Are Paper Speeds Slow Due to the Thin Emulsion?

PATRICK GAINER wrote

When I use HC110 for paper, I spice it up by adding
some carbonate.

The silver content of paper and the thickness of the emulsion
can both be much less than those of film because light passes
through the silver image twice.


That "...light passes through the silver image twice" is the
part that bothers me. Below you do not use that phrase. Below you
describe what is actually going on.
So, by absorbtion the light intensity is diminished once by
transmission and twice by reflection. A good black will likely
reflect from it's surface more light than will emerge from it's
surface after two passes.
That "much less" silver in a paper emulsion has me thinking of
the "silver rich" papers on the market. Perhaps selenium's addition
of mass to the image accounts for the deeper blacks on some papers.
Good the subject came up. I'd given it no thought. Dan



No, I'm saying that the same amount of silver per unit area will produce
a higher reflected density than tramsmission density. All you have to do
to prove that to yourself is look at a negative by transmitted light and
then lay it on white paper and see how much darker it is. Thus, paper
requires less silver per unit area to produce a given density than does
a transparency.

PATRICK GAINER wrote

When I use HC110 for paper, I spice it up by adding
some carbonate.

The silver content of paper and the thickness of the emulsion
can both be much less than those of film because light passes
through the silver image twice.


That "...light passes through the silver image twice" is the
part that bothers me. Below you do not use that phrase. Below you
describe what is actually going on.
So, by absorbtion the light intensity is diminished once by
transmission and twice by reflection. A good black will likely
reflect from it's surface more light than will emerge from it's
surface after two passes.
That "much less" silver in a paper emulsion has me thinking of
the "silver rich" papers on the market. Perhaps selenium's addition
of mass to the image accounts for the deeper blacks on some papers.
Good the subject came up. I'd given it no thought. Dan



No, I'm saying that the same amount of silver per unit area will produce
a higher reflected density than tramsmission density. All you have to do
to prove that to yourself is look at a negative by transmitted light and
then lay it on white paper and see how much darker it is. Thus, paper
requires less silver per unit area to produce a given density than does
a transparency.

"Jorge Omar" wrote in message
...
Richard

Out of curiosity, what kind of developers are used with
these films (fine
grin, high energy, etc)

Thanks,

Jorge

(Richard Knoppow) wrote in
om:

Some films do have very thick emulsions because they
are needed.
The best example is the "film" made for nuclear track
recording.
Because the particles these films are intended to trace
pass through
the emulsion very efficiently the emulsion must be very
thick to stand
a chance of some particals colliding with the crystals
in the
emulsion. This stuff is very specialized and the
conditions for its
operation are very little related to normal pictorial
film.

Richard Knoppow
Los Angeles, CA, USA



I don't remember what Kodak used on their films, my
memory is that its something along the lines of D-19. I do
know that the fixer must be special and that these very
thick emulsions are difficult to fix out and wash.


--
---
Richard Knoppow
Los Angeles, CA, USA

Thanks again, Richard

Jorge

"Richard Knoppow" wrote in news:2ofn51Fa9jl6U2
@uni-berlin.de:


I don't remember what Kodak used on their films, my
memory is that its something along the lines of D-19. I do
know that the fixer must be special and that these very
thick emulsions are difficult to fix out and wash.

Thanks again, Richard

Jorge

"Richard Knoppow" wrote in news:2ofn51Fa9jl6U2
@uni-berlin.de:


I don't remember what Kodak used on their films, my
memory is that its something along the lines of D-19. I do
know that the fixer must be special and that these very
thick emulsions are difficult to fix out and wash.