What the heck is a screen and recoat?
A screen and recoat is the best-kept secret in the hardwood flooring world. But it shouldn't be, because it can save you money, labor and time over the life of your hardwood floor. Read on, and remember, the buffer is your friend.
If you have spent any time talking to your hardwood flooring professional (or reading the hardwood flooring blogs) you’ve heard the phrase “screen and recoat.” Here at Pete’s we know that people can toss around jargon like that in an attempt to sound knowledgeable, but in this case, the jargon actually means something.
The phrase “screen and recoat” describes the process of sprucing up an existing coat of polyurethane by top-coating it. (This is sometimes referred to as "buff and coat" because the screen is often driven across the floor by a buffer). But the inclusion of the word ‘screen’ is vital because in order to get a new coat to adhere to the old one you must lightly sand or ‘screen’ it.
A screen is just a mesh encrusted with abrasive particles. Because it is a mesh, there are fewer abrasive particles per square inch, making it generally less aggressive than sandpaper (a 120-grit sanding screen, for example, will be less aggressive than 120-grit sandpaper.)
Screens are also used under thick soft pads that further soften the cutting action of the screen. This is desirable because floor screening should only leave enough texture in the floor to allow a new coat of polyurethane to bond; screening should remove only a tiny fraction of the existing finish.
Part of a regular maintenance program
That was a long-winded explanation that only just hinted at the purpose of a screen and recoat. It is simply part of the regular maintenance of a hardwood floor that has been finished by polyurethane. Polyurethane is considered a protective sacrificial coat. Over time, the plastic in the finish is slowly removed by the friction of day-to-day living.
That layer gets thinner and more scratched each year—as it should—because its job is to keep damage away from the wood below. But if you let that protective coat deteriorate for too long, it will eventually expose bare wood to assaults from doggy toenails, coffee spills and baby drool, causing damage that can only be repaired by sanding the whole floor. This, you do not want.
So, every few years, well before the protective coat has grown too thin, you refresh it with another coat. The crucial word is “before;” you have to recoat a floor before you see damage, which is hard for some people because they think they’re leaving money on the table by top-coating what appears to be a perfectly good floor finish.
But polyurethane on floors is kind of like sunscreen on skin: not only do you need to put on a good thick layer before you expose it to the sun; you must re-apply it periodically because it wears off. Once sunburn begins to appear, it is too late to start applying protection. Protection is always less costly than the damage that results from not having it.
Can any hardwood floor be recoated?
Alas, no. Some floors are just too far gone to be saved by a simple recoat. If there is damage at the level of the wood on any part of the floor, including dents, deep scratches, wear spots caused by heavy traffic (look for the tell-tale gray patches at doorways or in front of the sink), UV discoloration around rugs, and pet stains. The finish on the floor in the photo at right is intact, but a recoat won't help much. While it is physically possible to recoat floors like these, and even have the new coat bond well, the damage will still be visible through the fresh coat of finish, effectively preserved under plastic.
And be careful with floors that look like they can be recoated
Scenario 1: Floors that have been finished with waxes (even acrylic waxes like Mop & Glo), or maintained with silicon cleaners or oil soaps are nearly impossible to recoat: a fresh coat of polyurethane simply will not bond to them. Even after stripping these floors with ammonia or paint thinner there can still be enough wax or soap buildup left behind to cause a bond failure.
Scenario 3: The floor was pre-finished with a modern, aluminum oxide coating. These finishes are so hard that mechanical screening doesn’t create enough of a bonding texture! Aluminum oxide finishes can be recoated, but they have to be etched chemically first. This is best left to a professional.
So, when should I recoat my floors?
That depends on how hard you live on your floors because, obviously, hard use shortens the life of a floor finish. We recommend that you start looking for signs of wear about three years after floors were sanded or last recoated, except for kitchens and exterior doorways. Start looking for wear there after just one year. If you have a visible pattern of scratch under chairs or in walkways, it’s time.
Why can’t I just sand the damaged areas?
You can, if the damage is contained along the grain direction of the boards. But if you try to sand off the wear across or perpendicular to grain of the floor, the repair will be evident and unsightly, as you can see in the photo at right.
In order to “spot-fix” a floor, you have to contain the sanding and refinishing within a single board or a fixed area bounded by board edges. Taping off a problem area helps, but it is still challenging to sand accurately inside such an intricate space and right up to the taped edges without scouring into the adjacent undamaged floor.
Procedure for a screen and recoat
Note: These instructions assume the floor is free of any contaminant that would prevent a bond with a coat of finish.
- t-bar and coater
- pad painter
- solvent that matches your finish
- watering can (this makes pouring out your finish easy and drip-free)
Step 1: Inspect the floor for anything that won’t screen out or could damage the screen such as staples, nails and loose boards. Scrape down any drywall compound or paint splatter.
Step 2: Vacuum floor and damp mop with a mixture of one cup vinegar to one gallon water. Make sure you wring your mop out thoroughly—there should never be standing water or puddles. Let the floor dry thoroughly.
Step 3: Use your favorite method to lightly abrade the top layer of finish: Sand around the perimeter of the room by hand with a 120-grit screen. For the middle of the floor you can use a pole sander with a 120-grit screen, or a floor buffer with a pad and a 150-grit screen. If you have more that 200 sq. ft. to screen, we recommend using a buffer. The screened floor should appear opaque and unevenly dull, like this:
Step 4: Vacuum the floor thoroughly and then tack with a clean rag lightly dampened with the appropriate solvent (water for waterborne finishes, paint thinner for solvent-based finishes).
Step 5: Apply your finish according to manufacturer’s instructions. Our preferred method is to use an 18" t-bar for the larger open areas while cutting in edges and details with a pad painter.
Step 6: Allow the finish to dry at least 24 hours before allowing foot traffic or replacing furniture. Contrary to popular belief, no further buffing is necessary after the finish dries; polyurethane dries to a pre-determined level of shine (the can will tell you whether it's satin or semi-gloss) and its luster will be dulled by any further buffing or polishing.
Need more help? Check out our article on working with sanders and edgers.