Roll Liquid Masking Onto Window Glass Instead of Taping It Off

The Problem

Painting window sash and muntins means masking every pane — cutting tape to length, pressing it into corners, and still getting creep under the edges. On a room with divided-light windows, the masking takes longer than the painting, which is why it gets skipped and the glass gets scraped instead.

The Technique

1. Buy liquid masking film — a paint-on masking product sold by the quart (around $25, and a quart goes a long way).
2. Roll it directly onto the glass with a standard paint roller. Precision doesn't matter: going over the edge onto the sash is fine, because paint goes over it next.
3. Let it dry until it turns clear — that's the ready signal.
4. Paint the window without babying the glass. Brush, roll, or spray right over the masked panes.
5. When the paint is dry, score along the edge of each pane with a utility knife.
6. Peel. The film comes off in one sheet, taking the overpaint with it and leaving a perfect paint line at the glass — 15 to 20 seconds per window.