Choose the correct roller nap thickness for your wall texture
Select a roller cover with the correct nap (fiber) length for your wall surface. Smooth walls (new drywall, plaster) use 3/16 to 1/4-inch nap. Lightly textured walls (eggshell finish, light orange peel) use 3/8-inch nap. Medium-textured walls (standard orange peel, light knockdown) use 1/2-inch nap. Heavily textured surfaces (heavy knockdown, stucco, brick) use 3/4 to 1-inch nap. The nap fibers must be long enough to reach into the texture valleys but short enough to avoid depositing excess paint that drips.
Why It Works
A roller cover that is too short for a textured wall leaves paint only on the peaks, creating a spotty "holidays" pattern that requires extra coats and still looks uneven. A roller cover that is too long for a smooth wall holds excess paint in the long fibers, which gets deposited as thick ridges, drip lines, and a heavy stipple texture. Matching nap to surface means even paint distribution in a single pass with minimal mess.
Tips
- 3/8-inch nap is the most versatile choice for typical residential walls with light-to-medium texture -- when in doubt, start here
- Microfiber roller covers produce the smoothest finish on smooth walls and leave almost no stipple; they cost $8-12 per cover vs $3-5 for standard polyester
- Cheap roller covers shed fibers that stick in the paint and are visible on the finished wall -- spend at least $5-8 per cover for quality brands (Purdy, Wooster, Benjamin Moore)
- For ceilings, use a 1/2-inch nap to carry more paint (reduces reloading frequency) and avoid thin spots in flat ceiling paint
- Roller covers labeled "high density" or "professional" have more fibers per square inch, hold more paint, release it more evenly, and produce fewer drips
- New roller covers should be pre-rolled (dampen with water for latex paint and roll on a clean surface) to remove loose fibers before the first use
- A 9-inch roller is standard for walls; a 4-inch mini roller is useful for tight areas behind toilets or between closely spaced windows
- Common mistake: reusing a dried-out roller cover from a previous project -- dried paint in the nap creates a stiff, uneven surface that sheds chunks into your fresh paint