I like using a orbital sander with #40 grits, no firgue 8's, just back and forths until all the gasket grime is gone. I use reel corse finish so the new gasket sticks good the head. If I was forced to yous glass it would block the view of the locmotums travelling daly past the house,,,and reely how can you sand your heads and stuff in the vertikal, another allturnituv wood be a grave stone,,,,they are slicker than than snot on a door nob.....(I'm avacating not you borrow one) geer head types mite search grammarikally's wrong one offs from toom stone supplyers (dykeslickits letter grinders),,,,,hey there flat!!!!!!!!!!!!!,,,,,,,,,let me know if flatter stuff is better
