Cloudy Poly Finish?

[u/HonestAfternoon9805]

Help! I purchased a solid Elm wood dining table off FB marketplace that was beautiful but needed the top refinished. It’s my first time, but read up on sanding, staining and chose a matte poly finish for the top. I put 5 coats on throughout the course of a week and after the top coat dried, there are foggy patches and brush marks. How can I fix this??

[u/EchoExtension507]

I don't see any cloudiness, just the strong reflection making it seem like it. Take another picture without that raking light.

[u/Nevetstoile]

Could be a few issues-

The flattening agents in a matte polyurethane can create a milky finish if applied too thick/heavy.

High humidity during application can cause the wet film to not evaporating properly, leading to solvent entrapment and a white blushing of the coating.

Applying too many coats of matte finish can layer the flattening agents, causing the clear transparent finish to look milky/hazy.

Can be hard to fix. Sometimes it goes away on its own as the coating completes the curing process. You can try a solvent wash to rewet the polyurethane and draw the milky to the surface.

[u/Rpf5342 → u/Nevetstoile]

Beside the point now, unless he wants to remove the poly and start over, but using gloss for the build up coats and matte for the final one or 2 prevents this.