Ė SECRETS TO SUCCESS
Understand what your finish system requires. You have to approach
sanding from the perspective of the finish and not your finger. Of
course you sand to level joints and smooth the surface; however you
are also providing a uniform texture that will help take stains
evenly and provide a tooth for the finish to grab on to. Selecting
the correct grit and type of
paper are crucial. Many of the high solids finishes require less
white wood sanding than their older counterparts. Over-sanding is
not only counterproductive, but it will ultimately encourage
To reduce clogging, wood should be sanded with an open coat paper;
finishes sand best with a stearated paper. Wood sands best with an
aluminum oxide paper since the particles fracture during use and
constantly expose sharp new edges. For finishes, silicon carbide
paper is the choice when sanding finishes by hand; a high quality
aluminum oxide paper works best when
machine sanding a finish.
Abranet discs are excellent for sanding sealers and primers as they
donít clog under these high load situations.
Micron graded sandpaper has the most uniform grit size and makes it
the best choice when machine sanding finishes or solid surface
Abralon pads are used wet for repairing or polishing a finish.
Mirlon pads work well for scuff sanding washcoats and toner coats.
Neither of these two products will level a finish, for that you need
a cloth or paper backed abrasive.
Sanded with 120
Sanded with 220
Sanded with 120
Sanded with 220
When sanding finishes, be
sure to let the finish dry sufficiently before sanding, but donít
wait too long. The process of spraying a coat of finish, sanding it
and then applying the next coat should optimally take place within a
24 hour period. This is very important when using any type of
catalyzed finish since they do not melt into the previous coat. All
catalyzed finishes bond to the previous layer by a mechanical link;
they need a rough surface to adhere to, so sanding between coats is
essential. The goal is to sand and apply the next coat before the
previous coat of finish is totally shrunk; this way the new coat is
deposited in the sanding scratches of the first coat which will then
shrink around the new coat and give you maximum inter-coat adhesion.
How course of a grit we
need to sand with depends on how thick of a film we applied, how
smooth and uniform the film is, and how old the film is. Sand with
only as course a grit as necessary to level the surface. Remember
fresh finishes will continue to shrink back after you sand them,
cured finishes wonít. Sand a fresh finish with a 220 grit and you
can recoat with no problem. If you have to sand a cured finish with
220 your sanding scratches might telegraph thru the next coat
because the finish will no longer shrink back around the scratch. In
this situation its best to follow the 220 with a 320 grit paper.
In sanding we try to
scratch an ďeven textureĒ onto the wood. This will help us obtain an
even color when we stain. Your sander or hand block should have a
soft pad. A hard pad may cut faster, but a soft pad will compensate
for minor surface irregularities and will allow a more consistent
contact of the grit with the surface it is sanding.
If you sand
by hand, you should duplicate your style and movements consistently
from piece to piece, edge to edge.
If you spot
sand by hand use at least one grit finer than the last grit you used
on the mach
When using a
sander, let the weight of the machine do the work, this will do much
to insure a consistent depth of scratch from piece to piece.
on your sandpaper wear down or break off as they are used. A worn
out 120 grit belt will polish a board smoother than a 400 grit belt.
By replacing sandpaper or belts before they get too worn you will
maintain a more consistent scratch pattern and depth.
HARDWOOD LUMBER AND VENEER
Sand bare wood with an open coat aluminum oxide paper, silicone
carbide is too sharp.
no higher than a 150 grit.
one grit higher than lumber; but no higher than a 180 grit.
progression of grits. Skipping a grit may cause uneven staining or
even scratches to telegraph thru your topcoats.
The finish film shrinks as it dries. Sharp edges will rip the film
and allow water and oil to eventually get in. Think of it as
stretching a piece of Plastic Wrap over a knife blade.
The day that you
sand your wood is the day that you should stain and seal it.
should be sanded with a 320 paper.
MDF edges and
profiles should be sanded with only 400 and 600 grit sandpaper. A
course paper tends to pull out the wood fibers from the binder in
the MDF, resulting in more pits in the surface. Use a course paper
only when necessary.
SANDING BETWEEN COATS OF FINISH
be recoated within 8 hours of being sanded.
between coats of finish use a 220-320 stearated paper.
silicone carbide paper if sanding by hand, a high quality aluminum
oxide paper like Royal Micro if using a machine.
usually the maroon, or a 320 paper are good for scuffing toner and
washcoats. Mirlon scuffs, but it wonít level.
Steel Wool as it may contain oil and the fibers are hard to clean
thruís. Give a burn thru extra drying time before recoating. This
will reduce the chance of wrinkling.
If you are
going to glaze, remember that the glaze will stick in your sanding
scratches so sand carefully.
sanding, to avoid deep localized scratches use at least one grit
finer than the last grit you used on the machine.
sanding dust before recoating. Take extra care to get it out of the
pores of woods like oak.
A word about swirl marks. If you have them, then there is a problem
with your sander, your system or the person using it. A few simple
precautions and you can all but eliminate them from your life.
Start with a
good quality, adequately powered and maintained machine.
If you are
using pneumatic sanders, check your plumbing. Be aware that the
length and size of piping and hose will affect performance. A common
culprit is the use of reducers to go in and out of improperly sized
filters or regulators. Start at your compressor and look your way to
equipment. Inspect, Clean, Lubricate, Repair, Replace. Nothing lasts
and bearings. Flat pads and smooth bearings; itís a good thing.
technique. Let the tool do the work. If you slow it down, it will
sanding schedule. Donít
make big jumps between grits. Skip steps and it will swirl.
paper. Keep it sharp. Micron graded paper will swirl less than CAMI
or P graded papers.
moisture content of your wood. If itís wet, it will swirl.
instincts. If it doesn't look, feel or sound right, it will swirl.