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.

PROCESSOR

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 be avoided.

<< Previous    1  2  [3]  4    Next >>