Alternative Processes
Cyanotype. The
Cyanotype process was invented by Sir John Herschel in 1842. It is perhaps
best known for its use for the production of architects blueprints before the
invention of the photocopier. The process is very simple producing high contrast
dramatic results. With care large finely details prints can be produced. The
most used formula are of two bath formulation. However a single, solution developed
by Dr. Mike Ware (web site on alternative processes http://www.mikeware.demon.co.uk/conspec.html)works
well if you can obtain the chemicals (chemicals and kits can be obtained from
silverprint http://www.silverprint.co.uk).
Formula
Solution A
Ferric Ammonium Citrate(ammonium Iron III citrate) 20g in 100ml distilled water.
Solution B
Potassium ferricyanide(potassium hexacyanoferrate III) 10g in 100ml water
Make up carefully in cold water. Store in dark brown bottles and keep in
the dark. Mix 1+1 just before use.
Treat all chemicals as toxic. Although these solution are not particularly,
dangerous many photographic chemicals are very toxic and have cumulative effects.
Take particular care when mixing powders as these can irritate and damage the
lungs. Always read the instructions and take note of hazards. However
cyanotype does leave deep blue stains everywhere! Wear gloves.
However if you only wish to try the process out or make a small
number of prints then buying a kit is probably a better option. Careful consideration
needs to be given to the subject matter. Try strong subjects with limited
tonal range. Colder type subjects may make better subject matter than warmer
intimate portraits for example.
The process.
The first problem to overcome is finding a suitable negative. Since the negative
needs to be contact printed with a an ultra-violet light source, the negative
needs to be the same size as the print. Access to 10x8 or 5x4 inch negatives
is ideal. If not negatives can be made using a photocopier on to special acetate
sheets or scanned into a computer and printed onto suitable acetate sheets.
Paper.
Any type of paper can be used for your first experiments if you wish, but
good quality paper will last longer. Watercolour paper can be used for the
best results.Take care to consider the influence of texture on the desired
result. Tape the paper down by the corners under safelight conditions or subdued
tungsten lighting. Coat the paper carefully by using a wide flat brush 1/2
inch or 1 inch. Make two passes -top to bottom across the page then left to
right. Aim for a very even coating without puddles. For best results use a
brush without a metal ferule to avoid contamination. You can also try soaking
in a tray and hanging up to dry if you have a good quantity of solution.
Exposure.
This require an ultra violet light source. A lamp is best for consistency.
Failing that, the sun can be used or a sun bed. Remember that UV sources can
damage skin and eyes-be careful! An improvised frame to hold the negative onto
the paper in a fixed position with a sheet of glass for flatness (clean but
thin tape the edges) will allow for examination of the image without movement.
Make test strips in the normal way. Make strips 2,4,8,16..minutes and refine
time as you go. Expose until the print looks overexposed as the density is
much reduced during washing.
Development.
Not development as photographers know it, more a process of fixation. The
paper is soaked in water to remove the areas unaffected by ultraviolet light.
Wash gently for 5-10 minutes or until the yellow stain disappears and hang
up to dry. The colour darkens as the paper drys.
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