Re: [APML] Medium Format TP...worth messing with?

[KGKIRKLEY@aol.com]

In a message dated 3/25/04 1:31:37 PM, s-walters@comcast.net writes:

<< For a while, everyone was putting TP on reels for hypering to avoid this.

But Kodak changed the formulation some years ago and this is not necessary.

I found that hypering 120 TP worked fine as long as you do not remove the

paper before hypering. If you do that, areas of the film will not be hypered

evenly. I have a vacuum back on my camera so I first hyper, then remove the

paper.


Steve...

http://www.StarryNights.us >>

Steve:
I hear what you say but that doesn't make any sense.

Actually it didn't make any difference whether you hypered the 120 Tech Pan 
with or without the backing. The problem was the inks used to print the paper 
backing. For many years the inks were solvent based, but Kodak changed to water 
based inks.
This resulted in the retained moisture in the inks on the paper backing 
affecting the Tech Pan emulsion when the film was hypered. The presence of moisture 
will cause a base fog in hypered Tech Pan. The base fog showed up where the 
inks touched the film.

The type of hypering affected the film more; ie. Low vacuum dessication and 
hypering didn't show the 'print thru'. High (med. actually) vaccum dessication 
and hypering did show the 'print thru'.

Kent Kirkley
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