From: Craig Zammiello (zamm@optonline.net)
Date: 06/10/03-06:32:02 AM Z
----- Original Message -----
From: Katharine Thayer <kthayer@pacifier.com>
To: <alt-photo-process-l@skyway.usask.ca>
Sent: Monday, June 09, 2003 2:50 PM
Subject: Re: digital negs & Epson backlight film
> Christina Z. Anderson wrote:
> >
> > > Judy and Christina - Epson Back Light Film is made of mylar, which
> > > completely blocks UV (in other words, it is a UV filter, and will
appear
> > > black in UV light). I don't know what the Kodak film is, but since
most of
> > > their films are either of acetate or poly plastics, they should not
block
> > > UV transmission.
> > > ---sil
> > > Sil Horwitz, FPSA
Sil, most Kodak con-tone films for Positive and Negative work (contacting
like we do ) were made on what they referred to as an Estar base. All of the
films used for color separation and copy work and black and white positive
contact work (such as Gravure Positive film and Commercial film 4127) also
had a "anti-halation" layer incorporated into the base which stopped the
scatter of light that could bounce back up through the base when contacting
films in a vacuum frame.
As for Mylar blocking UV light, I'm sure it blocks a part of the spectrum,
but I don't think it affects most of the process that we all use. I have
been using Mylar as direct working material in both Photogravure (which
favors the low band spectrum, being a dichromate based process) and photo
Litho plates (which favor the high band spectrum, being a diazo based
process. So, the frequency of UV blocked would probably not apply to most
Alt. Processes.
I do have UV filter material that does indeed block UV, and believe me,
Mylar is nowhere near this material.
Cheers, Craig Z
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