Does HT2 work for Negs as well as Prints

[Martin Aislabie]

Guys, I am experimenting with processing 2 sheets of film placed back to back with some drying screen sandwiched between the two (to allow the chemicals to access the anti-halation layer) in a CombiPlan Tank

On another thread, someone has suggested using this method there might be problems with residual fixer and inadequate washing of the backing layer.

Will a HT2 test for residual thiosulphate work for Film as it does for Paper?

Is there any other way to check for adequate washing?

I don't expect there to be a problem but would hate to be disappointed in years to come.

The 2 sheets of sandwiched film (HP5/Delta 100) are clear in the Fixer (Hypam at 1+4) within 60sec (the time I turn the lights on to look)

Thanks

Martin

 

[RalphLambrecht]

...Will a HT2 test for residual thiosulphate work for Film as it does for Paper?...

No. Since it depends on the severity of the stain, it works with paper only.

...Is there any other way to check for adequate washing?...

Yes. The most reliable test is the methylenen-blue test, but it is hardly realistic outside a professional lab. I can, however, recommend the HT1 test. This test has fallen out of favor with many users, but appropriately applied, it gives rather useful results for film washing.

 

[Martin Aislabie]

Thanks Ralph

Making up the solution looks reaonably straight forward (famous last words)

One final question - the last wash water - is it worth leaving the film to stand in the last wash water for say 5 mins, so any residual chemicals can diffuse into the water ?

I wash in running water - so cannot see there being any detectable concentration

Regards

Martin

 

[RalphLambrecht]

Thanks Ralph

Making up the solution looks reaonably straight forward (famous last words)

One final question - the last wash water - is it worth leaving the film to stand in the last wash water for say 5 mins, so any residual chemicals can diffuse into the water ?

I wash in running water - so cannot see there being any detectable concentration

Regards

Martin

Yes, that's exactly how it was meant.

 

[Martin Aislabie]

Yes, that's exactly how it was meant.

Thanks

Martin

 

[Kirk Keyes]

I've done the methylene blue test, in a lab, and I would not recommend it for home use.

It uses sodium borohydride which has a Saf-T-Data rating of:
Health Rating: 3 - Severe
Flammability Rating: 3 - Severe (Flammable)
Reactivity Rating: 3 - Severe (Water Reactive)
Contact Rating: 3 - Severe

That said, borohydride is rather nasty...

 

[dancqu]

P. K Turner Has Suggested ....

After first rinsing wash the film with water made
pink with potassium permanganate. If the solution
remains pink washing is complete. The test can be
used to check already washed film. Or prints?

Potassium permanganate is a HazMat chemical;
at least from P. Formulary. Dan