Date: Sat, 02 Sep 2000 09:19:33 -0700
From: fmoreno4@postoffice.pacbell.net
Subject: Micromesh competition
To: Lancair List <lancair.list@olsusa.com>
Reply-to: fmoreno4@pacbell.net
Reply-to: lancair.list@olsusa.com
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While at OSH I saw a demo in a 3M booth in which they showed their new
plexiglas repair and polish products.  Wonderful stuff.  Starting with a
Bosch (or similar) electrical orbital sander using a foam backed 5 inch
disk, they removed a major set of scratches in about 5 minutes.  You
spray soapy water, sand for a minute with special coarse material, then
go finer and finer (one minute each) and then hand rub with their
finishing compound.  They provide a complete kit on their web site,

www.3m.com/finishingsystems

They also have an aluminum polishing kit that uses WD-40 as a lubricant,
and requires rubbing by hand, but it seems far superior to other buffing
systems I have seen.

I spoke at length to one of the representatives about using their
products for final sanding and buffing of polyurethane paint (including
clear coats) on the planes.  He had just finished doing his personal
Corvette using their products and the orbital sander eliminating a lot
of hand labor.  He used a thick, soft foam pad to support the sandpaper
so he could follow the contours of the body.  His recommendation was to
sand with "3M Imperial Microfinishing Film" using 9 micron grade
equivalent to 1200 US mesh grade (wet sanding), then to to 3 micron,
then final buff with their "Finesse" compound.  They sell sanding disks
with both hook and loop attqchment and sticky attachment.  The stickies
seem to work fine, even on the flexible foam support pats (whch have a
skin of flexible plastic to which the sticky stuff bonds).


A note on abrasives.  Apparently the old US grading system (100, 400,
600 1200 etc.) is based on using particle sizes that are sifted and thus
the abrasive on the sandpaper is actually sized over a range of particle
diameters.  One can buy 1200 grit sandpaper that could have quite a few
individual 600 grit (or larger) particles bonded on the paper.  More
expensive sand paper has narrow size ranges of particles.   The 3M
products for plexiglas are actually formed pyramids on the paper (you
can see them in rows with a magnifying glass) and they are all the same
size so you get very uniform results with no chance of scratching
because of stray big particle on the sand paper.  I tried it, and it is
great stuff.

I bought some of their coarser grades as well (100 micron, 60, 30) and I
have been using them to flatten my prime coats with excellent results.
The sandpaper does not load up, and the orbital sander is the way to
go.  I use long boards in some areas (I did wings exclusively this way)
but for the curves of the fuselage, the results on the primer have been
great.

Fred Moreno

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