Cleaning Slides before Scanning

I recently cleaned about 90 old slides of dust and dirt. The techniques I settled on are illustrated here, but I don't claim they are the best. I will probably be scanning another batch soon, and the next time I may use something different !

Equipment

A regular desklamp is essential. I like the black color because the black base provides a good background for inspecting the slide. For more on this, please see the procedure below.

Distilled water in a bottle with an eye-dropper. I also bought a bottle of PEC-12 Photographic Emulsion Cleaner, which I hoped would remove mildew. It *did* remove the mildew from the base (shiny) side, but distilled water worked too. I have not found anything that removes mildew from the emulsion (dull) side; I think the mildew grows inside the emulsion. I am keeping the PEC-12, but still waiting to find a substance that it removes and that water cannot remove. Two substances listed on the PEC-12 bottle are tape adhesive and oil.

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The PEC-PADs came packaged with the PEC-12. But I found them awkward and wasteful to use. I found a Q-tip easy to use, but the cotton fibers tended to come off. So I got foam swabs at an electronic store, cut a PEC-PAD into strips, wrapped a strip around the swab, and fastened it with a paper clip. I think a Q-tip would work just as well as the foam swab, but haven't tried it.

or

I tried a vacuum cleaner, but mine wasn't strong enough to get the stubborn dust particles. I had better results with the can of compressed gas, but I used up a whole can in no time. Mark had the idea of using his scuba tank with an Air Blowdown Tool. I took the red plastic tube from the compressed gas can, and plugged it into the tool. Cleaning 90 slides took about 2/3 of the tank. Thanks Mark!

Procedure

• I hold the slide under the desklamp at a very low angle to the light, so the dust, dirt and mildew appear white. I position the slide in front of the black base of the desklamp, so the surface of the slide appears perfectly black.
• I blow the slide with compressed air to remove the dust - stubborn particles get a strong direct blast.
• If the air does not loosen all the particles (the usual case), or if there is dirt or mildew on the slide, then I put a drop of distilled water on the slide and wipe it with the swab on a stick. Then I blow-dry the slide again. On the base side, the water beads up nicely and blows off quickly. The emulsion side is wetted more by the water, and takes longer to dry. Usually a tiny drop collects in the corner and I have to blow it around the edge until it evaporates.
• When the slide is dry, I check it once more for stubborn dust particles. I often find that the mildew no longer appears white, but is still visible as small raised "blisters" on the emulsion side.
• After a roll of slides, the PEC-PAD strip often acquires a yellowish tint, so I replace it. I don't know whether the yellow is dirt or a chemical from the slide itself.