[rollei_list] Re: Rollie R3 film
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <rollei_list@xxxxxxxxxxxxx>
- Date: Mon, 30 Jul 2007 17:19:10 -0700
----- Original Message -----
From: "Carlos Manuel Freaza" <cmfreaza@xxxxxxxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Monday, July 30, 2007 2:31 PM
Subject: [rollei_list] Re: Rollie R3 film
Richard, the film base support for the R3 is
polyester, not cellulose and it is one of the most
advanced films made today.
Multiple layer emulsions are not new. They have been
used for decades to extend the density range of the film and
tailor the characteristic curve. Multiple layers are also
used in some color films. Agfa, for instance had two or
three layers for each color. I think this was partly to
control the curve shape but may also have been to allow
different couplers in each coating.
If R-3 is based on Agfa technology it likely has more
than three layers. Agfa also included separator layers. They
may not be needed in a B&W silver film. Some of their films
had something like 12 or 14 layers. All of these must be
extraordinarly thin, the coating technology is quite awe
inspiring.
Most color films have the anti-halation layer under the
emulsion. It is indeed a better way to do it than including
a dye in the back coating and also eliminates problems with
light-piping. Light piping is why 35mm B&W negative films
have a pigment in the support, the under the emulsion
anti-halation layer eliminates the need for this.
However, there is probably still a back coating to
reduce curling. Curling is due to the difference in
expansion/contraction of the emulsion and support.
The use of a polyester support, such as Kodak Estar,
results in excellent dimentional stability plus the material
is supposed to be much more resistant to change with time
than any of the cellulose bases. However, it still requires
subbing to make the emulsion stick to it.
Somehow the roll under discussion got subjected to
something that made the entire emulsion and back coating
come off. The emulsion will come off in one piece even
though it is made up of several coatings.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
---
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