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Hypersensitization

Many amateurs hyper their films by its own. Most use a so called Forming gas, a mixture of 10% hydrogen and 90% nitrogen (Forming gas is also available as a 8 to 92% mixture). Others use pure hydrogen (as me) which has some advantages and some disadvantages. I explain the hypering process as I do. If you want to use Forming gas you must change only the parameters (e.g. pressure, temperatur, hypering time).

Some explanations to the hypering process:

Hypersensitization is a process that effects the films Schwarzschild value as as a result, the film provides its sensitivity during the hole time of exposing the film. Normally the films sensitivity drops down to a ver low value after starting the exposure (this decrease of sensitivity is known as Schwarzschild effect).

The process in its steps (my parameters and 100% hydrogen):

Put the film onto a reel and put the hole into a light and gas tight tank (in total darkness of course).
Create a vacuum to remove the oxygen out of the tank. Then fill the gas into the tank up to a pressure of 1.1 bar.
Heat the tank up to about 57 °C and back the film for about 8 hours 15 minutes.
After backing the film, remove the gas and wait until the tank cools down to normal room temperature.
Then remove the film out of the tank. Keep the hypered film in your refrigerator at -25 degrees centrigrade.
Hypered TP 2415 can be stored at -25 degrees centigrade for about 1 year without loosing its sensitivity.

My parameters for hypering Technical Pan 2415 are:

- 100 % hydrogen
- 1.1 bar pressure at 20 °C temperature
- 56 - 58 °C temperature
- 8 hours 15 minutes backing time

During hypering the film the pressure inside of the tank increases to about 1.3 - 1.4 bar.
That's ok. Hydrogen is very explosive and you must handle it carefully. But if you handle it correct nothing will happen.
I have used pure hydrogen since 1991 and have had no problems and I'm very satisfied with the results.

Because hydrogen has some big advantages against Forming gas. When you use hydrogen, your film gets a bit more sensitive and a bit faster, as well as the film won't get foggy (or darker) during storage.
And the hypering process is much faster ( 8 hours against 24 hours) . After hypering, TP 2415 is very sensitive against bends. So be careful.