Cleaning 35mm slides

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    • #132666

      Hi all,

      We have a few small collections of 35mm slides that need to be cleaned/ dusted and rehoused. We’re anticipating some summer volunteers, and I was hoping I could make this a project for one of them. If only I knew how to do it myself!

      The slides have a range of dates from 1965 to 1991. A good deal are  labeled Ektachrome and Kodachrome, but many are  blank or labelled simply color transparency, color slide, or color film. The Kodachrome and Ektachromes also vary between the terms transparency, slide, and film. Is there a difference? Should one labelled as film be treated differently than one labelled transparency? Should the Kodachromes and Ektachromes be separated?

      As for the mounts, they are primarily of the cardboard variety. Sould be worried about these? What about the plastic mounted slides that seem to date from 1988 onwards?

      In terms of cleaning should they simply be dusted? Some of the Ektachromes from 1965 look like they might have mold? Is PEC-12 safe to use?

      And finally one last question about storage. Would it be better to purchase an archival box system, or can we use the polypropelene pages that hold 20 slides each?

      Sorry for all the questions. I just want to make sure we get it right the first time and spend our money wisely.


    • #132673

      gelatin based film shouldn’t be cleaned with no water included solution if possible.

      Actually I don’t think that liquid based cleaning should be performed at any film except you can be sure the external gelatin layer is in really good shape, and for that its necessary to have a well trained eye in the subject.

      Fungii presence is one of the reasons that can justify the use of liquid based cleaning methods, but in the other hand fungii and direct contact water damage are the causes of gelatin weakness that can produce, when cleaning with solutions, the loss of the binder and so the loss of the image. Advanced fungus deterioration of water damage will leave the gelatin layer in really bad shape and the mechanical action of cleaning can be the loss of it, if you also do it with a wet cotton, you can imagine…

      Sometimes the fungii we see in old film is only the traces of inactive one produced a lot of years ago. Sometimes is removable, sometimes not, but the use of solvents of any kind can also leave traces in the binder, and some of them are really dangerous and must be used with mask, protection glasses and air extraction devices.


      So I think that my opinion is like “if you are not really well trained in evaluation damage and integrity and you cannot hire a trained conservator to do it, try to keep the liquid based treatments far from your films” even if the use of cleaners are really extended in the States and a lot of people found it really normal and safe. Gelatin can pass from “perfect shape” to “very weak” really fast and without not too many signals, and you will notify in the works of ways.

    • #132672

      speaking of mounts, if you can provide proper housing, you may want to retire them in order to your slides will be in direct touch with a material you really know what it contains. Plastic mounts can have PVC, and the cardboard ones will be a souce of acidity.  In the other hand, they assure that the image surface will never be in touch with the enclosure.

    • #132671

      Thanks Mauro. I’m glad I asked about the PEC-12; all the suppliers make it seem like it is such a great, safe product but I agree with you about being cautious. We’ll stick to dust mitigation. Would you recommend using a small blower bulb, or is there some type of dry cloth wipe we can use?

      I’ll take a closer look at some of the slides that appear to have mildew. I believe it is all inactive, but if they really need to be cleaned  I’ll make sure that they are taken to a professional.

    • #132670

      In order to respect the concept of going from the soften option to the harder one and also to maintain the abrassion to the minimum, we use to apply a soft air blow at first and only after a special soft brush that will remove the dust the air blow didn’t do.

      I cannot think of any cloth now but am sure there’s something somebody tried and may work, but we enter there in the terrain of things we must do only when we sure gelatin is in good enough shape to resist it.

    • #132669

      Thank you so much!

    • #132668
      Lou Morgan

      On this part of your question: “the terms transparency, slide, and film. Is there a difference?”

      I am a user of slides and film images not a conservator but I can share the meanings of the terms. All 3 are used fairly interchangeably but there are differences:

      Film is the broadest term in photography. It is anything that is not a print/paper. It is a transparent material usually with emulsion on it depicting an image. Can be a negative or positive image. Can be large or small. ” He was shooting on 5×7 film in his studio camera” “There is unexposed film in her camera”

      A transparency is most always an original, positive image like a slide. But I have had commercial photographers shoot studio work on 4 x 5 inch transparencies for high quality photography for reproduction. So a transparencies can be many different sizes and usually without frames.

      A slide is usually 35 mm positive film mounted in a frame that can be run easily through a projector – therefore it name. There are larger and smaller format slides, but the most common is 35mm and they should be labeled as such.

      So, a slide is made of film but so are negatives. There are many different formats of transparencies. 35 mm slides are the most common consumer format.

    • #132667

      Thanks Lou. I was asking because although everything that I was looking at were in fact 35mm slides, they had been labelled by Kodak, the local photo store, etc. using varying terms. (for example Ektachrome film vs Ektachrome transparency, or sometimes just the generic “color transparency.”)  I just wanted to make sure that we could treat the transparencies like we would treat film.  In the case where they are labelled transparency, could that suggest that these are copies and not the original film? Or is it just a case of semantics?

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