Small black specks on colour slide

[Stephen_A]

Hi,
I just scanned some Kodachrome slides on a Nikon Coolscan. The slides are twenty years old. Before scanning, I cleaned the slides carefully by hand in water, using a tiny bit of detergent. A professional photographer recommended this. It usually works. Some of the slides still have small black specks on them. You can see them on this if you magnify it.

It's not a big deal, but I was wondering if anyone could confirm whether these are permanent damage to the surface of the film or merely the result of insufficient cleaning.

Thanks very much in advance for your comments.

http://www.mediafire.com/i/?vcd57raaqq5erq5

[Flashtones]

that's a lot of specks. how dirty were these slides to begin with? what were the storage conditions? is it mold?

[Stephen_A]

Not especially visibly dirty - most of it was invisible to the naked eye. They were stored in normal plastic slide pocket sheets, but in ring files. Dust got in, and there might have been mould. Normal conditions here in Hong Kong where eight months of the year are pretty muggy and hot.

[Flashtones]

I don't have a lot of experience scanning old slides so I can't be of much help, but that just doesn't look like dust to me (too regular in size and distribution). Certainly not if you've washed them. I wonder if it's a sort of reticulation from processing? Are all the rolls like this?

[Stephen_A]

The spots appear on some frames of all the rolls I've done. As far as I can recall, they were all done by the same processor.

[mistermonday]

Stephen, Examine with a 10 x magnifying glass 1 slide that you have not washed and determine if those specs are actually there. If they are, trying cleaning the slide with 99% Isopropyl Alchohol (you can use 90% but no less). 99 is regularly available at all pharmacies. I would never recommend using setergent on the emulsion and if you use water it should be distilled.
The spots do not look like any moould I have ever seen on slides. Usually mould is found in clusters and not as very tiny dots with that type of distribution. The slides may have been exposed to some atmospheric chemical(s) that could have attacked the emulsion. See what happens when you clean one with the Iso.
If the Iso is successful removing the spots, you can get a small spray bottle with a fine mist and a microfiber cloth (sold by opticiens / optical dispensers / photography supply stores). Spray one squirt on the cloth and wipe to clean the slide.
Regards, Murray

[Stephen_A]

Thanks Murray and Flashtones for your replies. Murray, the spots are on the unwashed slides. Thanks for the info regarding the isopropyl alcohol and cloths. Carefully noted.

Stephen.

[mistermonday]

Stephen, please let us know how it turns out.
Regards, Murray

[Stephen_A]

I will Murray. The only problem is a lack of 90-99% isopropyl alcohol in pharmacies in Hong Kong. 75% is the highest isopropy. The closest I can find is 95% ethyl. Will that do?

[mistermonday]

Stephen, isopropyl is actually a denatured form of ethyl alcohol. You can use it BUT note that Ethyl alcohol is also used for consumption by humans in alcoholic drinks, So just make sure it does not have additives in it (like perfumes and flavors). I would assume if it is sold at a pharmacy it is probably ok.
Regards, Murray

[lurch]

Murray, isopropyl alcohol is NOT a denatured form of ethyl alcohol, and it is NOT consumed by humans, period. The two are different chemicals - related, but different. What you get from the drugstore is isopropyl alcohol, also known as rubbing alcohol. The percentage indicates how much water has been added to dilute it. I don't know about Hong Kong, but if the pharmacies there have 95% ethanol, it is likely to be denatured (often with benzene) and is NOT drinkable. Also not a substitute for isopropanol.

[mistermonday]

Lurch, I did not say that Iso is consumed by humans, it is not. But pure ethanol is the kind that is used in many Alcoholic beverages produced for human consumption. For purposes of cleaning, Ethanol is often substituted for Iso, depending on what it has been denatured with.
Rubbing alcohol, most commonly found in pharmacies, and so labeled, is usually around 70% iso and is not suitable for cleaning film and lenses. I don't know why pharmacies in HK do not stock high grade iso. Perhaps they consider Ethanol a perfect substitute for cleaning and disinfecting purposes.
Regards, Murray

[Stephen_A]

Hi Murray, Lurch and Flashtones,
Sorry for being so long in getting back. I had a computer meltdown that took me a week to sort out. (Might I take a moment here to strongly discourage anyone from using Mozy online backup as they managed to scramble a lot of my data and if not for another backup I'd made I'd have been screwed).

Got the 99% isopropyl. I don't know what happened. I think I caught a pharmacy assistant on a bad day. I tried cleaning the slide with it, and the specks remain. They're obviously somehow become ingrained, and I'm going to leave it at that.

Thanks to everyone for taking the time to put in your knowledgeable and thoughtful input.

Stephen.