One my binders of 35mm slides.

In my younger days, I shot 35mm film and slides, and I still have the majority of those today. I have been slowly but surely digitally scanning them. Fortunately, I stored them properly so my digital copies require very little touch-up work.

Digitally scanning negatives, slides, and prints is a lot like painting a car or the interior of a house. You get better results if you take the time to do the necessary preparation work. This is especially true when it comes to properly cleaning a slide or negative. When scanning a tiny slide, and generating a 600% enlargement of it, every dust particle, scratch, piece of lint, and hair will be huge in the scanned image.

When I started digitally scanning, I found many websites on how to correct color, digitally remove dust specks, and fix cracks — but there was little information on how to properly clean before you scan.

In the post, I will describe the technique and tools I used to restore a slide. Recently, I was helping my friend Zak move out of his house, and we found some slides sitting on a shelf in the basement. They were dirty and greasy, and we weren’t sure what was on them.

Zak’s grandfather was a retired U.S. Marine Corps Warrant Officer who traveled from base to base in the late 1940’s and early 1950’s. The best we can determine is that he took this slide in Hawaii during this time frame. Was there hope for this 60-year-old slide? Sure!

First and foremost, when it comes to slides, keep moisture away from them! Water will ruin them! So, keep your beer or iced tea away while you are working on this. You need a clean dry area.

The slide was a Kodak Kodachrome, which was introduced in 1935, and was discontinued in 2009. Fortunately for us, Kodachrome is appreciated by the archival and professional market for its dark-storage longevity. When scanning it, you should know that since Kodachrome is generally used for direct projection using bright white light — it possesses a relatively high contrast.

It should also be noted that scanning Kodachrome slides can be problematic because of their tendency to produce a blue color cast. This is because many scanners use an infrared channel to detect defects — the long wave infrared radiation passes through the slide but not through dust particles. Kodachrome’s interaction with the infrared channel can cause a slight loss of sharpness, and the absorption of the cyan dye extends into the near infrared region, making this layer opaque.

If your scanner software has a check box to optimize for Kodachrome,  use it.  Also, when processing the photo, take in account for blue cast.

Okay, now let’s get busy. First of all, use compressed air to clean your entire work area to include the slide and the scanner. If the slide is really nasty, remove it from the its holder by cutting it open very, very carefully along the edges, then peel open the cardboard (or plastic) frame.  Brush all of the cardboard (or plastic) cuttings away to keep your area clean. Pick the slide up by the edge with the holes, and use the loupe to examine the slide. Identify any particularly nasty areas which might need special attention. Once it is cleaned, place the slide on a new PEC pad.

Set the slide down on the new PEC pad, and place one drop of Photographic Emulsion Cleaner (PEC-12) on another PEC pad. Don’t use alcohol pads, or some other homemade concoction — just spend a few dollars and get a bottle of PEC-12. Why ruin this precious artifact because you got cheap and lazy? This stuff will work on negatives, slides, and will even remove ink pen from a print.

With one finger press the slide flat on the table (on the PEC pad), and clean it with the PEC pad with the fluid on it. Be careful not to catch the edge of the slide causing it to buckle. If the slide is old, you could create tiny crack lines, or worse, if it is brittle, you could break it. So, just take your time! Pick the slide up by the edge again, and flip the pad the slide is resting on over. Finally, get a fresh PEC pad with another drop of cleaning fluid, and clean the other side.

Use the PEC fluid sparingly. I repeat, use the PEC fluid sparingly.

Make sure the scanner is free of dust and the scanner’s glass is clean. Put on a fresh white glove, and place the slide in the scanner. Keep the glove on whenever handling the slide, or whenever you are near the scanner’s glass. Fingerprints will distort your final image.

Lastly, scan your image and place your cleaned slide in a proper archival sleeve.

As my Dad always said, “the right tools for the right job.” You’ll need PEC pads, razor blade, loupe, bottle of PEC-12, white gloves, compressed air, and of course a digital scanner capable of processing transparent materials.

Use sharp tool, carefully remove the slide from its cardboard frame. This step isn’t always necessary but if the slide is really nasty, why just push the grime against the edges of the frame?

I then placed the slide in the Transparent Materials Adapter (TMA) of my HP ScanJet 4010 using white gloves. If the slide is curved, try to get it is flat as possible, or consider remounting in a new frame. A curved slide will result in a distorted image.

The left image was scanned without being cleaned or Kodachrome optimization (note the blue cast). The middle image is a cleaned slide with Kodachrome optimization. The right image has been corrected in Photoshop using various techniques.

The final image — not bad for a greasy 60 year old slide found on a basement shelf.