Resist the urge to alter lamps, etc. Quartz and halide lamps
often have reflectors which vary in size and design; be assured
that the manufacturer knows best how these should be mounted
and do not think you can improve the situation by changing
them. With lights designed for good coverage at a specific
height, moving them higher or lower is not agood idea.
Make sure that the vacuum holes are not obstructed and
drawdown slowly. It may take a full minute or more to achieve
good vacuum drawdown depending on the type of frame and size of
original. On some frames it is possible to see Newton Rings
forming during evacuation. When these stop forming, you should
wait at least another ten seconds before exposing the film.
Always keep the contact frame clean Use a glass cleaner
designed for this purpose; some cleaners leave deposits on the
glass. Dust is a common source of trouble when contacting. For
this reason, it is better not to have a carpet on the floor and
to site the equipment away from windows or extractor fans.
Operators should avoid wearing clothing which causes static,
such as man-made fibres.
One source of contamination which is often overlooked in
hard water areas is the use of some types of humidifiers. These
can cause afine precipitation of hard water particles to
collect on surrounding surfaces which can cause problems with
optics and with materials. However, humidifiers do offer a
convenient means of maintaining relative humidity. Working at
arelative humidity between 45-55 per cent is recommended.
Use the chemicals at the recommended
temperature; this does vary between makes but is
generally around 35 deg C. Development time is normally between
20 and 30 seconds but if the chemical temperature rises, the
development time will need to be reduced. The chemicals used in
the processor must be at the correct concentration. For every
one square foot of film developed, about 45 ml of developer
will be exhausted. Some chemicals are not compatible some and
this may cause problems, for instance, high D-Min (minimum
density) on films.
If you do not fix, wash and develop properly you will affect
their storage-life. When washing with water, aim for aflow rate
of at least two litres a minute. Water temperature also affects
washing efficiency and wash temperatures below 15 deg Cshould