The phrase "to cover the glass" means to place or apply something onto the surface of a glass object so that it is no longer visible or can be protected.
Sentences with «to cover the glass»
Below are featured articles, reports, releases and surveys on issues covering glass container recycling, jobs, and the environment. (GPI.org)
Then you can cover each glass with plastic wrap and refrigerate until set, at least 2 hours. (becauseilikechocolate.com)
I leave it on the counter in a little covered glass jar for a day, use it fresh and if there's any left, then refrigerate. (remonline.com)