Kodak HT-2 residual hypo test

Mainecoonmaniac

Member
Joined
Dec 10, 2009
Messages
6,297
Format
Multi Format

tezzasmall

Member
Joined
Dec 29, 2013
Messages
1,127
Location
Southend on Sea Essex UK
Format
Plastic Cameras
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
 
OP
OP

Mainecoonmaniac

Member
Joined
Dec 10, 2009
Messages
6,297
Format
Multi Format
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

Member
Joined
Sep 10, 2002
Messages
3,582
Location
Eugene, Oregon
Format
4x5 Format
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
 

koraks

Moderator
Moderator
Joined
Nov 29, 2018
Messages
22,030
Location
Europe
Format
Multi Format
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.
 

Doremus Scudder

Member
Joined
Sep 10, 2002
Messages
3,582
Location
Eugene, Oregon
Format
4x5 Format
Photo Engineer said:
Do not use Citric Acid! Use the exact formula as given. PE
Click to expand...

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

Subscriber
Joined
Apr 19, 2005
Messages
29,018
Location
Rochester, NY
Format
Multi Format
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
 
OP
OP

Mainecoonmaniac

Member
Joined
Dec 10, 2009
Messages
6,297
Format
Multi Format
PE has the final say. I'm non-chemist seeking answers. Happy Holidays all!
 

grain elevator

Member
Joined
Jan 31, 2020
Messages
1,279
Location
Germany
Format
Multi Format
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.
 

koraks

Moderator
Moderator
Joined
Nov 29, 2018
Messages
22,030
Location
Europe
Format
Multi Format
Fatih Ayoglu said:
Can I do create HT-2 with white vinegar?
Click to expand...

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

Member
Joined
Apr 11, 2021
Messages
446
Location
Birmingham, UK
Format
Analog

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.
 

grain elevator

Member
Joined
Jan 31, 2020
Messages
1,279
Location
Germany
Format
Multi Format
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.
 

koraks

Moderator
Moderator
Joined
Nov 29, 2018
Messages
22,030
Location
Europe
Format
Multi Format
grain elevator said:
I don't think it's likely that this is any purer than the stuff for culinary/household use.
Click to expand...

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.
 
You must log in or register to reply here.
Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…