Homeowners sometimes call us after a DIY paint job didn't turn out right. The paint is peeling near the trim. There are roller marks. The finish looks uneven. The color looks patchy even after two coats. They bought decent paint. They used decent rollers. So what went wrong?
Almost always, it's prep. Not the paint, not the tools — the surface preparation. In 27 years of painting homes across Nebraska, I've come to believe that prep work accounts for roughly 80% of the final result. The paint is just the last step. What happens before that determines everything.
STEP 1: CLEAN THE SURFACE
Paint does not stick well to dirty surfaces. This sounds obvious, but it's the most skipped step in DIY projects. Walls collect dust, grease (especially in kitchens), soap residue (in bathrooms), and hand oils near light switches and door frames. Paint applied over any of that will have adhesion problems within months — sometimes weeks.
For most interior walls, a wipe-down with a damp cloth and a mild TSP substitute solution is enough. Kitchens are a different story — grease splatters are invisible until paint peels away from them a year later. We degrease kitchen walls thoroughly before we touch a paintbrush. Bathrooms get attention too, especially around showers and window sills where mildew likes to hide.
Exterior surfaces need power washing — not just a garden hose rinse, an actual pressure wash to remove chalking, dirt, mildew, and failed paint particles. We let surfaces dry completely (typically 48 hours in Nebraska summer conditions) before priming.
FILLING, SANDING, AND SKIM COATING
Every hole, dent, nail pop, crack, and gouge needs to be filled before paint goes on. Paint does not hide surface imperfections — it highlights them. A flat sheen on a textured wall with unfilled dings will look terrible in raking light (light coming in at a low angle from a window or lamp).
For small holes and nail pops: lightweight spackle, let it dry, sand flush, done. For larger holes and cracks: setting-type compound (Durabond or similar) for the first fill because it doesn't shrink, then a skim coat of lightweight compound to finish.
Skim coating — applying a thin coat of joint compound over an entire wall — is the move when a wall has been textured and you want a smooth finish, or when a wall has heavy texture that's been painted over so many times it's starting to look like orange peel. It's extra time and labor, but the result is a wall that looks like new drywall. That's when people say a paint job transformed a room. It did — because we skim coated.
After all filling: sand everything. Not just the patches — the entire surface. Sanding gives the primer and paint something to mechanically grip. On glossy surfaces (like previously painted semi-gloss trim) sanding is non-negotiable — primer and paint will not bond to a high-gloss surface without it.
The test we use: After filling and sanding, we hold a work light close to the wall at a raking angle and scan the entire surface. Any remaining imperfections show up as shadows. If we see them with the work light, they'll show up in the finished paint job. We fix them now.
PRIMER: THE STEP MOST PEOPLE SKIP
Primer is not just thinned paint. Different primers solve different problems, and choosing the right one matters.
- Drywall primer (PVA primer) — Used on new or freshly patched drywall. Seals the paper and compound so they absorb the topcoat evenly. Skip it and you'll see "flashing" — shiny spots where the compound absorbed the topcoat differently than the surrounding wall.
- Stain-blocking primer — For water stains, smoke damage, crayon, markers, or any bleed-through situation. Shellac-based (Zinsser BIN) for the worst cases; water-based stain blockers for lighter staining. Regular paint over a water stain will let it bleed through, no matter how many coats you apply.
- Bonding primer — For slick or glossy surfaces that haven't been sanded enough. Grabs onto surfaces that normal primer would bead off of.
- High-build primer — For exterior surfaces with minor surface irregularities or previously chalking paint. Fills and levels as it primes.
On most interior repaint jobs we use a quality PVA primer as a base coat, tinted toward the finish color. This reduces the number of topcoats needed and ensures even color.
TAPING, MASKING, AND PROTECTING WHAT ISN'T BEING PAINTED
Good masking is what separates a clean paint job from one that looks like it was rushed. We use Frog Tape (not the cheap hardware-store blue tape) on all trim lines. The difference in bleed-through is significant. On textured surfaces we use the Frog Tape with the orange stripe designed specifically for textured walls.
Floors get covered with canvas drop cloths — not plastic sheeting, which moves and bunches and causes more problems than it solves. Furniture is moved out of the room when possible, or pushed to the center and draped. Outlets and switch plates come off entirely rather than getting taped around — it takes two minutes and the result is cleaner.
WHAT OUR PREP PROCESS LOOKS LIKE
When Martinez Painting shows up for an interior job, the homeowner is often surprised by how long we spend before the first drop of paint goes on. Here's a typical interior repaint sequence:
- Move and protect. Furniture out or centered and covered. Canvas drop cloths down on all floors. Outlet covers and switch plates removed.
- Clean the walls. TSP substitute wash on all surfaces. Degrease kitchen and bathroom walls specifically.
- Repair all surface damage. Fill nail holes, dents, cracks. Set any nail pops. Caulk gaps at trim and ceiling lines.
- Sand the entire surface. Not just patches — the whole wall, lightly, to scuff the existing paint and give the new coat something to grip.
- Prime. Spot-prime all patched areas at minimum. Full prime coat on new drywall, heavy stains, or significant color changes.
- Raking light inspection. Catch anything we missed before the topcoat goes on.
- Tape and mask. Frog Tape on all trim lines. Protect anything that isn't being painted.
- Paint. Now we paint.
Steps 1 through 7 often take longer than step 8. That's intentional. That's what a professional paint job actually is.