Hypo Test HT-2 : something wrong or what ?

[Raphael]

Hi all,

I plunged again in Chemistry and made my own HT-2 test solution, from the well known formula (i.e from Ed Buffaloe's Unblinking Eye).

I mixed the component, acetic acid, silver Nitrate, water, on a small brown glass bottle, keeped in the basement (in darkness). One day later, I tested it on two prints, one RC and one Fiber base.

With the RC print, I left the HT-2 drop two minutes, rinced, and I obtained... nothing, nada, rien ! Not even the slightest spot where I droped the HT-2...

On the Fiber base print (a completely messed up print, quickly washed, keep for test purpose), I obtained a stain, but a light grey one, rather than the "tea" stain described everywhere.

So, frome here, there are a few hypothesis :

- Nothing is bad with the Test solution : my prints are very well washed ! I can understand it with the RC print, since it is very easy to wash, but I have doubts for the FB.

- Water used for the solution was improper : I read that the water should be demineralized, but I used very low mineralized drinking water instead. Indeed, there was a light white precipitate in the bottle when I mixed the solution.

- I mess completely with acetic acid concentration : Formula says acid must be at 28%. I guess that this concentration is given in mass. All I have in my chemicals, is acetic acid at 80% in volume. I approximate the 28% acid with mixing 11 ml concentrated acid (80%) with 30 ml water. I know this is crude reasoning (I mix mass and volume concentration), but given the density of acetic acid (1.08 water relative), I think I am right with that.

- There is specific places on print where put the test drop : Are the white margins (i.e not exposed to light during printing process) are OK ?

- There is specific environment issues : tests was made in very moderate light, and under rather cool ambient temperature.

Is the HT-2 solution making is so tricky that I completely missed the point here, with the above approximations ? :confused:

Sorry for the long post, but any thoughts will be greatly appreciated.

Regards,

Raphael

 

[Ryuji]

What you described are largely correct and I don't know what's wrong from it.

Make another FB test strip that is washed no more than 2 minutes and try the solution.

The test reaction may take a minute or two.

Another thing is that I'd try to bring the test strip come to room temp 20-27˚C before applying the test.

 

[dancqu]

[QUOTES=Raphael;389547]
...HT-2 test solution, from the well known formula ...[/QUOTE]

An Ilford formula calls for 1% silver nitrate solution. An Edwal
formula is also 1% silver nitrate but includes 30% of 10% by
volume acetic acid: 1 gram silver nitrate + 30ml of 10%
acetic acid to make 100ml of test solution. Good I'd
say for 1000 plus tests.

Here's another approach. I've 1.05 grams silver nitrate
in one 35ml amber glass bottle; 3%. Another same bottle
contains 5% Heinz white vinegar. The formulas are
drop wise; eg, one drop each silver, water, acid.

Likely the silver nitrate solution is blue sensitive only
so a yellow or orange safe light is OK. Be sure to blot
dry. Evaluate quickly under low level white light. Dan

 

[Raphael]

Ryuji, Dancqu, thanks you very much for your replies.

An Ilford formula calls for 1% silver nitrate solution. An Edwal
formula is also 1% silver nitrate but includes 30% of 10% by
volume acetic acid: 1 gram silver nitrate + 30ml of 10%
acetic acid to make 100ml of test solution. Good I'd
say for 1000 plus tests.

If I understand correctly, exact formula does not seems critical. At unblinkingeye (and somewhere else), the formula adapted for 250 ml is :
- 32 ml 28% acetic acid
- 1.87g Silver Nitrate
- water to complete up to 250ml

Ryuji, thanks to talk about the temperature option, since temp in my basement is currnetly a way low (around 15°C).

I should try again.

Regards,

Raphael