Seal the Tape Edge Before the Color Coat and Bleed-Through Can't Happen

The Problem

You tape the line, you paint over it, you peel it back — and there's the fuzz of bleed-through, even with the expensive tape. Paint is a liquid and tape edges have microscopic gaps; brushing straight across the tape forces color into every one of them.

The Techniques

Three levels, from better to bulletproof:

1. Press hard and brush upward. Burnish the tape edge down firmly, then stroke up along the tape rather than down into it — you're no longer driving paint at the gaps. Better, but as the demo shows, still not perfect.
2. Seal the edge with the wall color first — the preferred method. Before the new color goes anywhere near the tape, paint along the tape edge with the existing wall color (whatever's behind the tape). Let it dry, then apply your top color. Anything that bled under the tape is the wall's own color — invisible — and the top color meets a tape edge that's already sealed. Perfect line, every single time.
3. No wall color on hand? Clear paintable sealant. Run a thin bead of clear paintable caulk along the tape edge, smush it into the gaps with a finger, and paint your color right over it before the sealant skins. Same principle: the gaps are pre-filled with something invisible.