HT-2 Hypo Estimator Query

[dancqu]

Dancqu, can you say more about the Ilford test?
Is it a published formula like Kodak's HT-2 or is
it a packaged product? If it is a formula, could
you post the formula here? Thanks!

From the; Ilford Manual of Photography, 5th Edition,
1958. Formula; 1% solution of silver nitrate.

I allow the staggered drops three minutes then blot.
Examine immediately after. Or, the paper may be
washed. With excess silver nitrate removed the
spots will not darken. Dan

[CBG]

That's a pretty simple formula.

Thanks!

[Photo Engineer]

I'm not sure how plain Silver Nitrate vs Silver Nitrate in Acetic Acid are any better or worse. The latter is used in most cases and has been in use for over 100 years.

PE

[Raphael]

Hi all,

I revive this old thread because I am back to FB printing, and tried to use again an HT-2 test bottle I made two years ago. From memory, I followed the Unblinkingeye website formula.

Of course, this HT-2 tester was stored in a full, well stopped, brown glass bottle, in obscurity, but I was concerned by the shelf life of this product.
I found this thread here, and I agreed the better way is to test it, with a very quickly washed FB test print.

Reading, in the excellent "Way Beyond Monochrome" book, that the test should be made in subdued light, I interpreted it (maybe mistakenly), that it can be conducted in red, safe darkroom light...

So I was a little puzzled, when, for the five spot of HT2 tester I placed on the quickly washed sheet (Forte Fortezo Museum paper...), after 5 minutes, absolutely no one let any stains at all !

So, my question : Is "actinic" non-red light is mandatory when HT2 testing ? If yes, how the ambiant available light affect the test result ?

In advance, thanks you,

Best regards,

Raphael

[Photo Engineer]

The stain cannot be seen under red light. It must be viewed under dim white light to be visible.

I have found that it can last for years as long as the solution itself does not turn brown.

PE

[Martin Aislabie]

The stain cannot be seen under red light. It must be viewed under dim white light to be visible.

I have found that it can last for years as long as the solution itself does not turn brown.

PE

Thats good news

I have some 2 year old HT2 and was wondering if I should replace it

Thanks

Martin

[Raphael]

The stain cannot be seen under red light. It must be viewed under dim white light to be visible.

I have found that it can last for years as long as the solution itself does not turn brown.

PE

Many Thanks, PE, it's good to know about the keeping properties. Especially if one knows the current price of Silver Nitrate.

However, probably I have a slow brain, but I persist to be confused why I didn't see coloured spots of the test sheet I made : I didn't see them, even when putting the sheet in white light !

So, the question I ask : is actinic white light (even faint) is mandatory, during the two minutes after put one drop of HT2 ? If not, it's means that my HT2 bottle is probably gone bad.

Another remark : in "Way beyond monochrome book", they say HT2 should be conducted on a damp print, and the HT2 Kodak note (J11-1985) stats that the print should be dry ! Who is right ?

Again in Way beyond book, it is said that the test can be "fixed" for posterior reference with salted water. How does it work ? I processed this way with my test sheet, before switching the white light on, does it explain why I got no stains ?

Many thanks in advance,

Best,

Raphael

[Photo Engineer]

Raphael;

Ok, this is Silver Nitrate in Acetic acid. It tests for retained hypo. It forms a brownish red stain in the presence of hypo and Silver complexes which cannot be seen in red light. The Kodak instructions that I have are not specific to wet or dry. They are vague. They are vague also as to the lighting conditions. I have several sets of documents though so I'll look more.

Anyhow, Silver Nitrate in acid and in excess of that needed to react with a halide will form this color, but the color is not fully evident until exposed to ambient white light. If you leave a well washed print out in the light, and with this test solution on it, the tested area on the print will also darken even if clean, so extended white light can give a false positive! The color from the test solution that is valid shows up within the first 5 minutes or less. It is called "printout".

It is akin to what happens if you put a drop of Silver Nitrate on your finger (not recommended) and expose it to light. Your finger turns dark brownish black.

So, one drop on a white area on a print. Expose to light and over 5 mins if you see a dark brown red stain, the wash is insufficient. If it is good, you see no color or a light yellow. If this "good" print is left in the light for a few minutes to several hours it will turn as dark as a "failed" print test.

PE

[Raphael]

Hi PE,

Many thanks for your extensive and clear reply !

I understand now better why I hadn't get any stains with my way of testing.

I presume than one of your document is this Kodak .pdf, I used it for reference.

Again, thanks you very much,

Regards,

Raphael

[Photo Engineer]

I have a Kodak PDF, a Kodah How To book and the packing stuffer from a box of the chemistry. So I have 3.

PE