Kodak HT-2 residual hypo test

[Mainecoonmaniac]

I'd like to mix up some some Kodak HT-2 to check for residual fixer on my FB prints. This recipe calls for 28% acetic acid. Can I substitute citric acid? I have a bunch I use for my stop bath already.

http://unblinkingeye.com/Articles/Archival/archival.html

 

[tezzasmall]

I presume that since since there have been no replies since 2014, and my searching has not unearthed anything, I guess the answer is NO?

Terry S

 

[Mainecoonmaniac]

I guess the answer is "no". But I ordered concentrated acetic acid and made a batch residual hypo test and have been using for a few years. Works great. But concentrated acetic is VERY strong. I wore gloves and mixed in a very well ventilated darkroom. The test last a long time since I use only a few drops per print session.

 

[Doremus Scudder]

According to my calculation, the concentration of acetic acid in the final HT-2 test solution is 3.5%. I would imagine that arriving at that number by any means would yield the correct test solution, i.e., a 3.5% acetic acid solution with the addition of 7.5g of silver nitrate crystals. If you had a weaker solution of acetic acid to start with, you'd just have to do the arithmetic to arrive at the right volume of the acetic acid solution to add.

Best,

Doremus

 

[Photo Engineer]

The answer is indeed... NO!

PE

 

[tezzasmall]

And who said that resurrecting old threads didn't achieve anything?

I'm glad though that the OP has seen the answers above.

Terry S

 

[koraks]

Cleaning vinegar is around 7-8% acetic acid and that's what I always use for photographic purposes. Easier to get and a little less annoying to work with than e.g. glacial acetic acid.

I suppose citric acid won't work in this application as it's a chelating agent.

 

[Photo Engineer]

Do not use Citric Acid!

Use the exact formula as given.

PE

 

[Doremus Scudder]

Do not use Citric Acid! Use the exact formula as given. PE

Ron,

Certainly citric acid should not be used, but is there any reason that a weaker dilution of acetic acid cannot be used to mix the working solution as long as the concentration of acetic acid remains the same in the working solution? I can't see any.

Best,

Doremus

 

[Photo Engineer]

Ok, I should clarify this. Going through it in my mind, I envisioned scenarios in which the final Silver Nitrate concentration was too low to be useful. That is the problem here, and a non-chemist might make an error in calculation that ruins the final mix.

That is my only point.

PE

 

[Mainecoonmaniac]

PE has the final say. I'm non-chemist seeking answers. Happy Holidays all!

 

[grain elevator]

I've made my first batch of HT-2 with distilled vinegar that is 25% acetic acid, adjusting the ratio with water accordingly. It seems to work just fine. My concern wasn't the concentration (even though it's possible I screwed it up very slightly due to the volume or weight percentage issue, but it's probably not too critical), but possible presence of impurities.

 

[Fatih Ayoglu]

Can I do create HT-2 with white vinegar? The only thing is, I dont know what acidity it has?

 

[koraks]

Can I do create HT-2 with white vinegar?

In theory, yes, but I'd make sure it's as pure as possible - not flavored etc. Vinegar intended for human consumption is usually around 4%. Cleaning vinegar is around 8% or so. I usually the latter for photographic purposes. I've never tried to make HT2, though.

The main problem in this particular application will be that store-bought vinegar is likely to contain at least some chloride ions. These will react with some of the silver nitrate to form silver chloride, which will show up as a milky cloudiness. You'd have to expose the solution to strong UV light to 'print out' the silver chloride and then let the black residue settle to the bottom of the vessel. Filter before use through a fine mesh filter (e.g. paper).

 

[Fatih Ayoglu]

In theory, yes, but I'd make sure it's as pure as possible - not flavored etc. Vinegar intended for human consumption is usually around 4%. Cleaning vinegar is around 8% or so. I usually the latter for photographic purposes. I've never tried to make HT2, though.

The main problem in this particular application will be that store-bought vinegar is likely to contain at least some chloride ions. These will react with some of the silver nitrate to form silver chloride, which will show up as a milky cloudiness. You'd have to expose the solution to strong UV light to 'print out' the silver chloride and then let the black residue settle to the bottom of the vessel. Filter before use through a fine mesh filter (e.g. paper).

Just checked, it says 5% white vinegar, no mention about chloride but then it might be low enough.
Found this Acidic Acid

I think that might work.

 

[koraks]

no mention about chloride

It may or may not be in there.

Found this Acidic Acid

I use something like that, only weaker - 8%. Mine is clean/no chlorine.

 

[grain elevator]

The batch I made with 25% distilled vinegar and commented about above, three years ago, still worked a few months ago. No problem with cloudiness - whether or not there is any is hard to see because it's in a dark bottle, but in use there is no issue.

 

[grain elevator]

Found this Acidic Acid

I don't think it's likely that this is any purer than the stuff for culinary/household use.

 

[koraks]

I don't think it's likely that this is any purer than the stuff for culinary/household use.

The thought that they might be different isn't so far-fetched though. The distilled industrial stuff is likely to be made with demineralized water to prevent scaling in the process equipment. The dilute stuff for household/kitchen use can very well be diluted with source/tap water, which will contain chlorine.