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. In this case, the jargon actually means something.
Also known as “buff and coat”.
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.
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. 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. These cause 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. This 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 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 second photo above is intact, but a recoat won’t help much. It is physically possible to recoat floors like these, and even have the new coat bond well. But the damage will still be visible through the fresh coat of finish, effectively preserved under plastic.
Be wary of floors that look like they can be recoated:
Scenario 1: Finished with waxes, maintained with silicon or oil soaps
Floors with confirmed layers of natural or man-made 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 2: Prefinished with aluminum oxide coating
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. If you are in the City of St. Paul proper and the City of Roseville in Minnesota, consider hiring Pete’s to refinish your floors.
Procedure for a screen and recoat
This assumes you are coating a floor with an existing, conventional urethane coating. This procedure will work over any CURED urethane finish, both oil-based and waterborne.
Step 2: Assume the floor is contaminated!
Even if you swear you’ve never used anything but water to clean the floor and you’ve tested for waxes, you should still assume that there could be an invisible substance on the floor that could cause major trouble.
Use Pallmann Clean Strong diluted 10:1 with water, sprayed directly on the wood floor, then scrubbed with a white polishing pad under the buffer. Use old, water-dampened towels to wipe any residue loosened by the Clean Strong, and allow to dry. You won’t be sorry!
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 200sqft to screen, we recommend using a buffer. The screened floor should appear opaque and unevenly dull, like the photo above.
Step 4: Vacuum, then wipe up remaining dust with a clean rag
Vacuum the floor thoroughly and then tack with a clean rag lightly dampened with the appropriate solvent. This includes water for waterborne finishes, paint thinner for solvent-based finishes. DO NOT USE A COMMERCIAL TACK CLOTH! Read our story about our customer who used a commercial tack cloth.
Step 5: Finish
Apply your finish according to manufacturer’s instructions. The finishes we sell are applied with either a 3/8″ nap roller (Pallmann finishes) OR an 18″ t-bar (Bona or DuraSeal) for the larger open areas while cutting in edges and details with a pad painter.
Typically a screen and recoat involves adding just one coat over your existing finish. But in houses with high wear, a second coat is a great idea. Be careful though if you are trying to just add some of your extra or leftover finish just to one room. Make sure your stopping point lines up with a wall or at least the long edge of a board. Don’t just stop coating in a doorway, unless the long board edges of the flooring run parallel to the doorway opening.
Step 6: Dry 24+ hours
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). Its luster will be dulled by any further buffing or polishing.
Pete’s Bonus Tips
Test before you recoat!
If you don’t know the cleaning or maintenance history of the floor you want to recoat, STOP!
If that floor has been cleaned with Murray’s Soap Oil (you know what we mean), Orange Glo or any acrylic waxes like Future or Mop & Glo, a modern polyurethane will not bond to it.
Yes, even if you screen it aggressively first, you are likely to experience “crawling,” the dreaded “fish-eye” or just widespread peeling after the finish is applied.
How to determine if you need to chemically strip the floor before recoating
Do these tests to determine if you need to chemically strip the floor before recoating
To test for a grease-based residue like wax or oil-soap
In a low-traffic area that has been cleaned thoroughly (behind a door is a good spot because it was usually cleaned or coated, but hasn’t been worn off – closets and pantries are not good test areas because those areas are often skipped during the cleaning process) place several drops of mineral spirits (also known as paint thinner) and let them sit for 2-3 minutes.
Wipe up the paint thinner with a clean, white rag. If there is a brown or yellow residue on the rag, or if the residue feels waxy, a contaminant is present. Scrub the floor with a small amount of paint thinner and steel wool (buffers are good for this) until all residue is removed.
Test for acrylic waxes or polishes
In a low-traffic area that has been cleaned thoroughly (behind a door is a good spot because it was usually cleaned or coated, but hasn’t been worn off – closets and pantries are not good test areas because those areas are often skipped during the cleaning process) place a large drop of a 1:1 water-ammonia mixture and allow to sit for 5-10 minutes.
If the area turns white, then a floor polish or wax is likely present. Scrub the entire area with a 4:1 water-ammonia solution until all residue is removed.
What you should know about modern waterborne finishes.
Waterborne finishes have improved exponentially since they first appeared on the market.
Modern air quality regulations have encouraged manufacturers of waterborne polyurethane to step up their game.
Waterborne finishes are much more resistant to wear and solvents than they were even 15 years ago (please note that we're referring to respected finish manufacturers; inexpensive, big-box store waterborne finishes can still perform poorly).
They are also much less prone to foaming and will level better than they used to.
So, don't just categorically dismiss this class of finishes, but make a educated decision based on what we do know about them.
Five things to know about waterborne finishes
- Waterborne finishes, unless their container says otherwise, have no color. None. Especially compared to oil-based polyurethane. Even Amberseal can't warm a floor up as well as oil poly. There are ways to get around this - read about Bona's oil-based Dri-Fast Sealer designed for use under their line of waterborne finishes.
- You don't need to use a respirator for the waterborne finshes we sell, but that doesn't mean they don't contain toxic solvents. They just contain smaller quantities of them. People who are respiratorially sensitive or pregnant should still stay out of the property during the coating process.
- Waterborne finishes clean up with water; don't use paint thinner, turpentine or alcohol.
- Waterborne finishes are more weather-sensitive than solvent finishes. You'll find that waterbased finishes will take longer to dry in humid weather, but set up with disturbing speed on those hot, dry windy days.
- Don't let your waterborne finish freeze! Once it freezes, it's ruined.