Will my too shiny coat of polyurethane dull as it cures?

Q: Does poly finish become duller with time? My contractor did a patch in my oak floor and applied 3 coats of semi-gloss poly trying to match the old floor. The first two looked pretty good, but the 3rd (final) coat is really shiny. He claims that I just need to wait 30 days for it to fully cure and it will match. Does poly dull with time in this way?

Based on reading on your site, it seems like maybe he didn’t stir the coating properly before the last coat. He wants to wait a month, then buff with steel wool to dull the finish if it’s still shiny.

A: If the application is shiny when dry it won’t look any different at months end. All except gloss and hi-gloss have a percentage of a paste which is mixed in to lessen the shine. The best, most consistent product I’ve ever used is Poloplaz Primero. When I first tried it I commented to their sales manager this paste seemed suspended in the polyurethane and required very little mixing. He said they spent a few extra $$ to develop a way to make it so because a of people don’t mix their finishes enough. All the other finishes I’ve used saw the paste start to settle after mixing and doing so rather rapidly.

Another issue is regarding how fast the coating sets up. That paste has to have enough time to settle to the bottom of the film. If it doesn’t then you will end up with a finish that is shinier than anticipated.

Rubbing with very fine steel wool might help, but it still sounds tricky, and maybe hit and miss. It’s worth a try. If it doesn’t work then you either have to live with it or have another coat.

Follow-up: Thank you so much! I really appreciate this answer. I’d never really thought about how they actually get the different sheens in the coating, so it’s been fun to read more about it. Again, thanks for helping make the internet such a great resource.

How can we dull the finish a little bit more?

Related Q: We had old, scratched and worn floors in our hallway that we sanded. We applied 3 coats of gloss finish, as our local woodworking shop recommended. We did not sand after we applied the 1st coat of finish, but we did sand after the 2nd and 3rd coats. Then we applied a satin finish on top. However, we still have too much shine to the floors and most importantly we have a line between the old floor in the living room, and the dining room and the hallway. How can we dull the finish a little bit more and how can we get rid of the obvious line between rooms?

A: I always sand with fine abrasive after every coat of finish. Each coat needs to be thoroughly abraded to gain adhesion. Buffing thoroughly will essentially degloss the film. I hope you have sanded enough between coats.

You may not have stirred the satin enough to mix the flattener. The best polyurethane I’ve used is Poloplaz Primero. Their flattener stays mostly suspended in the finish and requires much less mixing. You will likely have to sand everything again (buff not totally sand down) and apply another thin coat.

As to the line across the doorway, if you are applying across the grain then it is about impossible. A closer match can be made when stopping along a board edge. Also, the age of the finish can be very difficult to duplicate. You could rub the entire floor down with super fine abrasive, like 1000 grit but it would be so laborious with no guarantee of it looking uniform, the easier way is to give it another coat.

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