual fix - next time I order from Freestyle, I will add a test kit to the order..

Michael, thanks for the tip. I am going to try and track down some sodium sulfite and just mix that each session I print. Surely it has to be cheaper then dumping working HCA after each session.

Edit - tracked some down locally 500g for $37 or 5kg for $71....anyone in Adelaide what to split some?

 

[walbergb]

I'm no expert, but I do test my prints periodically for residual silver and residual hypo. As I have come to understand it the 3-5 minute HCA bath is with constant agitation, much like using HCA with film. The 10 minute method requires only occasional agitation.

I use the Ilford protocol for fibre prints: 5 minute wash after fixing (2-bath method), 10 minute HCA bath, 5 minute wash. I believe these times are based on the use of a vertical washer, which I use. My tests for residual hypo tell me that with my procedure, materials, and equipment a 5 minute final wash is a minimum and not always sufficient. Therefore, my final wash is 10 minutes minimum. I time every step of the process, so I am consistent. Using dedicated timers for the final 3 steps allows me to multi-task.

I, too, use straight sodium sulfite for paper. I buy it from Photographers' Formulary in Montana (and an APUG supporter).

 

[polyglot]

I have cheap HCA from freestyle; I single-shot it about 150-400mL (depending on tank size, working solution) at a time. I'd consider buying a kilo or two of sulfite though and I'm sure a few more AFDUGers would help out. Where was this from, a brewers supply or something?

My guess is your washer would have to be using at least 1L/minute though, which I suspect is a lot more than the 15-20L that I use per session.

Gerald: a matter of terminology perhaps, but a laminar (layered) flow is NOT desirable as it implies the existence of a stationary layer at the surface, with fluid velocity increasing as you get further away. What you need for washing is "plug flow", which is a form of turbulent flow that produces good motion right down to the surface. Getting that uniformly across a surface is difficult though.

 

[Rudeofus]

For self mixers: if you mix 20 g/l Sodium Sulfite into regular tap water (at least here in Central Europe), you get a very murky solution, presumably from water hardness. There are some methods for preventing this, and no, you do not want to wash your prints in a murky liquid:

• Lower pH with Sodium Metabisulfite as suggested earlier in this thread. I have noticed that pH ends up below neutral before the liquid clears, so this may not lead to a working HCA. AFAIK all HCA formulas are alkaline.
• Add a sequestering agent: I've had good luck with Dequest 2010, but Calgon, Na2-EDTA, Na4-EDTA, DTPA should all work. Put in the sequestering agents first, then add the Sodium Sulfite (CaSO3 is very insoluble).
• Citric Acid lowers pH, but also acts as weak sequestering agent for water hardness. Use with care, as pH will readily drop below neutral. The good thing about Citric Acid is that you get it in food stores, so it's easily available. If you use this, first completely dissolve the Sulfite, then add and dissolve just enough Citric Acid to make the murkiness clear up.

 

[Dr Croubie]

I'm nearly out of my current packet of Kodak Hypoclear, I was thinking about Ilford Washaid next time (just because I like liquids).
If anyone's splitting Sodium Sulphite, count me in for some too. Can it also be used on films too (esp TMax/Delta), or just Paper?

 

[pdeeh]

Dequest 2010, but Calgon, Na2-EDTA, Na4-EDTA, DTPA should all work.

My tap water is of a kind that a a precipitate is thrown when I mix sulfite (or carbonate) without first adding a gram or two of Sodium hexametaphosphate per litre

I can never find anywhere to buy Dequest, at least in "consumer" quantities. Where do you get yours?

Calgon - the Calgon that I find in the supermarket here no longer contains Sodium hexametaphosphate (which is what photographers habitually refer to "Calgon"); but hexametaphosphate is still quite easy to find online from suppliers of dyers' sundries.

 

[Rudeofus]

My tap water is of a kind that a a precipitate is thrown when I mix sulfite (or carbonate) without first adding a gram or two of Sodium hexametaphosphate per litre

I can never find anywhere to buy Dequest, at least in "consumer" quantities. Where do you get yours?

I got mine from a lab nearby, but you can order it from Suvatlar, it's sold there under the name "Fotoplex2 (Hydroxyethyliden-diphosphonsäure)".

Calgon - the Calgon that I find in the supermarket here no longer contains Sodium hexametaphosphate (which is what photographers habitually refer to "Calgon"); but hexametaphosphate is still quite easy to find online from suppliers of dyers' sundries.

What does it contain instead? If it grabs the Ca2+ and doesn't interfere with photochemistry it may still work ...

 

[baachitraka]

Lucky that water in Bremen is not so bad. Solution stays clear...

For self mixers: if you mix 20 g/l Sodium Sulfite into regular tap water (at least here in Central Europe), you get a very murky solution, presumably from water hardness. There are some methods for preventing this, and no, you do not want to wash your prints in a murky liquid:

• Lower pH with Sodium Metabisulfite as suggested earlier in this thread. I have noticed that pH ends up below neutral before the liquid clears, so this may not lead to a working HCA. AFAIK all HCA formulas are alkaline.
• Add a sequestering agent: I've had good luck with Dequest 2010, but Calgon, Na2-EDTA, Na4-EDTA, DTPA should all work. Put in the sequestering agents first, then add the Sodium Sulfite (CaSO3 is very insoluble).
• Citric Acid lowers pH, but also acts as weak sequestering agent for water hardness. Use with care, as pH will readily drop below neutral. The good thing about Citric Acid is that you get it in food stores, so it's easily available. If you use this, first completely dissolve the Sulfite, then add and dissolve just enough Citric Acid to make the murkiness clear up.

 

[hoffy]

I have cheap HCA from freestyle; I single-shot it about 150-400mL (depending on tank size, working solution) at a time. I'd consider buying a kilo or two of sulfite though and I'm sure a few more AFDUGers would help out. Where was this from, a brewers supply or something?

My guess is your washer would have to be using at least 1L/minute though, which I suspect is a lot more than the 15-20L that I use per session.

Gerald: a matter of terminology perhaps, but a laminar (layered) flow is NOT desirable as it implies the existence of a stationary layer at the surface, with fluid velocity increasing as you get further away. What you need for washing is "plug flow", which is a form of turbulent flow that produces good motion right down to the surface. Getting that uniformly across a surface is difficult though.

The sulfite was from Ace Chemicals (no - they have nothing to do with the Joker....). When I spoke to them on the phone, it sounded like that they knew exactly what I was planning for it - they even called it "photo grade".

As for washing, the other difference with using a print washer is number of prints washed at once - last time I used it, there were 8 being washed at the same time.

 

[pdeeh]

What does it contain instead? If it grabs the Ca2+ and doesn't interfere with photochemistry it may still work ...

The FAQ on the Calgon UK (brand owned by Reckitt Benckiser) website says "active ingredients being polycarboxylates which softens hard water, preventing limescale from forming"

 

[Rudeofus]

The FAQ on the Calgon UK (brand owned by Reckitt Benckiser) website says "active ingredients being polycarboxylates which softens hard water, preventing limescale from forming"

Polycarboxylates are good, there are a number of polycarboxylates in the list I gave before: EDTA, DTPA. I would be very surprised if this version of Calgon wouldn't work for HCA.

 

[Gerald C Koch]

There are a number of condensed phosphates that can be used for water softening. Calgon (trade name) is only one of them. They all are slowly hydrolysed in water solution back to ordinary phosphates with the loss of their water softening ability. Another reason against saving HCA for extended periods for reuse.

 

[Rudeofus]

Since there was a major push across the western world against phosphates, I would assume that many commercial formulations have silently switched to Na2-EDTA in the mean time. If even "Calgon" sold today uses polycarboxylate, presumably Na2-EDTA ...