Hypo Clear - what does it do?

[Marco Buonocore]

I use hypo clear all the time - particularly when processing fibre prints.

My question is: what does it do?

How does something as simple as 20g of sodium sulfite per litre of water save me so much washing time?

Thanks!

 

[Marco Buonocore]

Fantastic answer! Thank you, Michael!

This leads me to a second question: if hypo clear is used to deal with an excess of thiosulfate, is there any point in using it after sepia toning?

 

[removed account4]

what michael said ...

think of it this way ...
you fixed the paper ( or film )
and after you rinsed the print ( or negative ) off
you still have fixer kind of loitering and no matter how much they are told to take off they don't ...
the perma wash, hypo clear, fixer remover ... whatever you want to use
is absorbed into the print / negative and displaces/grabs the fixer and drops it out of the print/negative
so in the end you aren't washing out as much fixer, but the fixer remover which doesn't mind
getting washed off/ getting kicked your print/negative for loitering ... so your wash times are shortened ...

from what i have read ...
they learned about this stuff during the 2nd world war when the us navy ( and maybe others? ) started to wash film and paper in sea water
( which contains a lot of sulfites ) and shortened wash times so save on fresh water. so after ww2 photochemistry companies
figured out what it was in the sea water that did this and sold it as a product ...

 

[Mainecoonmaniac]

Never knew how HCA worked

The chemistry is complex but essentially what is happening is an ion exchange. The adsorbed thiosulfate ions remaining from the fixing process are displaced by sulfite ions. This makes the washing process (essentially a diffusion process) more efficient as adsorbed thiosulfates are relatively slow and difficult to diffuse out of the emulsion/paper.

So sulfite ions are easier to wash out?

Very informative.

 

[polyglot]

So sulfite ions are easier to wash out?

Very informative.

They don't have the same negative impact on the silver print if left behind either.

 

[NedL]

Is there any easy test to know if your sodium sulfite solution is used up? I've got a liter that I'm wondering if I should replace...

 

[removed account4]

hi ned

i use perma wash and there is a capacity printed on the bottle.
they say 1 gallon is good for x many prints, i usually mix 1 quart
and divide by 4 ... and usually just use it single shot, its not expensive ...
so i don't bother with capacities ... not sure what other maker's say ...

 

[NedL]

That's what I get for mixing it from scratch... no capacity on the label!
But you're right it's not expensive, I should just make fresh.

 

[Gerald C Koch]

The problem with reusing a washing aid like HCA is that the alkaline medium combined with bits of emulsion provide a great breeding ground for various kinds of bacteria. This is what causes the slime that forms in a reused bath that many people observe. There are ways to prevent this like the addition of Liserine but the easiest (and best) is just to discard the bath after use.

 

[hoffy]

Quick question - is it necessary to agitate when in the Hypo Clear? Or is it best to let it sit and do what it does?

 

[MattKing]

Kodak recommends agitating continuously for at least the first 30 seconds, and then every 30 seconds thereafter.

 

[NedL]

The problem with reusing a washing aid like HCA is that the alkaline medium combined with bits of emulsion provide a great breeding ground for various kinds of bacteria. This is what causes the slime that forms in a reused bath that many people observe. There are ways to prevent this like the addition of Liserine but the easiest (and best) is just to discard the bath after use.

Thanks!

Mine still is clear as water. Oddly enough that's what got me wondering how I'll know when it's reached capacity! But what you wrote makes good sense.

 

[Rudeofus]

Does a bath containing significant amounts of Sulfite really allow germ growth, or is germ growth an indication that all Sulfite has been converted to Sulfate and the bath should be replaced ASAP?

 

[Wade D]

I have some boxes of Kodak HCA that I got from a photography studio that closed in the 70's. Each box makes 5 gal. but all of them are as hard as bricks. The powder is still white when crushed up and residual hypo checks are good after use. Any thoughts as to using it or not?

 

[Terry Christian]

I think they should still be fine, Wade. The hardness would be due, as with all dry chemicals, to the absorption of moisture from the air. They should still be perfectly viable. I don't think atmospheric conditions deteriorate sulfite.

 

[RalphLambrecht]

what michael said ...

think of it this way ...
you fixed the paper ( or film )
and after you rinsed the print ( or negative ) off
you still have fixer kind of loitering and no matter how much they are told to take off they don't ...
the perma wash, hypo clear, fixer remover ... whatever you want to use
is absorbed into the print / negative and displaces/grabs the fixer and drops it out of the print/negative
so in the end you aren't washing out as much fixer, but the fixer remover which doesn't mind
getting washed off/ getting kicked your print/negative for loitering ... so your wash times are shortened ...

from what i have read ...
they learned about this stuff during the 2nd world war when the us navy ( and maybe others? ) started to wash film and paper in sea water
( which contains a lot of sulfites ) and shortened wash times so save on fresh water. so after ww2 photochemistry companies
figured out what it was in the sea water that did this and sold it as a product ...

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,

 

[Mainecoonmaniac]

I have a couple of questions about using HCA. Normally, I wash my prints out of the 2nd fix for about 10 minutes than soak my prints in HCA for about 15 minutes than wash 30-45 minutes. I'm going to have to change my washing work flow due the the California drought. Does soaking overnight reduce wash time? Also, I've read an article from David Vestal that it's safe to wash prints back to back in an archival print washer. I'm actually thinking about washing my prints outside so I can water my landscaping.

 

[baachitraka]

I do what ILFord recommends for film for washing the prints but after soaking in Sodium Sulphite for 10-20 mins.

After exchanging water for four to five time I let it soak overnight in bath tub.

 

[Gerald C Koch]

Does a bath containing significant amounts of Sulfite really allow germ growth, or is germ growth an indication that all Sulfite has been converted to Sulfate and the bath should be replaced ASAP?

Certain bacteria love sulfite solutions. These guys have been around for 3.5 billion years. They are in the group called Archaea and others will even grow in arsenite solutions. The salt content of a washing aid is not high enough to stop bacterial growth due to osmotic pressure.

 

[scheimfluger_77]

I think they should still be fine, Wade. The hardness would be due, as with all dry chemicals, to the absorption of moisture from the air. They should still be perfectly viable. I don't think atmospheric conditions deteriorate sulfite.

No, I think he's hosed. He should get rid of it... I can help.

 

[RalphLambrecht]

Quick question - is it necessary to agitate when in the Hypo Clear? Or is it best to let it sit and do what it does?

I always agitate lightly to make sure fresh solution reachea ll parts of theemulsion.

 

[hoffy]

I always agitate lightly to make sure fresh solution reachea ll parts of theemulsion.

I've never been quite sure. My process has been to give it a few sloshes when I put the print in (to make sure that the print is fully submerged) and then come back to it every few minutes and give it a few sloshes again. Generally when I have the print in the Wash Aid, I'm doing something else (I.E, I might be toning another print outside in Selenium).

Cheers

 

[mexipike]

While were on hypo discussions...

I have been using ilford wash aid lately since it's what ilford includes in it's instructions for per washing. I find it kind of expensive especially considering the fairly short life of the working solution. Is there anything special about the ilford wash aid? Or could I just use any other HCA or mix my own?
Furthermore what's a good formula for a homebrew?

 

[Oscar Carlsson]

I have a couple of questions about using HCA. Normally, I wash my prints out of the 2nd fix for about 10 minutes than soak my prints in HCA for about 15 minutes than wash 30-45 minutes. I'm going to have to change my washing work flow due the the California drought. Does soaking overnight reduce wash time? Also, I've read an article from David Vestal that it's safe to wash prints back to back in an archival print washer. I'm actually thinking about washing my prints outside so I can water my landscaping.

Your current procedure seems a bit excessive, have you tried the method outlined on the HCA package? 1 min wash after the fixer, 1-2 minutes in HCA and then 5 minutes washing in running water?

Also, this sticky thread might be of interest:

(there was a url link here which no longer exists)

EDIT: Sorry, that was the procedure for film! I've misread your post.

For prints the procedure is 1 min wash after fix (preferably using a 2 bath fixing), 2-3 min HCA and finally 20-30 minutes of washing afterwards. Ilford recommends 10 minutes of HCA and then only 5 minutes of washing.

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

 

[Rudeofus]

that's a nice story and most likely an urban mythbut, is a possible explanation.I have more trust in photographic research.

The question is: who came up with the idea to research this? Intuitively one would expect that the purest form of water would be the best washing agent, but evidence existed that impure water is much, much better. Even if some parts of the world knew that impure water is better, this bit of information may not have been present on navy ships and could have simply been discovered independently. Note that relevant research about this topic stretched well into the seventies.

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,

Its solvent character may give Sulfite an extra boost, but this property would not explain why Sodium Carbonate in water works better than deionized water. John's "Sulfite binds more eagerly to gelatin, but at the same time washes out quickly" theory may not be the whole story either. Do we know that the Sulfite washes out? Does it have to? AFAIK the biggest problem with Thiosulfate is that it will eventually disintegrate into Sulfate and Sulfur, and the latter is both yellow and attacks Silver.

@Jerry: I know they found living bacteria near volcanoes at the bottom of the ocean, and in water droplets embedded in the antarctic ice, but are these kinds of bacteria present in our own environment? AFAIK they use Sulfur Dioxide to eliminate germs in wine barrels, so it must do something to most germs around us.