Here is a run through on my finish:
After the plexi is dissolved I pour it into a clear
condiment bottle (Wal-Mart $.79, but any container
that allows you do dispense a drop will work - though
you should check to make sure the acetone won't
dissolve the bottle) and add a bit more
acetone until the solution is a bit thicker than thin
CA glue. I check mine by putting a drop on a paper
towel, the drop should retain its shape for just a second
before being absorbed.You can experiment to get your ideal
viscosity, some people like the solution much thicker
than mine.
I sand my blanks to 400 grit and then remove all of
the dust from them. I lay newspaper across my lathe,
under the mandrel and set the lathe at 1800 rpm, I
also have a spacer bushing at each end of the mandrel.
I put a small bag from a pen kit and put it over my
index finger, fold a 1/2 paper towel to about 1/2 inch
wide.
Put a couple of drops of solution on the paper towel
and run it under the spinning blanks. Start applying
just a little pressure on the bushing set before the
blank and make a smooth motion through the bushing at
the opposite end (the motion should take about as long
as it takes to say "motion.") Then put another drop on
the towel and go the opposite way, use enough solution
so that the towel is transferring the solution to the
blanks through the whole range. I put 40 coats on
in about 3 to 4 minutes (drip, slide, drip, slide) it
dries quickly enough that the time it takes to add a
drip is all the time you need to wait. (Thicker
solutions mean slower drying time.)
After the coats have been applied, I let the lathe
spin for 2-3 minutes and then start wet sanding (just water)
with Micro Mesh. Be careful with the 1500 grit, with my
first few tries I removed most of the plexi with that
one. Just a few seconds with moderate pressure is
enough for each grit, and dry off the blank between
grits to remove the slurry. The MM work is done at the
same 1800 rpms. After some practice the whole
procedure from the first drop to removing the polished
blanks takes about 6 - 7 minutes.
I turn the lathe off and use a utility knife to score
the plexi just a bout 1/16 - 1/8 inch from the end of
the blank, be careful to do it lightly so you don't
cut into your bushings. I learned the hard way to
score, since the finish is built up on the bushings as
well as the blanks. I then remove the blanks and trim
any extra finish off the ends. I put a small piece of 400
grit sandpaper on the lathe bed and rub the finished ends
of the barrels (holding them perpendicular to the bed) to clean
off any extra finish that might extend from the ends.
