myimproved HCAformula

[RalphLambrecht]

THERE IS ONE THING THAT ALWAYS BUGGED ME ABOUT the commercial versions of HCA, regardless of manufacturer;kept in partially filled bottles;stock or working solution start to smell rather terribly within a week or two.So ,Iwas looking to improve the commercial formulae and in a first attempt tried to make it closer to actual sea water by adding165gsea salt/liter of stock,resulting in 3.5% salinity for the working solution.so far ,this worked out well.my test solution is 4 weeks old now and has not developed any smell at all.Ithink this problem is solved. any commentsor further ideas on how to improve the formula?

 

[Rudeofus]

Can you elaborate what exactly the smell was like? The main ingredients of HCA that I know of are Sulfite and possibly Carbonate, and AFAIK Sulfite is a bactericide/fungicide/stufficide which should prevent any kind of mold or rot.

 

[RalphLambrecht]

Can you elaborate what exactly the smell was like? The main ingredients of HCA that I know of are Sulfite and possibly Carbonate, and AFAIK Sulfite is a bactericide/fungicide/stufficide which should prevent any kind of mold or rot.

interestingly enough. it was a distinct fowl moldy smell;awful,just the thought of itstillmakes me gag.and as my wife claims,I have a relatively high threshold for 'stink'.

 

[Vaughn]

Odd. We keep the stock solution in a drum for weeks, not air tight be any means -- never noticed any order.

 

[Rudeofus]

interestingly enough. it was a distinct fowl moldy smell;awful,just the thought of itstillmakes me gag.and as my wife claims,I have a relatively high threshold for 'stink'.

Remember that Sulfur Dioxide is used to clean out germs and fungus from wine barrels. If mold freely grows in your HCA, I wonder what it contains ...

The only other thing I could think of is that plenty of Oxygen oxidizes your Sulfite, making it more acidic and as a result liberate Sulfur Dioxide, which smells quite bad. Is there a chance you can check for pH change? If you don't have a pH meter, would addition of Sodium Carbonate to old, smelly HCA stock make the smell disappear?

 

[Gerald C Koch]

I suspect that the smell comes from bacteria growing in the solution and reducing the sulfite to other sulfur compounds. An easier solution might be to just add a bit of classic Listerine to the stock solution. The thymol will inhibit bacterial growth. I personally never save used HCA. The stuff is so cheap I really cannot see the point in doing so.

 

[RalphLambrecht]

I have a pH meter and can check,but this is not a sulfur smell;it's more like old socks.

 

[Gerald C Koch]

Not all sulfur compounds smell bad or have a sulfurous smell. There is no distinct smell for sulfur compounds. For example, carbon disulfide when pure has an ethereal odor but when impure smells rather foul.

 

[mfohl]

Wow. I've been using Kodak HCA for 30 years or so, and I never noticed any odors. I probably kept some of it too long. My paper HCA would grow what I called "slugs" after a while. That was a clue that I should get some new HCA. But never any smells.

 

[Doremus Scudder]

It's relatively easy to mix a wash aid like HCA from scratch and just mix enough for the current session. No need to mix and store gallons of stock, measure and dilute before use, etc. Maybe for a very busy or community darkroom it makes sense to mix a stock solution of wash aid. But for my one-man shop, it is a waste of time and space.

The formula I use is: 20g sodium sulfite and 0.2g sodium metabisulfite (or bisulfite) per liter. This is easily approximated by simply using a Tablespoon of sulfite and a pinch of metabisulfite per liter. If you keep your chemicals and a spoon measure handy, this is as fast or faster than diluting from a stock solution. And, you can make however much you need easily. I mix what I need and use it one shot. No smell, no worries about the sulfite oxidizing, etc.

As far as adding salt to the solution: From what I understand, seawater was used aboard ship to wash film before a final fresh water wash to save on drinking water. The seawater was found to wash more efficiently than fresh water. This led to research and a number of products, including Kodak's HCA that were even more efficient as a wash aid than seawater. I would think that going back to a salt solution or adding salt to HCA would reduce the efficiency and probably the capacity of the wash aid.

Best,

Doremus

www.DoremusScudder.com

 

[RalphLambrecht]

It's relatively easy to mix a wash aid like HCA from scratch and just mix enough for the current session. No need to mix and store gallons of stock, measure and dilute before use, etc. Maybe for a very busy or community darkroom it makes sense to mix a stock solution of wash aid. But for my one-man shop, it is a waste of time and space.

The formula I use is: 20g sodium sulfite and 0.2g sodium metabisulfite (or bisulfite) per liter. This is easily approximated by simply using a Tablespoon of sulfite and a pinch of metabisulfite per liter. If you keep your chemicals and a spoon measure handy, this is as fast or faster than diluting from a stock solution. And, you can make however much you need easily. I mix what I need and use it one shot. No smell, no worries about the sulfite oxidizing, etc.

As far as adding salt to the solution: From what I understand, seawater was used aboard ship to wash film before a final fresh water wash to save on drinking water. The seawater was found to wash more efficiently than fresh water. This led to research and a number of products, including Kodak's HCA that were even more efficient as a wash aid than seawater. I would think that going back to a salt solution or adding salt to HCA would reduce the efficiency and probably the capacity of the wash aid.

Best,

Doremus

www.DoremusScudder.com

I tested the effectiveness of the saline solution and it is as good or better than plain HCAbut without the odor.

 

[Rudeofus]

As far as adding salt to the solution: From what I understand, seawater was used aboard ship to wash film before a final fresh water wash to save on drinking water. The seawater was found to wash more efficiently than fresh water. This led to research and a number of products, including Kodak's HCA that were even more efficient as a wash aid than seawater. I would think that going back to a salt solution or adding salt to HCA would reduce the efficiency and probably the capacity of the wash aid.

If I understand Ralph correctly, the point of adding salt to his HCA stock solution is not to replace or boost the compounds already contained in commercial HCA, but to prevent the HCA stock solution from growing smelly mold/bacteria. I see no reason why it shouldn't work, as table salt in high concentrations is indeed a preservative for many food items.

 

[john_s]

I mix my HCA double strength, so working solution is made by diluting stock 1+9. More concentrated stocks tend to keep better. I discard after each session.

 

[RalphLambrecht]

I suspect that the smell comes from bacteria growing in the solution and reducing the sulfite to other sulfur compounds. An easier solution might be to just add a bit of classic Listerine to the stock solution. The thymol will inhibit bacterial growth. I personally never save used HCA. The stuff is so cheap I really cannot see the point in doing so.

how much listerine/l do you recommend?in additon to or intead of the salt?and, is there a chance the smell of listerine will stick to FB prints?:confused:

 

[RalphLambrecht]

making it fresh every time is my alternative solution is this'imprved' formula isn't working for me, but so far, so good.

 

[RalphLambrecht]

I mix my HCA double strength, so working solution is made by diluting stock 1+9. More concentrated stocks tend to keep better. I discard after each session.

wouldn't that be half strength from the recommended 1+4?

 

[Vaughn]

wouldn't that be half strength from the recommended 1+4?

I think it safe to assume that he meant that his stock solution is double-strenght.

 

[Gerald C Koch]

You would use the Listerine instead of the salt. Using Listerine is mentioned in a previous thread and would give the amount. I would try 25 ml of Listerine for a liter of HCA. The smell should leave when the print dries. As I said previously I never save used HCA Mixing your HCA as a concentrate should prevent bacterial growth as the high osmotic pressure it would create should inhibit cell growth.

You could also use a drop of phenol to replace the Listerine. There are also several commercial anti-bacterials that could be used.

 

[RalphLambrecht]

I think it safe to assume that he meant that his stock solution is double-strength.

yes, but that is a lot of sodium carbonate to dissolve in one liter.

 

[RalphLambrecht]

You would use the Listerine instead of the salt. Using Listerine is mentioned in a previous thread and would give the amount. I would try 25 ml of Listerine for a liter of HCA. The smell should leave when the print dries. As I said previously I never save used HCA Mixing your HCA as a concentrate should prevent bacterial growth as the high osmotic pressure it would create should inhibit cell growth.

You could also use a drop of phenol to replace the Listerine. There are also several commercial anti-bacterials that could be used.

I'll try that

You could also use a drop of phenol to replace the Listerine. There are also several commercial anti-bacterials that could be used.

can you name a couple. I wanted to stay away from antibiotic tp prevent me accidentially graising something really nasty.

 

[Rudeofus]

A company that would sell me Phenol told me "we can't give you a sample because we'd have to open the container and this stuff is really nasty". Hmmmm, makes me wonder whether Ralph really wants to use Phenol or similarly toxic stuff to preserve his HCA. Needless to say I did not order Phenol after that vendor's statement.

There is one simple and trivial solution to his problem, though: Final rinse for color processing. Since modern C41 does no longer need Formaldehyde, and proper E6 has the Formaldehyde in the prebleach step, final rinse contains a bactericide to preserve the processed emulsion. Since final rinse is a product geared at amateur photographers, its use should be straight forward and a lot less risky than the other compounds named here in this thread, both in terms of compatibility with photographic materials and in terms of potential health hazards.

 

[Gerald C Koch]

A company that would sell me Phenol told me "we can't give you a sample because we'd have to open the container and this stuff is really nasty". Hmmmm, makes me wonder whether Ralph really wants to use Phenol or similarly toxic stuff to preserve his HCA.

Phenol is a deliquescent solid but usually encountered as a liquid containing 8% water. I would be careful to avoid contact with concentrated phenol as it can cause burns. However dilute phenol is approved for use in many medications. One use is as a preservative for injectables such as insulin and vaccines.

 

[RalphLambrecht]

Why carbonate? HCA is typically sulfite with either some bisulfite to make it less alkaline (to lessen swelling) and/or sulfate (also to lessen swelling but by a different mechanism).

For reference, here is what Ilford currently lists in its liquid packaged Washaid:

Sodium Lauryl Ether Sulfate
DTPA (sequestering agent)
Sodium Sulfite
Polydimethyl Siloxane Emulsion
Water

And Kodak lists the following in its Hypo Clearing Agent MSDS (not necessarily complete)

Sodium Sulfite
Sodium Metabisulfite
Sodium Citrate
EDTA Tetrasodium Salt

to my knowledge Agfa recommended 2% sodiun crbonate while Ilford and Kodak recommended 2%sodium sulfite as you statedbut don't know why the differece.

 

[john_s]

I think it safe to assume that he meant that his stock solution is double-strenght.

Correct. My apologies for not making that clear in the first place. It is close to the maximum concentration of sodium sulphite solution, around 200g/L.

 

[Vaughn]

Correct. My apologies for not making that clear in the first place. It is close to the maximum concentration of sodium sulphite solution, around 200g/L.

No worries, mate. I was married to an Aussie for 25 years so perhaps I have gained a bit of understanding of the breed.