I think I can confirm Richard's information. I dug through some very old Kodak
literature and found some information that long ago Kodak had a blue sensitive
motion picture film that is within that ASA speed. It was used for creating
motion picture titles, etc. Perhaps because it was motion picture stock, there
is no identifying information on the film. Not much information, except it was
daylight only film, not tungsten. Understandably being blue sensitive. It was
extremely fine grained.
Thinking back on the old RKO B&W movie films and others as seen on television
as reruns these days, the titles were always white lettering on the screen. How
that might relate to the overall process, I'm not sure.
________________________________
From: pure-silver-bounce@xxxxxxxxxxxxx <pure-silver-bounce@xxxxxxxxxxxxx> on
behalf of `Richard Knoppow <dickburk@xxxxxxxxxxxxx>
Sent: Friday, October 15, 2021 4:06 PM
To: pure-silver@xxxxxxxxxxxxx <pure-silver@xxxxxxxxxxxxx>
Subject: [pure-silver] Re: ISO 4 Direct Positive Orthochromatic film
Also, the films I am thinking about, either direct positive
or the release positive, were not orthochromatic but color blind,
i.e. sensitive only to blue and near UV.
On 10/15/2021 1:02 PM, `Richard Knoppow wrote:
My memory is not what it used to be so I don't remember
details. You may know there is an effect where if an emulsion
is seriously overexposed it reverses the image. This effect was
used to make direct positive material. I am pretty sure Kodak
and others made such films for either document copying or for
making duplicate negatives or duplicate release prints where
only the original positive was availabe (or from a reversal
film). I am just drawing blanks on the name of the material or
even the name of the effect it made use of. I am hoping someone
else here has enough of a clue to remember. Meanwhile I will
look at what documentation I have to get a reminder. ISO-4 is
in the range of fast enlarging paper or positive films. If you
developed a clip what did you get? If I am right it should have
come out black and a clip exposed to strong light should come
out clear.
It is the term "direct positive" that leads me to think it
might be this stuff. If, however, its just "positive" its
probably something like Kodak Fine Grain Release Positive, a
film originally intended to make release prints of B&W movies.
This is a very slow film, ISO-4 would make sense for it, with
an emulsion similar to fast printing paper like the late,
lamented, Kodabromide. There is likely still data on it on line
and similar film may still be made because it was also used to
make masks (or matts) for motion picture special effects and
titles. It can be processed in any fairly active developer like
paper developer or D-19.
On 10/15/2021 12:38 PM, Martin magid wrote:
I developed a strip, and there is nothing printed on the edges.
Now what?
Marty
