House Painting Fundamentals: Preventing and Fixing Common Failures and Finish Defects

This chapter is a field guide to the most common paint failures and finish defects you’ll see after a job is “done.” Each section is organized the same way: what it looks like and why it happens, what to do immediately, how to correct the surface, and which primer/paint system prevents it from coming back.

Peeling (poor adhesion and/or moisture)

What it looks like and why it happens

Peeling is paint lifting off in sheets or chips down to a previous layer or bare substrate. It’s usually caused by poor adhesion (painting over chalk, dust, glossy surfaces, or weak old paint) and/or moisture pressure pushing the film off (leaks, wet siding, damp masonry, unvented bathrooms).

Immediate actions

• Stop coating the area—adding more paint traps moisture and increases failure.
• Check for active moisture: look for leaks, wet insulation, failed caulk joints, missing flashing, or condensation sources. If the surface is cool/damp to the touch, pause.
• Perform a quick adhesion check on surrounding paint: scrape with a putty knife; if it lifts easily beyond the obvious peel, the failure zone is larger than it looks.

Surface correction steps

1. Remove all loose paint to a sound edge (scrape, then sand/feather the perimeter so the transition can’t be seen).
2. Expose and stabilize weak layers: if multiple layers are failing, continue removal until you reach a firmly bonded layer or the substrate.
3. Address moisture source before repainting. Do not rely on “breathable paint” to solve bulk water problems.
4. Spot-prime bare areas and any chalky/porous zones with the correct bonding/sealing primer (see system below).
5. Recoat with full coverage over the repaired area, extending beyond the feathered edge to blend.

Primer/paint system to prevent recurrence

• Exterior wood/siding (adhesion-driven peel): high-quality exterior bonding primer on bare/feathered areas, then two coats of premium exterior acrylic.
• Chalky masonry or old oxidized paint: masonry conditioner or penetrating sealer designed for chalk/porosity, then acrylic masonry coating.
• Moisture-prone interiors (bath/laundry): stain-blocking/bonding primer where needed, then a bathroom-rated acrylic with mildewcide; ensure ventilation is corrected.

Flashing (porosity differences and patch telegraphing)

What it looks like and why it happens

Flashing is uneven sheen or color that appears in certain angles—often over patches, spackle, joint compound, or areas that were sanded differently. The root cause is uneven porosity and absorption, which changes how the paint film forms and reflects light.

Immediate actions

• Confirm it’s flashing by viewing under raking light (a flashlight held close to the wall) and from multiple angles.
• Do not keep “spot painting” the shiny/dull areas; that usually makes the map worse.

Surface correction steps

1. Sand the flashed area lightly to knock down texture ridges and unify the surface (avoid cutting through to paper on drywall).
2. Prime to equalize porosity: apply a drywall sealer/primer over the entire affected plane (wall section from corner to corner is often required).
3. Repaint the full plane with consistent roller nap, pressure, and wet edge. Maintain uniform film build.

Primer/paint system to prevent recurrence

• Drywall with patches: dedicated drywall primer/sealer over the whole wall (or at minimum from natural break to break), then two finish coats.
• High-sheen finishes: prioritize full-wall priming and uniform sanding; higher sheens magnify porosity differences.

Blistering (heat and/or moisture)

What it looks like and why it happens

Blistering appears as bubbles in the paint film. Moisture blistering is caused by water vapor trying to escape through the coating. Heat blistering can happen when the surface gets too hot (direct sun on dark colors, hot metal) and the film skins over before solvents/water escape.

Immediate actions

• Stop painting in direct sun/heat and move to shaded elevations or different times of day.
• Pop a blister and inspect: if the underside is damp or the substrate is wet, treat as moisture-driven; if dry and powdery, heat/solvent entrapment is more likely.

Surface correction steps

1. Let the substrate dry fully if moisture is involved; correct the moisture source (leaks, wet masonry, condensation).
2. Scrape/sand blisters down to sound film; feather edges.
3. Prime exposed substrate with the appropriate primer (bonding or masonry sealer depending on surface).
4. Recoat under proper conditions (surface temperature within product limits; avoid rapid heating; follow recoat windows).

Primer/paint system to prevent recurrence

• Moisture-prone substrates: use a primer designed for that substrate (masonry sealer/conditioner for porous masonry; bonding primer for wood) and a breathable acrylic topcoat where appropriate.
• Heat-prone areas: use coatings rated for the substrate and temperature exposure; apply when surfaces are cool and stable (morning/shade), and avoid excessive film build.

Cracking (brittle film and/or excess build)

What it looks like and why it happens

Cracking is a network of splits in the paint film. It often results from a brittle coating (aged alkyds, overly hard films) or from applying paint too thickly so the surface cures differently than the layer beneath. Movement in wood and joints can accelerate it.

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Immediate actions

• Identify depth: hairline cracks in the topcoat may be correctable; cracks that go through multiple layers usually require more aggressive removal.
• Stop adding coats—thicker films tend to crack more.

Surface correction steps

1. Remove failed film: scrape and sand until remaining paint is firmly bonded; feather edges.
2. Spot-fill if needed (only after the surface is stable) and sand smooth.
3. Prime bare areas with a bonding primer compatible with the topcoat.
4. Apply thinner, even coats per spread-rate guidance; avoid “one heavy coat” thinking.

Primer/paint system to prevent recurrence

• Over old brittle coatings: bonding primer to lock down edges and improve adhesion, then flexible exterior/interior acrylic topcoats applied at correct film thickness.
• High-movement exterior wood: premium exterior acrylics (more flexible) rather than overly hard films; maintain joints and end-grain sealing.

Alligatoring (severe cracking from incompatibility and aged layers)

What it looks like and why it happens

Alligatoring is a deep, patterned cracking resembling reptile skin. It’s typically caused by applying a more rigid coating over a more flexible one, coating incompatibility, or thick, aged paint layers that have lost elasticity.

Immediate actions

• Assume the system is structurally unsound in the affected area; spot fixes rarely hold if the underlying stack is failing.
• Check surrounding areas for similar patterning—this often spreads beyond the obvious section.

Surface correction steps

1. Remove the cracked paint stack to a stable layer or substrate (scraping, sanding; in severe cases, more intensive removal methods may be needed).
2. Feather transitions carefully; alligatoring edges are thick and telegraph easily.
3. Prime for bonding and uniformity across exposed substrate and remaining sound paint.
4. Rebuild with compatible coats at proper thickness.

Primer/paint system to prevent recurrence

• Compatibility-focused system: bonding primer designed to bridge old coatings and bare areas, then two coats of high-quality acrylic finish. Avoid stacking hard, brittle coatings over flexible ones.
• When in doubt: do a small test patch (primer + topcoat) and evaluate adhesion and film behavior after curing.

Mildew (moisture and insufficient mildewcide)

What it looks like and why it happens

Mildew shows as black/gray speckling or smudges, often in shaded, damp, low-airflow areas (north walls, soffits, bathrooms). It grows on dirt/film on the surface and thrives when moisture persists and the coating lacks adequate mildewcide protection.

Immediate actions

• Confirm it’s mildew (not soot or staining): a small test cleaning area should lighten if it’s biological growth.
• Do not paint over it; it will bleed through and continue growing.

Surface correction steps

1. Kill and remove growth with an appropriate mildew remover/cleaner per label directions; scrub and rinse as required.
2. Allow full drying before priming/painting.
3. Prime stained areas if discoloration remains (use a stain-blocking primer suitable for the substrate).
4. Improve conditions: increase ventilation, reduce condensation, trim vegetation, improve drainage—otherwise mildew returns regardless of paint quality.

Primer/paint system to prevent recurrence

• Exterior shaded/damp zones: primer as needed for stains/adhesion, then exterior acrylic formulated with mildewcide.
• Bathrooms/laundry rooms: spot prime stains, then a bath-rated acrylic with mildewcide; pair with effective exhaust ventilation and humidity control.

Tannin bleed (wood resins and extractives)

What it looks like and why it happens

Tannin bleed appears as yellow-brown stains that migrate through paint, common on cedar, redwood, and some knots in softwoods. Water-based topcoats can draw tannins to the surface if the wood isn’t properly sealed.

Immediate actions

• Stop applying finish coats once staining appears; more coats of standard paint often won’t stop it.
• Identify the source: knots, boards with heavy extractives, or water intrusion washing tannins out.

Surface correction steps

1. Let the surface dry if moisture is present; correct any water entry that’s mobilizing tannins.
2. Wash and lightly sand stained areas after dry to remove surface residue and improve primer bond.
3. Apply a true stain-blocking primer over the stained wood (often best as a full-board or full-area application to avoid picture-framing).
4. Recoat with finish paint after the primer cures per label.

Primer/paint system to prevent recurrence

• Cedar/redwood/new wood with extractives: stain-blocking primer designed for tannins, then two coats of premium acrylic exterior paint.
• Knotty wood: spot-seal knots with stain-blocking primer before full priming/topcoating.

Surfactant leaching (brown streaks on fresh latex)

What it looks like and why it happens

Surfactant leaching shows as glossy, sticky, brownish streaks or drips on the surface of freshly applied waterborne paint—often after cool, damp nights, heavy dew, fog, or poor airflow. Surfactants are paint ingredients that help with flow and color acceptance; under slow-dry/high-humidity conditions they can migrate to the surface.

Immediate actions

• Do not repaint immediately; recoating can trap the issue and create permanent sheen differences.
• Allow extra dry time and improve airflow/temperature if possible.

Surface correction steps

1. Wait for full cure (often several days depending on conditions) so the film can harden.
2. Wash off residue with mild soap and water using a soft sponge; rinse and let dry. Avoid aggressive solvents that can soften the film.
3. Evaluate sheen uniformity under raking light; if staining or sheen differences remain, apply one uniform finish coat over the full plane.

Primer/paint system to prevent recurrence

• Condition control is the main prevention: apply within recommended temperature/humidity ranges and avoid painting when dew/fog is expected during early cure.
• Product choice helps: premium acrylics often resist surfactant leaching better; follow spread rates and avoid over-rolling as the paint tacks up.
• Priming is not usually the fix unless there are underlying stains or porosity issues; this is primarily a curing-environment defect.

Quick reference table: defect-to-fix mapping

Final quality-control walkthrough (before you leave the job)

1) Raking light inspection (find what overhead light hides)

• What to use: a bright handheld light (or strong work light) held close to the surface at a low angle.
• What it reveals: flashing, lap texture, ridges, holidays (missed spots), edge build-up, patch telegraphing, and roller lines.
• How to do it: scan each wall from multiple angles; check around windows/doors, above baseboards, and across repaired areas where porosity changes are common.

2) Touch-up rules by sheen (avoid “picture framing”)

• Flat/matte: touch-ups are most forgiving, but still use the same tool (roller/nap) and apply beyond the defect to blend. If the wall is large and light hits it strongly, repainting corner-to-corner is often cleaner than multiple touch-ups.
• Eggshell/satin: touch-ups can flash. Prefer repainting the entire wall plane when the defect is noticeable under raking light. If you must touch up, lightly scuff-sand the area, use identical application method, and feather outward.
• Semi-gloss/high-gloss: spot touch-ups almost always show. Plan on repainting full trim lengths or full panels. Maintain consistent film build and brush/roller pattern.
• Color and batch control: use the same product line, sheen, and ideally the same batch; if not possible, box paint together before application to reduce variation.

3) Documentation for future maintenance (make the next repair easy)

Create a simple job record and leave it with the homeowner/property file. Include:

• Product list: primer(s) and finish paint(s), including manufacturer, product name, line, sheen, and color code.
• Where used: map by room/elevation and substrate (e.g., “north siding,” “bath ceiling,” “trim”).
• Application notes: number of coats, any additives used, and any special conditions (e.g., stain-blocking on knots, mildew-prone wall).
• Dates: application date(s) and cure-sensitive notes (e.g., “avoid washing for X days”).
• Maintenance triggers: what to watch for (returning moisture, recurring mildew, new staining) and what product to use for touch-ups.

QC Checklist (example) 
- Raking light scan: walls/ceilings/trim 
- Defects corrected: runs, holidays, flashing 
- Touch-ups: full-plane vs spot noted 
- Products documented: primer + topcoat + sheen + color 
- Photos taken: before/after + labels