Topic: Reflections on the mirror
Two thoughts. If you buy a mirror for a print bed, it likely has a sticker and/or rubber pads on the back. Get those off and the gum too. Goof Off Pro or acetone should get it. Any gunk left on the mirror back will insulate or cause an air gap between the mirror and the heated bed and maybe slow warm ups, uneven heat and part warping.
Have a second mirror on hand to "hot swap" when the first on gets gunked up. Place the second mirror on the heated bed to warm while you clean up the first mirror. When you come back, the second miror will be hot and ready to print, saving you a few minutes.
