Even with these
precautions I can see significant amounts of dust when the scan is greatly
magnified. I've come to the conclusion that almost all of it embedded in the
emulsion and results from sloppy processing labs with no filtering of their
solutions. Some labs give MUCH better results than others from the
cleanliness standpoint as well other areas.
I've also noticed that there are two types of dust. The first type is made up of rather large pieces and is easy to brush off a slide or negative. The other type is much much smaller and does indeed seem to be embedded in the emulsion and doesn't brush off. The first type isn't a problem, is easy to remove, and doesn't require ICE if you take care of your slides and negatives.
The second type is very rare (for me) and I don't know if ICE would help remove it or not (I don't use ICE). If it is indeed made of dirt particles because of poor filtration by the lab, then ICE might help remove it. If, instead, the "dirt" is really chemical compounds or small partially dissolved pieces of emulsion, then ICE probably wouldn't help as infrared light would pass through it as easy as the film itself. If anyone with ICE notices this type of "dirt," you might report to us if ICE is of any use. This is all really quite irrelevant because no lab should embed any kind of dirt in the emulsion. If you see it, tell you lab about it and insist that they do something about it. If not, find another lab. In the meantime, I've never found a real need for ICE and have only had one "contaminated" slide that required any tedious clone tool use to remove the zillions of invisible (to the naked eye) "dirt" particles.
