"Tuning" CD's

I used Allstop (?)… the yellow edge marker on all CDs. It seemed to improve the sound a bit on my earlier CD players. I experimented a fair amount 25 years ago to verify. There was a little lathe to cut the sides. All, intending, I believe to stop internal light reflections from the exterior edges. 
 

I had treated all my CDs. But I don’t listen to CDs any more.

I still have CDs where I painted the edge with a special, audiophile-marketed green marker. Did it help? Maybe when I played them on my first CD player, a player that went belly-up maybe three days out of warranty.  I can't recall the player's brand name. In any event, I haven't painted a CD edge since.

Then this has been a thing for quite some time! I had no idea there were markers made for the task.

The point of first sanding the edge is to ensure that the edge is matte black - not gloss black which would just create a black mirror. What I noticed immediately is that treble glare was reduced most noticeably on piano and higher pitched wind instruments. There was also a widening of sound stage and better separation with longer decay. I have a fairly resolving system.

Were the pens you used actually matte? Looking on Amazon I found one marker advertised as "matte," but the reviews said it was actually gloss.

I don't see anything odd about this idea. It is not a violation of the sacrosanct rebuttal that "it's always and only ones and zeroes." The theory in play here is that the transmission of data is being smeared.

Thanks for your replies.

Ok, I should have researched this topic first: