THE PROTECTION AND STORAGE OF TRANSPARENCIES

Part One. Mounting and protection of slide material.

By Ron Croad

For many years there was only one way to mount slides and that was between glass. It was a tedious job as each slide had two nieces of glass which had to be clean and free of dust, a mount of folded paper, and four lengths of gummed paper three black and one white for the title the slide was mounted in a jig, arid ones mouth became very tainted with gum after a session of slide finishing There are still people who mount slides this way~ but I suspect that there are few and far between. The system has two snags, one is condensation which forms on the glass, degrading the image of the slide,. and the other is the risk of breaking of the glass destroying you. masterpiece. The big advantage is that it is the only way in which a slide is absolutely held flat, Gepé make plastic mounts that have glass with an etched surface which cuts down on condensation and also prevents a phenomenon known as Newton rings ( Rainbow like circles) forming It goes without saying that the glass mounts of that pattern are quite expensive.

At the opposite end of the scale are the card mounts which are supplied with some of the trade processed lm, This type told the film fairly flat, and it is easy to write your title on them. When they are in your projector then their weakness shows up, as they often ‘pop’. This of course is another word for bending, and. it means that you have to refocus the projector before you get a sharp image. Card mounts are cheap, self adhesive, and easy to use, but have limitations in the long term, as they are not reusable, and tend to bend after a while. They have one other snag if used in auto slide projectors, the slide mechanism sometimes fails to pick up the slide, as it is very thin. 

Somewhere in the middle range of pricing comes plastic mounts.. The quality of these varies according to price The ones in the form of a book cover were popular, these clicked together with press studs, or were meant to. I’ve heard a lot of complaints about these but had no trouble myself. Mind you I had on a lot of occasions to hit them very hard with the mounting press. The secret lies in trimming the film very~ accurately, so that none of the end overlaps the small pop fasteners.

Another type of plastic mount is made in the form of an envelope which has an open end. The. transparency is mounted in an Inexpensive jig that hold the mount open so that ..the. film can be slid in place.

The most expensive of the plastic glassless mounts is the Gepe This type is very accurate, and can be mounted in a special press, which makes the job of mounting very easy.

When choosing your mounting system it is very important to try a few mounts for accuracy. try looking along the slide with it held flat. If the slide is not held reasonably flat all round then you will not get the best out of it in your projector. The center and edge will be on different planes one or other will be out of focus.

When cutting your slides for mounting, it is worth investing in a film cutter. These cut your film at exactly the right length and also keep the ends square, there are also no problems with finger marks.

To complete your mounted slide it is usual to add a title and to spot it Titles on card mounts can be written with normal writing instruments, but the plastic mounts cause more of a problem The best thing that I have come across is the type of fine pen sold for use on overhead projector film. They are available in graphic Art Shops, In use they etch into the plastic and will not rub off when rubbed with the fingers.

It is best when you start up a slide collection to standardise on one type of mount as different thicknesses of mount can cause problems to both standard and auto projectors Either you or the projector are continually re—focusing. This final advice is not as straight forward as it sounds as certain types of mount have been withdrawn, or a new type stocked in several cases That can be most annoying if you already have several thousand slides in a favourite mount.

Choose a mount that holds your transparency flat, and stick to it is the best advice I can give.

Ron Croad.