Are Paper Speeds Slow Due to the Thin Emulsion?

At least according to conventional wisdom slow films have thin
emulsions and fast films have thick emulsions. I know from tests
done that a 120 roll of slow Pan F+ has much more silver content
than an equivalent area of print paper. I do not know a paper's
film equivalent ISO but the Pan F+ ISO is likely 6 to 10
times greater.

Mr. Knoppow has mentioned the extreme fine grain of paper emulsions.
In itself that supports the idea of papers having thin emulsions.
In fact IIRC, he has compared very slow micofilm emulsions to
print paper emulsions.

I suggest that paper is slow because it has a very thin emulsion and
little silver. I'd like to know more of the relationship because I'm
about to do some film developer tests using print paper. I think
the correspondence may be great thereby making for valid tests.

I'm hoping some others will shed more light. Dan

"Dan Quinn" wrote in message
om...
[...] I'd like to know more of the relationship because I'm
about to do some film developer tests using print paper. I think
the correspondence may be great thereby making for valid tests.

Print developer for printing paper? May I ask why?

"Dan Quinn" wrote in message
om...
[...] I'd like to know more of the relationship because I'm
about to do some film developer tests using print paper. I think
the correspondence may be great thereby making for valid tests.

Print developer for printing paper? May I ask why?

Print papers are obviously slow, because it is desirable
to enable burning dodging and other print controls.

The speed of papers are typically the result of two factors
content-amount of bromide & content amount of chloride.

Every paper could have the same content of silver and granularity, but
if you vary chloride and bromide you will have very different results,
some slower some faster depending on the proportions.



In article ,
(Dan Quinn) wrote:

At least according to conventional wisdom slow films have thin
emulsions and fast films have thick emulsions. I know from tests
done that a 120 roll of slow Pan F+ has much more silver content
than an equivalent area of print paper. I do not know a paper's
film equivalent ISO but the Pan F+ ISO is likely 6 to 10
times greater.

Mr. Knoppow has mentioned the extreme fine grain of paper emulsions.
In itself that supports the idea of papers having thin emulsions.
In fact IIRC, he has compared very slow micofilm emulsions to
print paper emulsions.

I suggest that paper is slow because it has a very thin emulsion and
little silver. I'd like to know more of the relationship because I'm
about to do some film developer tests using print paper. I think
the correspondence may be great thereby making for valid tests.

I'm hoping some others will shed more light. Dan

--
LF Website @ http://members.verizon.net/~gregoryblank

"To announce that there must be no criticism of the President,
or that we are to stand by the President, right or wrong,
is not only unpatriotic and servile, but is morally treasonable
to the American public."--Theodore Roosevelt, May 7, 1918

Print papers are obviously slow, because it is desirable
to enable burning dodging and other print controls.

The speed of papers are typically the result of two factors
content-amount of bromide & content amount of chloride.

Every paper could have the same content of silver and granularity, but
if you vary chloride and bromide you will have very different results,
some slower some faster depending on the proportions.



In article ,
(Dan Quinn) wrote:

At least according to conventional wisdom slow films have thin
emulsions and fast films have thick emulsions. I know from tests
done that a 120 roll of slow Pan F+ has much more silver content
than an equivalent area of print paper. I do not know a paper's
film equivalent ISO but the Pan F+ ISO is likely 6 to 10
times greater.

Mr. Knoppow has mentioned the extreme fine grain of paper emulsions.
In itself that supports the idea of papers having thin emulsions.
In fact IIRC, he has compared very slow micofilm emulsions to
print paper emulsions.

I suggest that paper is slow because it has a very thin emulsion and
little silver. I'd like to know more of the relationship because I'm
about to do some film developer tests using print paper. I think
the correspondence may be great thereby making for valid tests.

I'm hoping some others will shed more light. Dan

--
LF Website @ http://members.verizon.net/~gregoryblank

"To announce that there must be no criticism of the President,
or that we are to stand by the President, right or wrong,
is not only unpatriotic and servile, but is morally treasonable
to the American public."--Theodore Roosevelt, May 7, 1918

"Dan Quinn" wrote in message
om...
At least according to conventional wisdom slow films have
thin
emulsions and fast films have thick emulsions. I know from
tests
done that a 120 roll of slow Pan F+ has much more silver
content
than an equivalent area of print paper. I do not know a
paper's
film equivalent ISO but the Pan F+ ISO is likely 6 to 10
times greater.

Mr. Knoppow has mentioned the extreme fine grain of paper
emulsions.
In itself that supports the idea of papers having thin
emulsions.
In fact IIRC, he has compared very slow micofilm emulsions
to
print paper emulsions.

I suggest that paper is slow because it has a very thin
emulsion and
little silver. I'd like to know more of the relationship
because I'm
about to do some film developer tests using print paper. I
think
the correspondence may be great thereby making for valid
tests.

I'm hoping some others will shed more light.
Dan

The conventional wisdom is wrong. Emulsion speed has
nothing to do with thickness. It is mainly a function of the
way the emulsion is made and sensitized. There are so many
factors affecting speed that its difficult to name them all
but the more important ones are the kind of silver halide
used (Silver Iodide is fastest and is usually combined with
Silver bromide in film), the exact way the halides are
injected into the gelatin, this affects the crystal shape.
The way the emulsion is ripened and how many ripenings it
gets. Also very important are trace materials added to the
emulsion. Certain metals increase speed, Gold is an
important one but cadmium and others are also used. Silver
halide is sensitive to blue and near UV light. Silver Iodide
to blue green. To sensitize the film to other colors dyes or
combinations of dyes are added. Other ingredients of the
emulsion also affect speed. These include silver sulfide and
ammonia. High speed emulsons also reqire effective anti-fog
agents and stabilizers.
Paper emulsions are made from (usually) a mixture of
Silver Chloride and Silver Bromide. Variable contrast paper
probably has some Silver iodide in it as well. The emulsions
are made differently. They are ripened less and are washed
differently. They may not contain some of the sensitizing
agents found in film.
Paper emulsion is thin because it does not have to be
thick to get sufficient density. This is because the light
must go through it twice. Film emulsion is not that thick
either. In the past many films were double coated with a
fast emulion and a slower one of different contrasts. This
extended the exposure range of the film. Modern emulsion
making technique allows equally great latitude with a single
coating. The coating can also be thinner. In a film this has
the advantage that there is less spreading out of light
within the emulsion. This spreading, due to scattering from
the halide particals, is called irradiation. Its effect is
to limit resolution and sharpness. The thinne the emulsion
the better for sharpness but at some point the film will
become limited as to density range. Double coated films are
still made but even those have thinner coatings than in the
past. Color films by their nature must have several
coatings. Much of the technology of thin coatings now
applied to Black-and-White film comes from research into
color films.
Much of the conventional wisdom about emulsions is just
plain wrong. The idea that paper must be "silver rich" to
have dense blacks or good tonal range is myth. So are the
similar ideas about film. The performance of film or paper
has very little do to with the amount of silver in it.


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

"Dan Quinn" wrote in message
om...
At least according to conventional wisdom slow films have
thin
emulsions and fast films have thick emulsions. I know from
tests
done that a 120 roll of slow Pan F+ has much more silver
content
than an equivalent area of print paper. I do not know a
paper's
film equivalent ISO but the Pan F+ ISO is likely 6 to 10
times greater.

Mr. Knoppow has mentioned the extreme fine grain of paper
emulsions.
In itself that supports the idea of papers having thin
emulsions.
In fact IIRC, he has compared very slow micofilm emulsions
to
print paper emulsions.

I suggest that paper is slow because it has a very thin
emulsion and
little silver. I'd like to know more of the relationship
because I'm
about to do some film developer tests using print paper. I
think
the correspondence may be great thereby making for valid
tests.

I'm hoping some others will shed more light.
Dan

The conventional wisdom is wrong. Emulsion speed has
nothing to do with thickness. It is mainly a function of the
way the emulsion is made and sensitized. There are so many
factors affecting speed that its difficult to name them all
but the more important ones are the kind of silver halide
used (Silver Iodide is fastest and is usually combined with
Silver bromide in film), the exact way the halides are
injected into the gelatin, this affects the crystal shape.
The way the emulsion is ripened and how many ripenings it
gets. Also very important are trace materials added to the
emulsion. Certain metals increase speed, Gold is an
important one but cadmium and others are also used. Silver
halide is sensitive to blue and near UV light. Silver Iodide
to blue green. To sensitize the film to other colors dyes or
combinations of dyes are added. Other ingredients of the
emulsion also affect speed. These include silver sulfide and
ammonia. High speed emulsons also reqire effective anti-fog
agents and stabilizers.
Paper emulsions are made from (usually) a mixture of
Silver Chloride and Silver Bromide. Variable contrast paper
probably has some Silver iodide in it as well. The emulsions
are made differently. They are ripened less and are washed
differently. They may not contain some of the sensitizing
agents found in film.
Paper emulsion is thin because it does not have to be
thick to get sufficient density. This is because the light
must go through it twice. Film emulsion is not that thick
either. In the past many films were double coated with a
fast emulion and a slower one of different contrasts. This
extended the exposure range of the film. Modern emulsion
making technique allows equally great latitude with a single
coating. The coating can also be thinner. In a film this has
the advantage that there is less spreading out of light
within the emulsion. This spreading, due to scattering from
the halide particals, is called irradiation. Its effect is
to limit resolution and sharpness. The thinne the emulsion
the better for sharpness but at some point the film will
become limited as to density range. Double coated films are
still made but even those have thinner coatings than in the
past. Color films by their nature must have several
coatings. Much of the technology of thin coatings now
applied to Black-and-White film comes from research into
color films.
Much of the conventional wisdom about emulsions is just
plain wrong. The idea that paper must be "silver rich" to
have dense blacks or good tonal range is myth. So are the
similar ideas about film. The performance of film or paper
has very little do to with the amount of silver in it.


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

In article ,
"Richard Knoppow" wrote:

Much of the conventional wisdom about emulsions is just
plain wrong. The idea that paper must be "silver rich" to
have dense blacks or good tonal range is myth. So are the
similar ideas about film. The performance of film or paper
has very little do to with the amount of silver in it.

Matter of fact once those newer emulsions are calibrated for use,
they prove superior imop to thicker emulsions least for sharpness
of detail.

--
LF Website @ http://members.verizon.net/~gregoryblank

"To announce that there must be no criticism of the President,
or that we are to stand by the President, right or wrong,
is not only unpatriotic and servile, but is morally treasonable
to the American public."--Theodore Roosevelt, May 7, 1918

"jjs" wrote in message
...

Print developer for printing paper? May I ask why?

Silly me. I meant "Film developer for printing paper?".

In article ,
"jjs" wrote:

"jjs" wrote in message
...

Print developer for printing paper? May I ask why?

Silly me. I meant "Film developer for printing paper?".

Too much alcohol ah? Besides were you not in your own killfile,....
time to put your self back in. LOL.