photographic processes
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silver
gelatin - Also
called black and white, this is considered to be "traditional"
photography. This process uses commercially-produced paper that
is coated with a silver gelatin emulsion. Prints are most often
made by enlarging a negative onto the paper. The latent image
is then developed in a series of chemical baths to produce the
final photograph. Black and white prints may be toned, bleached
or hand colored using a variety of media. Given proper handling
and processing, black and white photographs can be archival.
cyanotype
- One of the oldest photographic processes, cyanotype
is an iron-based process which requires direct printing. The
emulsion is mixed from the raw chemicals and coated by hand
onto the support media. The negative is placed in direct contact
with the emulsion and exposed to a strong UV light source. After
processing and drying, the final photograph may be hand colored
using a variety of media. Given proper handling and processing,
cyanotypes can exceed a comparable black and white photograph's
archival qualities. Unfortunately, toning or combining cyanotype
with other processes may decrease the lifespan of a print.
van
dyke brown - An historic process, van dyke brown is
a combination of silver and iron. The emulsion is mixed from
the raw chemicals and coated by hand onto the support media.
The negative is then placed in direct contact with the emulsion
and exposed to a strong UV light source. Because of the combination
of metals used, van dyke brown prints can become unstable if
not handled properly.
gum
dichromate - Gum dichromate uses a chrome salt mixed with
watercolor pigments and a natural gum. After mixing, the emulsion
is hand coated onto the support media. The negative is placed
in direct contact with the emulsion and exposed to a strong UV
light source. Gum prints can be re-coated and exposed multiple
times for a variety of effects. After processing and drying, gum
prints may be hand colored using a variety of media. Gum prints
should be handled with care to enhance their longevity.
salt
- Invented by William Henry Fox Talbot, salt printing
involves soaking a paper in a salt water solution, allowing it
to dry, then coating the surface with silver nitrate to make a
light-sensitive surface. After drying a second time, the negative
is placed in direct contact with the emulsion and exposed to a
strong UV light source, then processed in a series of chemical
baths to remove the excess silver and permanently fix the image.
Salt prints can vary in tonality depending on the type of salt
used and a number of different metal toning baths. Salt prints
should be handled and displayed with care due to the delicate
nature of the print surface.
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