Information for education.
Re clear coating over existing FACTORY clear coated playfields can be detrimental, and wasteful in money.
If improperly prepped, in the long term there can be separation of the clear coat layers, especially if different formulas were used (solvent versus water based, automotive grade versus rattle can), leading to ghosting, insert microcracks, and chipping.
Even yellowing can result, but this is rare. It only applied if not done properly in a spray booth and drying rooms, and chemicals are improperly mixed for bonding.
There is no absolute guarantee this is a perfect solution to playfield protection, dependent on environment conditions.
This whole concept was a generated by new owner/collector fallacy to achieve the "quest for the ultimate shiny playfield".
This is not considering any type of factory imperfections, which is a completely valid reason to clear coat to correct deficiencies in either priming, ink screening, or coatings (tuffcoat, lacquers, or clears).
This fad started in the early 2000s in response to valid requirements to fix EXISTING games with WORN PFs, and people started taking the concept to the extreme with some HER games.
It caught on and many people personally started doing it on there own improperly.
It was reinforced in the late 2000s by Stern's decision in 2010 to start thickening clear coats for the "shiny factory" at the request of owners. Now, dimples are most noticeable initially due this this clear coat change, materials, application, timing, curing, and some variations on wood hardness.
There is absolutely NO reason to reclear coat a NOS playfield.
Just keep the original highly waxed, clean, and maintain their games, and the game outlive the owner.
Many times people think I had recleared a playfield on many of my games but they were simply clean and waxed.
If an owner is really concerned, install a playfield protector overlay, but recognize this will not stop things such as dimpling.
The example below is Dixieland (Bally, 1968) from my collection with an original Bally "tuffcoated" playfield with used lacquer, not clear, but is nearly 50 years old! It was simply well cared for as a game.
Dixieland PF FINAL Master.jpg