Warning: I messed up a whole set of maple drawer fronts with the wrong finish...

I was in my shop in Tacoma last Thursday, spraying a water-based poly on some figured maple for a built-in. The first coat went on fine, but after the second, I got this awful milky haze over everything. Turns out the humidity spiked to 85% and the finish flashed off too fast. I had to stop the job, sand everything back down to bare wood, and wait two days for the weather to break. Lost about 8 hours of work and a quart of finish. Has anyone else run into this with water-based products in damp weather, or do you just switch to something else?

3 comments

3 Comments

finley_shah6422d ago

That exact thing happened on a big walnut table last spring. The shop felt dry but the finish went on cloudy. Now I keep a cheap digital hygrometer right by the spray area. If the humidity is over 70%, I just don't spray water-based poly that day. It's not worth the rework. Sometimes I'll use an oil-based wipe-on varnish instead if the job can't wait.

brooke_taylor22d ago

Did you check the dew point before you started spraying, or were you just going by the humidity reading? That haze is a classic sign of moisture getting trapped under the finish, and water-based stuff is brutal for that. I've learned the hard way to never trust a summer day in the northwest, even in the shop.

the_mia22d ago

You're right about that haze being a classic sign. My buddy had his whole kitchen cabinet job go milky because he only looked at the shop's wall hygrometer. He didn't know the wood itself was colder than the air. It was a total redo. That's why what @finley_shah64 said about the cheap digital hygrometer is smart, you need to know the exact spot you're working. My friend won't even think about spraying now without checking the actual dew point on his phone first. He says trusting the general room humidity is a sure way to ruin your week.