Volatile chemicals. Finish manufacturers have reduced the volatility and
try cleaning it with a wax cleaner. If scratches
strong odors of their products, but you should always limit your exposure to them by
and scuffs are limited, wax will be reasonably
wearing an organic-vapor respirator, long sleeves, and gloves when sanding old fin-
easy to remove by applying wax stripper or min-
ishes or applying new ones. Even fumes from water-based polyurethane are
eral spirits and wiping up the residue. Then apply
unhealthy to breathe, so as soon as finishes are dry to the touch, open windows to
a new coat of wax. However, if floors are badly
let vapors disperse. and sleep elsewhere until they’re completely dry.
abraded and can’t be buffed out, sand the floors,
fire and explosion hazards. Sparks or open flames can ignite chemical fumes
refinish them with a penetrating stain, and then
or dust. So before you start sanding or applying finish, turn off pilot lights for water
wax them. Even if you sand wax-sealed floors
down to bare wood, wax clinging to board edges
heaters, ranges, and furnace. also tape light switches down so they can’t generate a
may prevent a nonwax finish from adhering
spark. trash bags of moist sawdust or covered garbage cans full of oily rags can gen-
properly. (Get a second opinion from a profes-
erate enough heat to combust spontaneously, so don’t allow debris to collect on
sional floor refinisher.)
site. Empty sander bags often into a metal container safely away from the house and
other combustibles.
Test 2: Shellac or varnish. Find an area where
the finish is in poor shape and scrape it with your
lead paint and asbestos. Floors painted before 1978 may contain lead-based
thumbnail or a penny. If the finish flakes off, it’s
paints, so don’t sand them until you’ve had the paint tested, as suggested in chap-
shellac or varnish, which were good in their day
ter 18. lead paint is generally not a problem until the dust becomes airborne or it
but should now be sanded off completely and
flakes in an area where small children might eat it. old linoleum floors may have
replaced with polyurethane. If the finish doesn’t
been adhered with asbestos adhesive, which wasn’t banned until 1977. Here again,
flake, try test 3. If the abraded areas are small, try
asbestos is usually harmless if undisturbed, so first consult a local health depart-
restoring damaged areas by lightly sanding them,
ment to get the name of a test lab.
vacuuming and dust-mopping them well, then
applying a new coat of finish. If there’s not too
much sanding to do, you may not need to rent a
sander: A random-orbit sander with 100-grit or
120-grit sandpaper should do the job. Use a
P R O T I P
natural-bristle brush or a lamb’s wool pad to
apply shellac or varnish.
if you’re not sure what finish
was used on floors, first examine
Test 3: Polyurethane. In an inconspicuous
old paint and finish cans in the
place, brush on a small amount of paint stripper.
basement, garage, or workshop.
If the finish bubbles, it’s polyurethane. If it
the contents of the cans will
doesn’t bubble, the floors were probably sealed
almost certainly be useless, but
with a penetrating oil finish. If floor damage is
their labels may tell you what’s
limited, you may be able to touch up the pene-
on your floors.
trating oil with a similar substance, testing small
areas until you find a good color match. If the
finish is polyurethane, which is a surface finish,
Most rental companies offer drum sanders because their
sand the floor lightly if it is in good shape to help
paper clamping slots make changing sandpaper easy.
the new coating adhere. Fortunately, polyure-
Before accepting a rental drum sander, inspect slot lips for thane will stick to other polyurethane even if one nicks or metal spurs, which could damage wood floors.
is oil based and the other is water based. As long
Before leaving the rental company, learn how to insert
as the base coat is dry, it doesn’t matter whether
sandpaper so it’s tight to the drum.
you apply oil-based urethane over water-based
562 Chapter 20
urethane or vice versa. Of course, if the finish is
sand all engineered wood floors at least once or
P R O T I P
in bad shape, you should sand down the whole
twice, and thicker wear layers three to five times.
floor to bare wood and then refinish it.
EquiPMEnt
don’t use chemical paint strip-
rECaP: WHEn to
per to remove a floor finish, even
Most sanding equipment can be rented. Be sure
if the floor is painted. Strippers
rEMoVE Floor FiniSHES
to have a knowledgeable person at the rental
are caustic to wood and hazard-
ous to users, and even the small-
Sand floors to bare wood when:
company explain how to operate the machines
est residue—between boards, for
Floor finishes are gouged, pitted, or
safely, how to change sandpaper and adjust
example—can create adhesion
showing bare spots.
wheels and drive belts, and what size circuit
problems for the new finish.
breaker or fuse each tool requires. Finally,
Stains go below the surface, such as mold
inspect each piece of equipment. Sander drums
stains beneath potted plants.
and edger disks should be smooth and free of
Floorboards are irregular or uneven.
nicks or metal spurs that could scar floors. Check
New finishes won’t adhere to the
to see that sander wheels roll freely and that elec-
P R O T I P
flooring.
trical cords aren’t frayed or swathed in tape
You need to repair rotted or split boards.
because they have been run over by the sander.
Empty sander bags when they
The floor is thick enough to withstand
A large floor sander does most of the heavy
become about one-third full. as
a sanding.
bags fill up, they become less
sanding. Most professional refinishers favor large
efficient filters, and more dust
belt sanders, as shown in the photo on p. 556,
iS it tHiCK EnougH to Sand?
will stay in the air or on the floor.
because their belts are continuous, whereas
rental companies usually rent drum sanders
To avoid splintering wood floors when sanding
because the paper is somewhat easier to change.
them, keep at least 1⁄8 in. of solid wood above the
Typically, a special wrench or key turns a nut at
tongue of T&G flooring. The easiest way to check the end of the drum, which opens a paper-
the floor’s thickness is to remove a forced-hot-air
clamping slot on the face of the drum. Drum
floor register and look at the exposed cross sec-
sandpaper must be tight or it will flap and tear:
tion of flooring. If that’s not possible, pull up a
Use old pieces as templates for new ones.
threshold or a piece of trim and bore a small hole
Caution: A drum sander is a powerful
to expose a cross section. Or drill in a closet,
machine that can gouge even the hardest wood,
where no one will see the hole. If you’ve got engi-
so always keep the machine moving when the
neered flooring, its wear layer (top veneer layer)
sanding drum is down. A lever on the handle
won’t be very thick to start with—5⁄32 in. is typi-
lowers or raises the drum. Start the machine
cal—so start sanding with a less aggressive sand-
only when the drum is up. Then, as you walk,
paper, as suggested in “Floor-Sanding Materials”
gradually lower the drum.
at right. Manufacturers contend that you can
Floor-Sanding Materials*
zzzzzz How deep Can You Sand?
ENGINEERED
SOLID-WOOD
tyPe of material grit size
when to use
FLOORING
FLOORING
Wear layer
Flooring
sandpaper belts
36
aggressive; use on first pass if boards cupped, uneven
(top veneer layer)
Tongue
nail
for large floor
sander; disks for
36 open coat use on first pass if floors coated with wax, paint
edger
60
try for first pass; switch to 36 if not enough cut
100
Second or third pass
buffer screen
100
Final screen before applying finish
(use with
220
Smooth between coats of finish
Flooring
backer pad)
Subfloor
nail
sandpaper strips
180
Smooth between coats of oil-based finish
You can sand only the top veneer layer of engineered
(attach to buffer
backer pad)
220
Smooth between coats of water-based finish
flooring. Solid-wood, tongue-and-groove (T&G)
flooring is a lot thicker, but you can sand only to
the top of its tongue. If you sand lower, you’ll hit
flooring nails. T&G nail heads should be just flush,
* Consult finish manufacturer’s specs for sanding requirements.
as shown.
Flooring
563
Worth a look: The U-Sand®, a four-headed
be used within 6 in. of walls.) Edgers may be
P R O T I P
random-orbit floor sander, comes highly recom-
smaller than floor sanders, but they can still
mended by Charles Peterson, a hardwood floor-
gouge flooring quickly. So practice on plywood.
When sanding floors, follow
ing expert and a consultant for the National
The edger’s paper is held in place against a rub-
the physician’s creed, “First, do
Wood Flooring Association. Peterson notes that
ber disk by a washered nut. To prevent gouging
no harm.” it can take hours to
the U-Sand “is aggressive enough to take down
the floor with the edger, many professionals leave
repair a trough cut by paper
that’s too coarse. in fact, you
floorboards, yet gentle enough for light abrading
three or four used disks beneath the new one,
may have to replace the damaged
between finish coats.” Its orbiting heads are con-
which cushions the cutting edge of the sandpaper
section. So start with the least
figured so that you can sand right up to walls,
somewhat.
aggressive sandpaper grit that
thus eliminating the need to rent an edger. The
A buffer is a versatile tool. With abrasive buffer
will do the job, whether it’s
U-Sand can be rented from Home Depot®, True
screens, it can lightly sand floor finishes you want
removing old finish or leveling
Value®, and other chains.
to restore or fine-sand a floor that you’ve stripped
uneven boards. if that proves too
An edger (disk sander) goes where drum or belt down to bare wood. Its slow, oscillating move-
gentle, you can switch to a more
sanders can’t—along the perimeter of floors and
ment is perfect to scuff-sand between finish
aggressive grit.
into tight nooks. (Large floor sanders should not
coats. Or, when the final coat is down, you can
put a lamb’s wool buffing pad on the buffer to
bring up the sheen of a finish; thus it’s often used
to buff out a new wax coat.
Hand scrapers and sanding blocks reach cor-
ners, flooring under cabinet toekicks, and other
places edgers can’t reach. Hand scraping is
tedious, but it goes more quickly if you periodi-
cally use a fine metal file known as a mill file
(bastard file) to sharpen the scraper blade.
Other hand tools you’ll need include a nail set
to sink nail heads below the surface of the wood
before you begin sanding, a hammer, and wide-
blade spackling knives or metal squeegees to
apply wood filler. If you cut your own edger
disks, you’ll need a pair of heavy scissors.
Brushes and applicators should be matched to
Thanks to orbiting heads in all four corners of the U-Sand sander’s business end, you can sand tight When renting sanders, be sure to get any specialized tools against walls, so there’s no need for an edger. Nor do you need to “sand with the grain” as you must they require, such as the T-wrench needed to change with a drum sander.
sandpaper on this edger.
564 Chapter 20
specific finish types. You’ll find those tools dis-
Buffer screens are held on with
cussed and paired with finishes in “Finishes,
friction. Use them to fine-sand a
Cleaning Solvents, and Applicators” on p. 569.
floor that’s been stripped or to sand
between finish coats.
Personal safety equipment is not optional. Get
a close-fitting respirator with organic vapor fil-
ters. During the sanding phases, wear eye goggles
with side vents; vented goggles admit a bit of
sanding dust, but they won’t cloud up with water
vapor. Drum sanders and edgers are noisy and
tiresome; wearing hearing protection will keep
you alert longer, so you’ll be less likely to gouge
the floor because you’re punchy with fatigue.
Wear disposable plastic gloves when applying fin-
ishes or wood filler. If you can, buy latex-free
nitrile plastic gloves, which auto mechanics, gar-
deners, and postal workers swear by. Nitrile
gloves are tough enough to withstand automotive
solvents and garden grit, yet thin enough to sort
mail with. You can find nitrile gloves at auto
parts stores, typically sold in boxes of 50 to 100
<
br /> in sizes ranging from small to extra-large.
Edging and hand scraping are hard on knees,
so get knee pads comfortable enough to wear
all day.
Rent a heavy-duty vacuum, since there’s no
point in frying a home vac that’s really not up to
the task. Ideally, the vacuum should have a HEPA
filter to capture dust rather than recirculate it
into the room, but not all rental companies carry
them. A backpack vac, shown in the bottom
photo at right is less likely to bash woodwork
and has no wheels to compact sawdust, but
most rental companies offer only wheeled canis-
ter types.
SandPaPEr and BuFFEr SCrEEnS
Sandpaper and buffer screens are rated accord-
ing to the concentration of grit per square inch
and the size of the abrasive particle. The lower
the grit number, the larger, coarser, and more
widely spaced the grit particles. Lower-grit
papers cut more aggressively, whereas the higher
the grit number, the finer and more closely
spaced the grit. Consequently, as you sand floors,
each grit should be slightly finer than the preced-
ing one, smoothing out scratches of the previous
grits, until you arrive at the grit level specified on
the label of your floor finish. Always read the fin-
ish manufacturer’s sanding requirements before
renting equipment and buying sanding material.
If you’re sanding floors to bare wood, you’ll
typically need to make two or three passes with
a large floor sander and an edger and one pass
Backpack vacuums are less likely to gouge flooring or bash woodwork, but
with a buffer with an abrasive screen before
their capacity is generally less than that of floor models. Empty vacuums
when they’re one-third full because the fuller they get, the less efficient
floors are smooth enough to apply finish.
they become.
(Vacuum after each pass.) Get 36-grit, 60-grit,
and 100-grit paper for the floor sander and the
Flooring
565
credit you for unused paper when you return
the equipment.
PrEParing For Sanding
After testing floors to determine the finish, empty
rooms of all movable items (don’t forget window
blinds and shades). Then use 3-mil polyethylene
sheeting to cover the cabinets, radiators, smoke
detectors, doorways, and heating or air-
conditioning openings, using painter’s tape to
avoid pulling paint off the walls and trim. Dust
Renovation 4th Edition Page 130