The basic concept for fairing
is to build up multiple layers of various primers, "Block sanding" between
each application with a long board that will bridge the low spots and only
remove material from the high spots. I switch colors of primer and
repeat this process until I see most of that color disappearing one high
spots. There is a technique for doing this effectively. I do what is called
a "cross hatch pattern". I choose an area that is easy to work from where
ever I am standing or sitting. Lets say I choose a part of the hull that my
arms can reach and I am still comfortable. I envision a square area and I
start sanding with the board at 45 degree angles until I have sanded the
entire selected area. I then switch to the opposite 45 degree angle and
repeat what I did in the first step, going right over the previously sanded
watch carefully to see if any of the previous surface starts to show thru.
If so, that indicates a high spot and if I am threw to that surface I can
then see the low spots around that the sandpaper never touch. This is the
first sanding on that coat of primer.
If I still have enough primer in my little square, I turn the board up and
into a vertical position and sand the entire area with vertical strokes.
Next I turn the board back to horizontal and I sand at a 90 degree angle to
the previous direction.
The purpose for changing all of these directions, is to prevent my sanding
from doing exactly what caused the dimples in the first place. They are
generally caused by someone sanding the surface before with a round sander
and tipping the edge of the pad up at about 45 degrees. Ultimately digging a
hole in the surface.
a rule when I have this much thickness to sand, I start with 89 grit. This
makes the work go a lot faster and doesn't require so much labor.
I'll continue this coating and sanding with 80 grit until I feel I have
created a surface that will work for me.
my last coats of white 545 I sand it with 180 grit to eliminate the 80 grit
marks that may still be visible.
Sometimes when I finish with the 180 grit I may need to spray one more, thin
coat just to fill-in the 180 grit marks.
Now on this last coat I spray white (if I am painting the boat something
close to white) and then I sand by hand careful not to sand thru to one of
the other colors.
Now the surface is ready to paint.
With Awlgrip I spray the first coat with a fair amount of reducer. This
first coat is so thin that it hardly puts a shine over the primer. I wait 45
minutes and spray another coat that isn't reduced as much as the first coat.
Wait 45 minutes and spray another coat that is mixed exactly like number two
Now after 45 minutes I need to inspect the surface carefully and decide
whether I want to add a fourth coat.
Usually, the third coat is enough.
TIP: If you are good at spray painting you can substitute the Spray
Converter with the Brush Converter. It slows the initial cure process a
little and allows the paint to flow out better.
Over the next 15 to 20 days you will notice that the finish changes during
this cure time.
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