Quoted from jukehero1:I have bought a number of machines that were in unheated but attached garages and every single one of them has playfield planking.Don't even consider leaving a silkscreened backglass out there.It's just a matter of heating and cooling cycles,heat up during the day...cool down at night...etc.Even just 5 or 10 degrees but with that happening every single day,not to mention even more extreme jumps during certain times of the year and you will have a ruined playfield.
Well Im sure humidity in your area has a lot to do with that too.