I've found this discussion interesting on a couple of levels.--- On Tue, 10/2/12, Art Shifrin <[log in to unmask]> wrote:
<>snipI was then with Ampex and enjoyed a special friendship with ‘Willie’
Willumstadt (sp?) of The Sound Shop here in NYC.  In one of our many
conversations I told him about the device and method.  His response was one
of no surprise, including wondering why no one in the business had thought
of it before (unless deliberately kept as a trade secret).  It was
comparable to what audio perfectionists in the ‘film biz’ (yes, there were
some) had been doing to optical tracks for years: painting out transient
noise with black ink on positives: thusly NOT requiring physical cuts of
the media.  I don’t recall if I ever asked if the procedure had better or
same results on variable-density versus variable area versus push-pull.<>snip
Since I only worked with variable-area, I can't say for sure, but I think it would be the same for variable-density, since you are, in essence, fading out the light source.

This process of using black ink to cover a cut in an optical track was called "blooping" when I worked at ABC television in Hollywood.  ABC was called "the film network" in the industry at that time (the 50's), since it was one of the first that had contracts with the film studios, especially Disney to air their series.  The Lawrence Welk Show was the exception being shot at the ABC Hollywood studio, and aired on black and white film through a "quick kine" process.  

When we would re-edit the original studio film series shows for summer rerun,  we would have to change the time format to fit the new integrated commercials, again all on film.  So, we would have to make "lifts" of sections of the show.  It was tricky, since the 35MM sound track leads the picture by 20 frames, so in making the picture "chop", we would be cutting into active modulation.  The editors doing this would have to plan carefully where and how to make these cuts, and when they had done the surgery, I as an assistant would bloop the sound track to make a tapering fade using a aluminum jig and a spray gun in a booth set up specially for the job.  So, that was another of those ways invented to deal with audio as the problems "popped" up.
My other comment is about what I learned about "de-popping" when I first worked on my two DAWs at Family Theater in Hollywood re-mastering their radio broadcasts from 40's and 50's transcription disks.  At that time, Cool Edit was thought to be the best software around to do the job of cleaning up audio from analog sources, so since I'd dealt with soundtrack audio problems as a film editor, I found it a fairly easy transition.  I loved the new way to solve these problems, but there was of course a learning curve.  I gradually found new ways to fix things such as using the better side of the groove for the least worn and best audio.  As far as pop elimination, Cool Edit has (I still use my customized version for my jobs) in its "noise reduction" section, a "clip/pop eliminator" which works on each visual spike in the waveform as I bracket it with my trackball by holding down my left button as wipe/select it, and it becomes highlighted on the waveform.
  So, this works well on most pops, but there are some pops with heavier transients that have a low end component. When I find that, I use a tailored FFT low end filter on the selected section to finish the job.  I'm still amazed after all these years what magic tools I'm able to use to make it all sound perfect on my earphones (my major final double check).  It's very satisfying, and thank God, I can still hear the difference and so can my customers.  As you all have said, it can be a time consuming process, but the results and satisfaction is worth it.
Rod Stephens