Is it absolutely required to sand between coats of polyurethane on wood floors?
Question:Most of everything I read says to sand lightly but someone told me they did not sand between coats and did not have a problem with the new coat adhering. I have already put one coat of fast drying Minwax polyurethane down. There is a new polyurethane from Minwax that says you do not have to sand between coats..but, I already have the other kind of Minwax down that does recommend sanding. I didn't know whether to sand and put down the new kind with 2 more coats without sanding in between OR put the same kind down without sanding and see what happens.
Answers:
You can coat without sanding between coats if you're recoating within a few hours of drying time in new work. If the finish has cured and is hard, then sand for proper adhision.
In the above, sanding scars the surface to give more resitance and total area of coverage.
On new work, the sanding will give you a better finish by smoothing the raised grain after the first coat and removing bubbles and imperfections thereafter.
On furniture you would want the smoothest finish achived by sanding and other methods of leveling.
However, all is wasted if you don't remove the sanding residue by vacuuming and tack cloth.
With the proper tools a pro can do a floor in no time without ever going on his knees.
So, it comes down to depending on what you're doing and how its used.
My hubby is in the hardwood floor business and it is neccessary to lightly sand in b/w coats otherwise the floors will not be smooth-rather, they'll end up scratchy.
He always sands in b/w coats of poly.
The sanding between coats makes the next coat stick better
You won't notice the difference until 5 to 10 years later when the top layer peels off
Keep using what you have been and sand in between. It is better to go that route than to start using a different product and mess the whole floor up. It will take less time to sand between layers.
Also, sanding is important because if you neglect to sand and just keep layering, the imperfections will stand out even more.
Sanding with 120 grit provide "tooth" for the new to adhere to the old. You may be all right without it but you are taking a chance of a problem that could only be solved by refinishing by sanding down to bare wood. A difficult project.
It might turn out just fine - but if it does not, do you want to have to go to all the expense and extra work of doing it over? When in doubt, do it right the first time - sand between coats.
No you don't HAVE to but I would really recommend it.It helps in a smoother coat as more coats are added and helps prevent scratches.You can use steel wool in place of sandpaper if you want.Sanding or steel wool makes for a glossy finish too.
However you decide to make ready for any successive coats, one thing to keep in mind is that Poly is susceptable to agitation. It should never be shaken and only stirred gently.
Any roughness at all is a result of air bubbles or the method of application, IE: Roller/Brush/Spray.
Gentle sanding with a fine grit paper will still have to be well cleaned after, or you'll end up with that grit in the next coat.
On small surfaces/jobs I never use sandpaper but a fine grade of steel wool.
A bit late now but I would have suggested a test first, on some similar type wood such as a scrap of birch veneer plywood. At this point you should research the reaction between the two and likely go with the more labor intensive procedure, using the same material.
Steven Wolf
Some of these answers are really funny.a lot of people have no clue...Anyways...Yes you sand between coats becasue wood breaths...and when you put a ploy coat on top of the wood and there is a barrier on the bottom the oxegen try to leave the wood causing the little bubbles that appear on the first couple of coats...This problem will stop, usually after the second coat...A third coat is a recommended amount of times but the more them better for wear...By the way poly will stick to almost anything.....
Yes, you should sand between coats of any kind of floor finish. Not only does sanding help the next coat to adhere better, but will give more "depth" to each coat. If you are using an electric floor sander, be sure that with each sanding, you use a finer grade of sand paper.. Personally I would not mix the 2 types of poly. They each are formulated with different ingredients or mixtures, and one might dissolve the other one some. Check with the Minwax Co.That's their biz!
Yup
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