Mendel Leisk , Sep 19, 2009; 11:33 a.m.
If you scanner has ICE (infrared detection of of defects) I would try scanning them first. Start with the least important slide, scan, attempt your cleaning method, then scan again. You do not want to plunge into a cleaning method that might leave them worse than at the outset. In my experience the best approach was just scanning them as-is and relying on ICE, coupled with manual touch-up within Photoshop. I tried cleaning one (unimportant) slide by simply washing in a bath of distilled water with a drop of Photo-Flo. The result was a disastrous increase in stuff. You might have better results with something like Eclipse Fluid on PEC Pads, but again, tread cautiously. The last thing you want to do is zealously clean them all, before starting scanning.