I think Cavey you might be blending 2 things here. Nino brought up dimpling due to thin clear coats and stated noticeable dimpling has been noted on games and you introduced damage and wear to clear coats which is a different issue and believe that suggests wearing down or cracking of the clear down to the screen layer of the playfield. Admittedly the clear coats have been holding up well on most games from observation of the various forums but the dimple depressions has been around for years and maybe on the increase of late and guessing that clear coats have evolved over the years improving wear and improving the degrees of resistance to dimpling.
Just a theory...
I am not an expert in clear coats but brought up on timberwork with my father being a woodwork teacher for 40 years + 15 years into his retirement and having written a couple hundred articles for various mags around the world so learnt a bit through his knowledge. A steel ball is harder than timber which we all know and I am sure all clear coats as well. My theory is that the ply used - meaning soft or hard varieities and the number of layers of ply plays a big part in what dimples develop I believe. When I got my IM late 2010 I asked AMD if they could get me a spare IM playfield which they did and interestingly for $650 to AMD's door. The first thing I noticed while both playfields remained the same thickness was the number of layers reduced with each layer becoming thicker which in turn allows more top layer compression and would be cheaper to make. Also Canadian Maple can be found as a soft or hard variety and the soft is commonly related to fast growth plantation timber which is cheaper. I don't know for a fact but the problem could be a combination of number of layers, soft or hard variety used and possibly a middle of the line thin clear coat used which will wears fine as the clear is strong but not strong enough to resist a steel ball racing around causing compression spots = dimples. Could Stern be doing a thicker clear to compensate for cheaper slightly softer ply with less layers? They won't admit to that.
The fact is dimpling has been around for a while and you often need the right light to see them and maybe on the flip side once all the playfield is dimpled it is harder and flat again so keep playing and enjoy.
