[pure-silver] Re: Calibrating a colour enlarger to ISO paper grades wrt Way Beyond Monochrome
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Fri, 11 Dec 2009 17:53:35 -0800
----- Original Message -----
From: "Tom Kershaw" <tom@xxxxxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Friday, December 11, 2009 5:10 PM
Subject: [pure-silver] Re: Calibrating a colour enlarger to
ISO paper grades wrt Way Beyond Monochrome
A brief note about the Ilford primer on paper. In this
PDF its stated that Silver Chloride emulsions are warm toned
and Silver Bromide emulsions are cold toned. This is not
quite the case. Chloride emulsions tend to be finer grained
than bromide, as a very broad rule of thumb fine grain
silver is yellower than coarse grain silver, to the point
where the yellow filter in Kodachrome is made of extremely
fine grain silver called colloidal silver. However, the
emulsion color in paper is also a matter of the manner in
which the emulsion is made and possibly additions besides
the silver halide. Note that Kodak Azo, which was a chloride
emulsion, was neutral toned and Kodak Velox, also a chloride
emulsion, was blue-black. OTOH, Kodak Athena, a very slow
chloride contact paper is almost brown-black with a suitable
developer. Pure bromide emulsions do tend to be neutral or
cold tone. Agfa Brovira is an example. Most Kodak papers,
both contact and enlarging were mixtures of bromide and
chloride, one can get just about any image color from the
combination.
--
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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