FILMS

Correct storage conditions are just as important for film as for paper Incorrect conditions can lead to just as many handling problems for both types of product. This is apoint, however, which is often overlooked.

Always store film in dry and dark surroundings at arelative humidity of 50 per cent. Keep all film in one room so that its storage conditions are the same, and bring it into the same room as the contact frame at least 24-hours before It is to be used. By allowing the film to become conditioned to the new atmosphere, there will be less chance of fitting problems later on.

Do not underestimate the importance of conditioning. It takes about four hours for normal film to condition to the ambient atmosphere and about seven hours for thicker based products. Film in a heat sealed foil bag will not condition to the room atmosphere. It must be removed from the bag and left in the room environment for conditioning, Moreover, a box of 100 sheets will take longer to condition than a few sheets in a box so for quicker conditioning divide a freshly opened pack between several boxes of the correct size.

One common problem caused by not doing this, is where a set of separations is proofed and corrections are required to one or more of the films, but the subsequent remake does not fit the original film. This is most often due to a change in ambient humidity or temperature between the making of the originals and the remake. Rewashing and redrying the remake. or the remainder of the films in the set. may help overcome the problem.

Sheeting roll film will let air reach the material's surface more easily and is therefore a more effective way of conditioning than if it is left on the roll.  Properly stored film will last along time, but it does have a shelf-life, so check the expiry date. When taking a sheet of film out of the box, be careful not to drag it quickly across the surface of the sheet below as this can cause static Always handle film carefully. picking it up by its corners.  If you want to clean film, use only a cleaner designed for the job. Sprays which have anti-static properties are available and these can be used on equipment in conjunction with anti-static cloths. Sprays should not be used on unexposed film.

Films can vary in the matt or gloss surface. A matt material requires a shorter vacuum time because the air will escape more easily during drawdown. If you're going to produce a job which has very fine tolerances, use material with a thicker base, since this will give it more dimensional stability. Large sheets are also easierto handle if they are thicker.

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