Hints on sanding
and varnishing floors
Until very recently, houses were constructed
with solid wood floors. Since the invention of
the fitted carpet, most people have regarded the
floorboards as nothing more than a platform to
hold the carpet up. This is a shame, because appropriately
prepared natural wood floors look very nice, and
are hard-wearing and easy to clean. That this
is true is obvious from the rise in sales of laminated
flooring systems in the last few years; but why
spend about £1000 per room for laminated
flooring (plus the cost of levelling panels, underlay,
etc) when you you probably have good-quality wooden
floorboards already?
Caution: I only have experience of preparing softwood
floors. If you are fortunate enough to have an
oak floor, you should probably check with an expert
before you attack it with a power sander.
What this article is about
Heavy-duty floor sanders are generally supplied
with instructions, and you can find information
on preparing wood floors in any DIY manual. What
these won't tell you, however, are the problems
you are likely to encounter in a real house, and
how to overcome them. This article is based experiences
over the last couple of years; it is not intended
to provide step-by-step instructions, but simply
to point out the problems you are likely to experience,
and how to overcome them.
Why do it?
If you lift a carpet (and all the other junk that
goes under a carpet) you are likely to see something
like this:
Clearly you aren't going to want to have this
on permanent display. This wooden floor is cursed
with paint spills, undefinable stains, overall
discolouration, and cracks. However, with a bit
of effort (OK, a lot of effort) you can turn it
into this:
It isn't perfect, but it's a lot better, and
I wouldn't be embarrassed to have flooring like
this throughout my house. If you plan the work
carefully, the total cost of turning the first
picture into the second will work out at about
£100 per room. This assumes that you hire
the equipment over a weekend, and you can do two
rooms in that time. It's a lot cheaper than a
laminated overlayed floor, and quicker to do.
Why not to do it
Unless you are lucky, a `real' floor will probably
never look as `perfect' as a laminated flooring
system.
Why?
First, the floorboards are generally
nailed down, often with enormous brads. These
will be visible whatever you do. (However, some
tongue-and-groove floors are held down with small
nails, and these don't look too obstrusive.) Second,
over the years the flooboards shrink, and probably
no longer butt together perfectly. Again, tongue-and-groove
boards aren't subject to this problem to the same
extent. The gaps between boards may be a source
of unwanted ventilation (draughts, in plain language).
Third, if the floorboards have been exposed, but
not varnished, then there will probably be a variation
in colour across the room. Sunlight tends to darken
the wood, so the brighter end of the room will
have darker flooring. Fourth, if the floor is
rotten, holed, infested with woodworm, badly cracked
or very uneven then you will probably never be
able to achieve acceptable results.
A softwood floor will probably always have an
`antique' look to it, however it is treated. It
will probably be knotty, and have a very strong
grain. Of course, many people find this look very
appealing in itself. However, you have some control
over the degree of `antiqueness' of the final
result, as I will explain.
Preparation
For a successful finish, you need to spend at
least as much time in preparation as you do on
the actual sanding and varnishing. This is difficult,
as the preparation takes a long time and does
not give an obvious reward.
It's worth bearing in mind that unless your house
is very modern (in which case it may well not
have wooden floors, anyway) or you are very lucky,
you will find some imperfections in the floor
that make it difficult to achieve a perfect finish,
if not impossible. You need to decide fairly early
in the process how perfect a finish you will strive
for. The more perfect the finish, the more time
you will need to spend in preparation.
First you will need to expose all the floorboards
in the area to be treated. This generally means
emptying the room of all furniture. Although it
is possible to work around a few items of furniture,
it makes the job much more awkward. Moreover,
sanding a floor generates a phenomenal amount
of dust, so you need to make sure that anything
you can't move is well protected from this. In
general, you want to work in an empty room if
it's at all practicable. Naturally you'll need
to remove all traces of carpet, underlay, floor
levelling boards, linoleum, etc.
Second, make good any gross defects in the floor.
By this I mean, for example, replace or repair
broken or loose flooboards. If you do have to
replace floorboards, remember that the new floorboards
will almost certainly have a different colour
to the old ones (unless you take them from another
part of the house). This is particularly apparent
with pine, which goes from a pale, straw yellow
colour to a deep golden yellow over the years.
If you are putting new boards next to old ones,
then you should consider staining the new boards
to match the old. You can get `antiqueing' stains
for pine. It's probably best not to try to get
an exact match for the colour of the old boards,
as the colour you end up with will be a combination
of the colour of the stain and the colour of the
new boards. That is, it won't necessarily be the
same as the colour on the tin. I would suggest
getting a light stain, and applying enough coats
to bring the colours into agreement gradually.
It's best not to stain new boards until after
sanding, as sanding will change the colour completely.
The same logic applies to the use of wood filler
for holes and cracks; you can get wood filler
in a variety of colours, but sand the floor first
to find the proper colour to use.
If some of the floorboards have lifted from their
joists, then you'll need to find a way to fasten
them back down (you might need to use screws for
this, rather than nails). If you don't they will
stop the sander getting to adjacent boards.
At this stage any problems with wordworm or rot
will come to light. Naturally, active woodworm
needs urgent, specialist attention, as does any
sign of dry rot. Wood that is riddled with woodworm,
even if inactive, looks ghastly and, in my opinion,
is best replaced. The same applies to wood blackened
by old, persistent wet rot.
Third -- and this is the really dull bit -- you
will need to ensure that the floor is totally
smooth. Although the instructions supplied with
the floor sander will undoubtedly say that you
should remove or hammer down all nails and screws
in the floorboards, they don't stress just how
important this is. Trust me on this; if the sanding
belt hits a nail that protrudes above the surface
by more than about a millimetre, the belt will
be destroyed. As each sanding belt costs about
£10, you don't want this to happen very
often. In practice this means getting on your
hands and knees, and inspecting the floor in minute
detail. Protruding nails should be given a good
whack with a club hammer; in my experience it
isn't necessary to punch them below the surface
(but don't blame me if your sander is more flakey
than mine).
Sanding
In my area, it costs about £100 to hire
a floor sander and edge sander for a weekend.
If your rooms are completely empty, then you ought
to be able to do two good-sized rooms in that
time. A floor sander is extremely heavy, and if
you're picking one up in a car you might need
help to get it in and out. Similarly, carrying
one up stairs is not a job you want to do too
often.
In short, you need to have your floors fully prepared
by the time you pick up the machinery, and be
able to work methodically. If you have to keep
stopping to hammer down floorboards, or replace
the sanding belt, you won't end up getting good
value for money.
If you haven't heard a floor sander in action,
you'll be appalled by the amount of noise it makes.
If you've ever driven or walked around the perimeter
road at Heathrow Airport when a jet aeroplane
goes overhead, you'll have an idea of the sound
volume to expect. This has two implications. First,
you will need ear protection (I'll admit to being
a bit cavalier about ear protection; I don't normally
bother for things like drilling and grinding,
but five seconds with a floor sander was as much
as my ears could stand).
Second, you might like
to consider arranging the job for when your neighbours
are away. Or buying them a present. It's really,
really loud.
In ideal circumstances a floor sander can be operated
along the length of the floorboards, and two or
three passes is all you'll need. In practice,
most floors aren't in good enough condition for
this, and you will need to sand diagonally or
across the boards as well. If you are working
in a narrow hall or corridor, you may be limited
in the direction you can work. If the floorboards
are uneven (that is, adjacent floorboards have
slightly different heights) you wont get away
with only length-wise sanding, because the higher
boards will prevent the belt getting to the lower
ones. In this case, you will probably need to
work diagonally.
For rapid progress you will probably want to use
a coarse sanding belt. However, a coarse belt
will almost certainly score the wood, and give
it a new grain in whatever direction the sander
is run, so you'll need to use a finer belt as
well after the coarse one. In my experience, if
the boards are level enough that they can be sanded
along their lengths, you only need the coarse
belt (this is a floor, after all, not a table-top).
A floor sander won't reach right up to the edges
of the room; the best it will manage is a gap
of a few inches. This is where the edge sander
comes in. An edge sander is a very heavy rotary
sander, usually with a pair of handles on top.
It will sand right up to the edge of the floor.
The manufacturer's instructions will probably
say that you should run the sander from side to
side, following the wall. It may well have little
wheels to make this possible. Where this means
working along the length of the flooboards this
is quite straightforward. Where this is across
the flooboards, it might not be so easy. If your
floorboards are not perfectly level, you'll find
that the sander won't run evenly from side to
side, and will snag on the edges of the floorboards.
This will make a horrible mess: disk-shaped scars
in the boards. In these circumstances, it may
be better to move the sander from side to side
in small (half-inch) steps, dropping it down onto
the floor for a few seconds at each step. In some
cases I have had to dispense with the edge sander
altogether, and finish off with a hand-held belt
sander. This takes ages, but won't scar the floor.
I'd suggest practicing with the edge sander on
part of the floor that won't be visible, if possible.
In old houses, the floorboards may be warped,
in any direction. In my house, the edges of each
floorboard are about a millimetre higher than
the middles. This means that the sander does not
easily reach the middles, and leads to an appearance
like this:
The middle of each board is darker, because the
sander can't really get there. If you can't live
with this appearance, then you'll need to resign
yourself to sanding away several millimetres over
the whole floor. Small areas of severe warping
can be takled using a hand sander when the rest
of the floor is done.
Wait
Sanding a floor generates a lot of dust (but see
update below...). This dust will remain in the
air for several days. I'm assuming that you're
going to want to varnish the floor after sanding;
you probably don't want dust settling in the wet
varnish. Ideally you should wait at least a day
between sanding and varnishing.
Varnishing
Varnishing a floor is not like varnishing an ornamental
table-top: a bit of uneveness is not going to
be noticed. Therefore there's no reason to use
brushes, or even rollers, for the bulk of the
floor. A floor mop will do just as well, and be
much quicker. If you're using a roller, you'll
need to fit a long handle on it so you can work
standing up. This is for two reasons. First, it
will avoid wear and tear on your knees and back.
Second, you really don't want to get your nose
near floor varnish any more than you really have
to.
For a floor you need a really tough varnish. I
use Rustin's because it dries very quickly, but
there are several brands of specialist floor varnish
available. All have in common that they are extremely
volatile, and disagreeable to use. Rustin's makes
my eyes and nose burn, which can't be a good sign.
I'm not sure how dangerous it really is, but I'd
be inclined to make sure that there are no pregnant
women or small children around. On a warm day,
Rustin's is dry to the touch in about 15 minutes,
and can be recoated in an hour, so you can apply
three coats in one morning. The quick drying properties
also mean that any dust that is still settling
from the air is more likely to land on a dry patch,
rather than getting stuck in wet varnish. A good
floor varnish should not scratch if you drag heavy
furniture on it, but you'll need at least three
coats to get that kind of durability.
Hints
An edge sander will grind through radiator pipes
if you're not careful. Consider covering the pipes
with something while sanding around them.
Hire companies will often supply sanding belts
and disks on a `sale or return' basis. This means
that if you use them, you pay, but if you don't
you can give them back. Unless the hire shop is
very close to your house, you should take as many
belts and disks on sale or return as they will
let you have; it is very inconvenient to run out
in the middle of the job.
If your floor was carpeted, then exposing the
floorboards means in effect that you are lowering
the floor by a half-inch or so. The result is
to make all your doors about a half-inch too short.
Also, if you've got exposed floorboards next to
a carpeted roon, you need some method of finishing
off the exposed edge of the carpet. You can buy
brass or steel edgeing strips for this. If you
don't finish off the carpet edge, people will
catch their feet on it, and it will get scruffy.
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