Edding 780 waterproof paint pen, white 0.8 mm

For use with light and dark glass, fitted with a 0.8 mm tip.

When grinding your glass, the ink may come off the glass pen, this is less likely to happen with a lacquer pen.
Let the drawn line dry well before grinding or cutting. If this does not help sufficiently, you can rub the dry line with a thin layer of Vaseline or labello.

Closing the cap tightly will prevent the pen from drying out.