Are you thinking about refinishing your own hardwood floors? If you are up for the
task it is a great way to save money and take pride in your own home. However, great
results also require the proper amount of knowledge, skill and preparation. Refinishing
a wood floor is a very labor intensive process and there is a process that one must
follow in order to get desirable results. One needs to be prepared for the task before
committing to the cost of refinishing hardwood floors. Are you up for it? If so,
let’s review some of the basics about how to refinish a hardwood floor.
The Refinishing Process
The process I follow to refinish a floor is to strip off the old finish with a drum
sander and an edger using the highest grit sand paper that will do the job effectively
and efficiently. Most often I have to start with a 24 grit sand paper anyway, but
this results in removing a little more wood and require more steps in sanding to
get to a nice, smooth finish on the hardwood floor. However, if a 36 grit sand paper
will do the initial job of stripping off the old finish just as well, I'm going to
start with that. Doing so will save time, money, and serve to preserve the floors
a little longer as 24 grit is very aggressive and every little bit of wood that is
not lost to the sanding process is a little more wood left for future refinishing.
Then I sand as necessary using orbital and random orbit sanders to get to a nice
looking surface on the now bare wood floor. Typically sanding to 100 grit is sufficient
for a natural, clear finish. If a stain is desired if necessary I will sand to 120
grit to get the best surface for a great looking stained finish. Before applying
the stain the floor must be carefully examined for irregular sanding marks. These
marks are more easily concealed under a clear finish, but a stain will highlight
the heck out them. I mark all of the erratic sanding scratches I find with white
chalk and then go back and sand them out. If I still happen to miss one and find
one while I'm applying the stain, then I fan out the staining line so that there
isn't a distinct stop/start line, and I get out my hand held random orbital sander
and sand it out immediately and quickly. Then back to staining fanning into the stain
where I left off. Lastly, a custom stain will add at least a day to the entire refinishing
job because there is a process to follow that cannot be rushed.
Applying A Clear Coat Finish
There are two basic choices in clear coat finishes. An oil based polyurethane or
a water based poly. Both are great looking, durable finishes with some differences
in personal preference and in the application process.
Water based poly is chemically different than polyurethane, but performs the same
function in providing a clear coat, protective finish. The advantages of using it
is that it is low odor, cures faster and can handle light foot traffic sooner after
the last coat than a polyurethane finish. The trade off is that it does not impart
any color to the hardwood floor - such as the common amber tone that results from
using the oil based polyurethane. Therefore, to impart that amber tone to the floor
I apply a coat of de-waxed shellac. Shellac not only imparts the nice amber tone
to the hardwood floor, but it is also a great medium that can actually improve the
bond between the bare wood and the clear coat finish. Most seal coats at the home
centers are made of 100% de-waxed shellac - look at the ingredients, or look up the
Polyurethane is an oil based finish that will impart an amber tone to the hardwood
floor with the first coat and without the need for shellac. In my personal opinion
it does look a little better than the shellac and water based poly finish and, of
course, your opinion may differ. The trade off is that it is very high in a petroleum
odor that lingers for up to two weeks as the finish cures (dries - so to speak).
Current requirements have the VOC in these polyurethanes for floors down to 350 and
even 250. It's high in viscosity and I find that comparatively difficult to apply.
Additionally, as oil based product it requires a little more time before it can handle
light foot traffic. Some argue that an oil based polyurethane finish is more durable.
However, from my research and in my experience I have found that the difference between
using oil based and water based clear coats on floors is negligible - if there is
any real difference at all. Another difference is that while most water based finishes
will fully cure in about a week, an oil based finish can take 2-4 weeks to fully
cure. Lastly, even at the low VOC levels it still stinks pretty awful - in my opinion.
For a clear, natural finish on a hardwood floor, a polyurethane finish can be applied
right away. The first coat will seal the wood and dry enough in about 4 hours that
a second coat can be applied. Typically a third coat should not be applied until
the following day. Before applying a third coat the floor needs to be lightly sanded
to smooth out any nibs from the first two coats and provide for improved bonding
between the second and third coats. Polyurethane is very high in odor and requires
using a charcoal filtered face mask throughout the entire finishing process. Additionally
a polyurethane floor should be left undisturbed for up to 24 hours after the last
coat of finish. A high quality, water based finish will cost more per gallon, but
most only require two coats and both can be applied in the same day - saving time,
if not money too, over all.
Whether you choose a water based or an oil based poly finish the furniture should
have some padding under the feet for the first two weeks. Throw rugs should not be
placed back over the refinished hardwood floor for 2-3 weeks following a water based
poly finish and up to 3-4 weeks following an oil based polyurethane finish. The reason
for this is because these finishes do not actually dry, they cure. Curing is a process
by which the solvents and chemicals evaporate from the finish over time leaving behind
the hard, clear coat finish. If a throw rug is placed over it it could retard this
curing process and have undesirable results. Some may argue that the floors should
be ready for carpets sooner. Perhaps one may get lucky and a throw rug might not
affect the curing process. However, after going through time and expense of refinishing
your hardwood floors why take the chance for the sake of a few weeks with a throw
rug? Lastly, wearing shoes while walking on the newly refinished, hardwood floor
during this curing process is strongly discouraged.
So, which to use? An oil based or water based finish? Of course as the customer you
are the boss. You tell me which one you want on your floors. However, when it comes
to refinishing a hardwood floor I prefer to use the water based finish as it is low
odor, the finishing process is a little faster, and the finish can handle light foot
traffic within 12 hours of the last coat. Alternatively you may opt for an oil based
polyurethane finish. This is also a great looking and durable finish for a floor.
However, I won't use it in a multi-unit building, or if the customer is planning
on staying in the house during the refinishing process. The odor will travel throughout
the structure and can cause personal discomfort to the occupants.
Skim and Recoat
A hardwood floor does not always need to be stripped down to bare wood to get a nice
looking finish. In fact, unless the older finish is severely damaged or there is
some other mitigating reason, stripping off the old finish not only may be unnecessary,
but will shorten the life of the hardwood floor! This is because every time the hardwood
floor is completely stripped of the old finish a little more wood is removed. Eventually
the hardwood floor planks are too thin and will need to be replaced. Therefore it
may be more desirable to do a skim and recoat. Depending on the condition of the
old clear coat, this may not be possible with a stained floor as the process may
affect the original stain. A skim and recoat is simply sanding the old finish with
a random orbit sander to 120 grit. Then a coat of shellac is applied because it is
a good medium that improves adhesion between what is left of the old finish and the
new finish that will be applied. After the coat of shellac is applied the application
of the new clear coat is the same as when doing a complete strip of the old finish.
The result is a great looking floor.
To remove toe mold or to not remove?
Removing the toe mold before sanding the floor is an optional process. The advantage
is that the floor is sanded and refinished all the way to the base trim or to the
wall if there is no base trim. The disadvantage is that this is extra labor and thus
incurs additional charges. It may also necessitate repainting, repairing or even
replacing the toe mold. In either case, even with due diligence to protect the base
mold and toe mold, the process of floor refinishing sometimes nicks the paint on
the base trim and so you should be prepared to touch up the base trim afterwards.
Your home may be the greatest asset you own, so the appearance and protection that
a hardwood floor finish provides is important to you.
Refinishing floors is a labor intensive process and needs to be done right for the
best looking results. There is a lot of buzz out there about being green and using
low VOC compliant polyurethanes. These are good things, but I'm willing to take the
time to inform you what these really mean.