Quoted from sawbill:Regarding clear PF protectors, so far I'm not a big fan. I put one on my Black Knight several months ago, and it is actually rubbing off the key lines to bare wood around the round inserts going up the middle of the PF. Wood dust is accumulating above the concaved inserts. I think the protector shifts around very slightly and rubs against the PF, especially affecting vulnerable areas around inserts. I also think that in general debris just collects under the protector. At some point in the not to distant future I'm going to pull off that protector, clean and re-wax, and eventually clear coat the BK.
I can't speak to a play field protector rubbing off key lines as I have not had that experience with my protectors.
Regarding wood dust accumulating above the concave inserts, I had junk and dust accumulate underneath my protector until I finally got it all vaccumed out. It is kind of like sweeping and mopping a kitchen floor. You can sweep and mop and then sweep again and still sweep up all kinds of small trash. It took me 3 or 4 attempts to finally get years of accumulated crap of off my play field. After that, I don't have any kind of problem with junk getting under my protector.