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Re: Epoxy: Sanding fiberglass and epoxy
By:Rob Macks / Laughing Loon CC&K
Date: 1/9/2008, 8:54 am
In Response To: Epoxy: Sanding fiberglass and epoxy (Shaun)

: I have my strip built kayak all together now, applied the last of the
: fiberglass today on the outside seam. Now I need to sand everything smooth
: and feather the edges of the tape. I was using regular dry sandpaper, and
: it seems to get completely gunked up almost immediately. If I were to keep
: going like this I'd probably use 30 sheets. Is there a better method for
: sanding than this? If I wet sand with water will this eliminate or
: minimize the gunking up of sandpaper?

Are you sanding with a random orbital sander? This is the best power tool
for the job. You need a soft backing pad on the sander. This will allow
the ROS to conform to the curved surfaces on a stripper.

Paper clogging is either using too fine a grit or your surface is uncured
or both, which may be your case.

I sand new resin after a couple days. I feather glass edges and level drips
with my ROS and 60 grit paper.

Most people familiar with woodworking will tell you to use 80 grit because
this is the coarsest paper grit they use. BUT they are only removing machine
marks from flat boards that have had defects and irregularities of the
surface removed by a thickness planer.

Sanding can be understood when you learn it is three different tasks.

Leveling, smoothing and polishing. Leveling is the removal of surface
irregularities, smoothing is removing the scratch marks left by leveling
and polishing is reducing the scratch marks to the desired point for finishing.

The finest grit used for leveling is 60 grit. 60 grit should be used to produce
a flat uniform mat looking surface without low spots.

If you try to level using 80 grit you will have to apply excess pressure and
use an edge of the sander to "erase" irregularities. This will insure an
irregular surface that will not be "fair". And your paper will clog.

60 grit paper on you ROS will cut quickly and cleanly. A random orbital
sander works like no other surfacing tool by riding on the high spots and
utilizes disk speed and disk grit instead of high motor power and tool
weight. The round pad and random stroke will not cut deeply into a surface
as long as the full pad is held FLAT against the work surface. These
features make the random orbital sander ideal for sanding the complex
curves of a stripper.

You cannot know how thick your coatings are over your fiberglass. If you
expect to sand through the grits until you're ready to varnish you are
very likely to sand into the glass. If you sand with the constant worry
you will hit the glass you will not sand enough.

The solution is simple. Rough sand with 60 grit, feather your seams.
Then apply two coats of resin. ONE is not enough. These coats will be very
smooth and look like the boat's varnished. Then sand with 120 and 220 grit
and varnish.

The 60 grit will cut fast and leave a uniform surface. The two coats of
resin will insure you will not cut into the glass. And the resulting
smooth surface will be fast and easy to prepare for varnish.

All the best,
Rob

Messages In This Thread

Epoxy: Sanding fiberglass and epoxy
Shaun -- 1/8/2008, 8:05 pm
Re: Epoxy: Sanding fiberglass and epoxy
Shaun------WebKitFormBoundarydVVq+AkKF+NDgj9d -- 1/12/2008, 11:00 am
Ain't it lovely when you use the correct tool
Paul G. Jacobson -- 1/12/2008, 4:21 pm
Could be blush------WebKitFormBoundary7KwtG0+1jge7
Jay Babina------WebKitFormBoundary7KwtG0+1jge7S+29 -- 1/10/2008, 7:52 am
Re: Epoxy: Sanding fiberglass and epoxy
Aaron -- 1/9/2008, 9:08 pm
Re: Epoxy: Sanding fiberglass and epoxy
Shaun------WebKitFormBoundarydVVq+AkKF+NDgj9d -- 1/9/2008, 7:20 pm
Re: Epoxy: Sanding fiberglass and epoxy
Mike Savage -- 1/9/2008, 10:44 pm
Re: Epoxy: Sanding fiberglass and epoxy
Rob Macks / Laughing Loon CC&K -- 1/9/2008, 8:54 am
Re: Epoxy: Sanding fiberglass and epoxy
Doug Smith -- 1/13/2008, 12:36 pm
Re: Epoxy: Sanding fiberglass and epoxy
Rob Macks / Laughing Loon CC&K -- 1/13/2008, 5:20 pm
Re: Epoxy: Sanding fiberglass and epoxy
Ken F -- 1/9/2008, 8:10 am
Re: Epoxy: Sanding fiberglass and epoxy
Bill Hamm -- 1/13/2008, 1:39 am
Re: Epoxy: Sanding fiberglass and epoxy
Paul G. Jacobson -- 1/8/2008, 9:49 pm
Re: Epoxy: Sanding fiberglass and epoxy
Dave Houser -- 1/8/2008, 9:47 pm
Re: Epoxy: Sanding fiberglass and epoxy
fred Gasper -- 1/8/2008, 9:08 pm
Re: Epoxy: Sanding fiberglass and epoxy------WebKi
Shaun------WebKitFormBoundarydVVq+AkKF+NDgj9d -- 1/8/2008, 9:11 pm
Re: Epoxy: Sanding fiberglass and epoxy
Glen Smith -- 1/8/2008, 8:17 pm
Re: Epoxy: Sanding fiberglass and epoxy
Paula -- 1/14/2008, 12:25 pm
Oops, forgot to mention "Blush"
Glen Smith -- 1/8/2008, 8:30 pm