How to Fix Paint Flashing and Uneven Sheen on Drywall Patches
Alligatoring (patterned cracking resembling reptile hide) occurs when a rigid, hard-drying topcoat (such as an oil-based enamel) is applied over a soft, flexible, or uncured primer/undercoat, or when multiple layers of oil paint lose flexibility over decades. You cannot simply paint over alligatoring; you must completely scrape or heat-strip the cracked layers down to bare sound substrate, sand smooth, apply a slow-curing exterior bonding primer, and recoat with flexible 100% acrylic paint.
Published 2026-03-01 · Updated 2026-03-01 · 9 min read
Why Alligatoring Paint Cannot Be Sanded Flat and Painted Over
The deep cracks in an alligatored paint film penetrate through multiple paint strata down to wood or primer. If you paint directly over alligatoring, the new paint will sink into the cracks within 60 days, telegraphing the exact same jagged pattern to the surface.
Worked Example: Restoring 6 Historic Alligatored Window Sills
Restoring exterior cedar sills with 60 years of cracked oil enamel buildup.
Complete stripping to bare wood provides a fresh, flexible coating system lasting 15+ years.
What is the difference between checking and alligatoring?
Checking consists of shallow surface micro-cracks in the topmost coat, whereas alligatoring consists of deep, wide fissures through all paint layers.
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Sources
- NPS Preservation Brief 10: Exterior Paint Problems on Historic Woodwork — National Park Service