I haven't used this method in a while, simply because doing so removes the protective clearcoat from the playfield (or what's left of it anyway), but when I did use it, I used denatured alcohol, or 91%--but only if denatured wasn't available. School of thought is that you want to use an alcohol that has the least amount of water content as to not raise the woodgrain of the playfield.

Make sure to read this if you haven't already: https://pinside.com/pinball/forum/topic/cleaning-and-waxing-pinball-machines-vids-guide#post-2655687

GL.

91%. Be patient...too much pressure and you will start taking off the paint. Since this dissolves the clear coat, you are going to get some haziness but you can follow up right after with a clean rag with a little alcohol or naphtha on it. Just remember you are basically taking off the top coat so just keep it waxed afterwards as you have less protection in that spot.

I use novus 2 to get the haze off

Ive used both 70 or 90 alcohol straigtht with it, I assume technically the higher percent the better, but in actual practice whom knows.

Coil dust will work itself under the protector and the ball will slowly grind the dust into the playfield. Plus protectors play differently than playing on a playfield.

So if you dont use a protector the coil dust stays on the playfield and the ball rolls all over it grinding it into the playfield?

Is that what you are saying?

Wax alone won't be enough. Naked paint wears very quickly, wax or not.