Why epoxy turns cloudy or milky
Short answer
A milky haze through the whole pour usually means cold resin full of microbubbles or moisture from the wood or the air. A white film on the surface is often amine blush. A dull, scratched look after sanding is not a defect and clears under the next coat.
“Cloudy” covers several different defects. The fix depends on where the haze is: all the way through the pour, only on the surface, or only after sanding. Start by looking at a cross-section edge or shining a light through the piece.
Haze through the whole pour
Cold resin and microbubbles
ArtResin explains that cold resin thickens and can turn cloudy or milky, because very small bubbles stay trapped in it. Its fix is to let the resin warm up to room temperature before you start, or to warm the closed bottles in water (ArtResin).
Clue: the haze is even, and the resin poured slowly and looked thick.
Moisture from the wood or the room
TotalBoat warns that unsealed porous surfaces and wet wood can lead to bubbles, cloudiness and a poor cure, and that a stable workspace helps reduce trapped moisture and surface clouding in slow-curing deep pours (TotalBoat).
Clue: the haze is worst near the wood, or appeared in a humid or unheated room.
Poor mixing
MAS lists improper mixing as the likely culprit for resin that is soft, sticky or full of micro-bubbles (MAS Epoxies).
Clue: streaks or patches of haze, sometimes with soft spots. See soft or tacky epoxy.
A white film on the surface only
If the body is clear but the surface has a whitish, waxy or greasy film, the likely cause is amine blush. EcoPoxy describes blush as a white, wax-like film that forms when the hardener reacts with carbon dioxide and water in the air (EcoPoxy). It is removed with water, not solvent; see the amine blush page.
Clue: the film wipes or scrubs off with warm, soapy water, and the resin underneath is clear.
Dull and scratched after sanding
A sanded surface looks hazy because sanding scratches scatter light. ArtResin notes that the surface may look cloudy or scuffed after sanding, and that this disappears when the next layer is poured (ArtResin).
Clue: you sanded it. Recoat or polish; nothing is wrong with the resin.
Diagnosis table
| Where the haze is | Likely cause | Prevention |
|---|---|---|
| Evenly through the pour | Cold resin, microbubbles | Warm materials into the published range before mixing |
| Near the wood | Moisture or air from the wood | Dry wood; seal coat first |
| Streaks or patches | Poor mixing | Mix for the full time, scraping sides and bottom |
| White film on top | Amine blush | Avoid humidity and fuel-burning heaters |
| After sanding | Sanding scratches | Recoat or polish |
Can it be fixed?
A surface film can be washed off, and a sanded haze disappears under a new coat. Haze locked inside a cured pour cannot be reached from the surface. For surface imperfections in a coating, ArtResin’s repair is to sand the whole surface, remove the dust and pour a fresh coat (ArtResin); for a deep pour, ask the manufacturer before deciding. Next time, check shop and material temperatures with the temperature and timing helper and seal the wood first (how to seal wood).
Sources
- ArtResin. FAQ. Accessed September 30, 2026.
- TotalBoat. Table Top vs Deep Pour Epoxy. Accessed September 30, 2026.
- EcoPoxy. Support and FAQs. Accessed September 30, 2026.
- MAS Epoxies. The Ultimate Guide for Mixing Epoxy Resin. Accessed September 30, 2026.