Thread: Flattening Glass Plate....

I thought that float glass plate was reasonably flat. I was wrong. I picked up 4-¼ inch glass plates (3" x 11") from a local glass/mirror place and lapped them on my DMT lapping plate. All four were certainly not flat but flattened easily with some effort on the lapping plate. I did it dry. I got these plates in anticipation of receiving some lapping films to evaluate how the new lapping films compare to stones, cubic boron nitride slurries on various substrate, and strops.

All four plates needed flattening. Two plates has several high spots that required significant work to flatten them (about 30 minutes of lapping). The other two, while needing flattening as well, had minor high spots that leveled off within about 10 minutes of lapping. The DMT metal lapping plate works well at flattening glass.