Marker stays well on glass if you want to wait for it to dry. The problem is, who wants to wait for the mark to dry. Do we wait hours, days for each mark? It’s just not practical. So there are a few techniques that I’ve come up with to keep us moving forward with cutting and grinding.
I’ve tried all kinds of markers over the years and I found a silver sharpie has much better staying power. I’m not sure what they use that’s so different from the black but it stays so well when it dries sometimes I have to use 0000 steel wool to get it off.
I have also used a gold paint pen. It has good staying power but only when you let it dry. The Nice thing is it dries quickly.
To help these markers and paint pens stay even better, smear petroleum jelly over the marks to keep it from coming off too quickly while grinding or saw cutting. Make sure to apply a thin layer of the jelly. Excess jelly can get in the inner workings of your saw and bind it up or capture additional grinder grit where you don’t want it.