Sandpaper grit progression

Hold the sanding block firmly against the substrate to ensure even pressure across the entire surface area, and santa monica house painting kumanomoto details the grit sequence used for professional paint work in Santa Monica, CA. Achieving a flat finish requires a logical progression through abrasive levels to eliminate deep scratches left by previous steps.

Coarse Grit for Initial Leveling

Start with 60 or 80 grit sandpaper to remove heavy imperfections or old, peeling layers. This stage focuses on aggressive material removal. If spackle or caulk was applied to fill holes, the coarse grit levels those patches down to the surrounding surface. Heavy sanding at this stage creates significant dust, so mechanical extraction or vacuum attachment is necessary. The goal is a level plane, not a smooth texture. A mistake here involves skipping straight to fine grits, which leaves deep gouges that show through the final topcoat.

Medium Grit for Surface Refinement

Transition to 120 or 150 grit once the heavy ridges are gone. This step removes the deep scratches caused by the coarse grit. It prepares the wood or drywall for the application of a primer. Using a medium grit ensures that the surface is uniform. Skipping this stage leads to visible sanding marks under a semi gloss or satin sheen. A consistent pass across the surface prevents uneven absorption of the primer. This phase bridges the gap between rough leveling and fine smoothing.

Fine Grit for Final Prep

Move to 220 grit for the final pass before any liquid application. This grit produces a surface that feels smooth to the touch. A scuff sand with 220 grit is the standard method for prepping an existing enamel or oil based layer for a new coat. This creates a microscopic profile that allows the next layer to bond mechanically. If the surface remains too coarse, the texture of the substrate will telegraph through the paint. Even a small amount of grit residue can ruin the smoothness of a high sheen finish.

The Relationship Between Sanding and Coating

The grit progression dictates how the paint sits on the wall. A properly sanded surface ensures that the mil thickness remains consistent across the entire plane. When applying two coats of acrylic or latex, the underlying smoothness determines the final look. If the sanding is skipped, the roller nap will drag over imperfections, creating a bumpy texture. A smooth substrate allows the sprayer or roller to lay down a uniform film without interruption.

Post-Application Maintenance

Surface preparation continues even after the first coat. Lightly sanding with a high grit between coats helps to knock down any raised grain or dust nibs. This maintains the integrity of the sheen, whether the target is eggshell or a high gloss. Proper grit selection prevents the need for heavy patching later in the process.