Paint a Razor-Sharp Two-Tone Wall Line: Level, Tape, and Seal With the Base Color

The Problem

A two-tone wall lives or dies on one line. Get it slightly off-level and every shelf and door frame in the room announces it; let paint bleed under the tape and the color break looks homemade. Both failures are decided before the second color ever opens.

The Technique

A decorator's full sequence for a horizontal color break:

1. Sand the walls and woodwork, then wipe the dust off. Dust left on the wall keeps paint from adhering and bubbles it — fatal when tape is going over that paint later.
2. Paint the top section first — two coats — and leave it a full 24 hours to properly dry before taping over it.
3. Measure and mark the line height, then draw the line with a level. Don't trust anything in the room as a reference: even in new builds, nothing is straight.
4. Tape with a delicate-surface masking tape, set just slightly above the drawn line so you're painting over the line itself. Apply the tape in one continuous run where you can, then press it down with a damp cloth.
5. Seal the tape edge with the base color first. Brush the top section's color along the tape edge and let it dry. If anything seeps under the tape, it's the same color as what's underneath — invisible.
6. Paint the bottom color: brush the edges and sides, then roll right up to the tape with a small roller. Two coats.
7. Peel the tape at an angle once done, pulling away from the line so the dried edge doesn't chip.