I manufacture Transparencies for a living.
Mostly windshields for sports cars. There are so
many places to screw up that it can be a truly
humbling experience. What puzzles me is that
most folks give little atention to the canopy as
it ages. You can double the life of a canopy
by keeping it squeaky clean and polishing the
surfaces at least annually. Proper polishing
doesn't remove material from the plastic, it removes crap
from the plastic. Micromesh is NOT a polishing system
it is much too agressive, it is for repair work. Even
with normal care, the exterior (interior also) will eventually
degrade and start to produce chalk like deposits as the
monomers in the plastic sublimate. Once it gets to this
state, you basically are on life support. If you have
a canopy that is so old it just won't polish well,
Micromesh probably won't help as the sublimation is
in most cases deeper than the max grind depth of the system.
When you get to this place, toss the book aside, and get a bit creative.
The object of the game is now to stop sublimation and seal the canopy
surface with something you can see thru. Believe it or not, the
green can TURTLE WAX will make things a lot better. It
will fill the small scratches and surface pores and get you back
to a usable canopy surface. The downside is that it stops the canopys
ability to breathe and adjust to humidity changes which will cause
a higher internal hoop stress load to exist and make the canopy less
forgiving to bumps and racking. DON'T do this to a canopy with
life left in it, but when the choice is this or a replacement, I like doing
this first.
I've got some vintage race cars going on 5 or 6 years doing this. They
are one step from the grave as far as repairability, but they still work ok
enough to use. As far as day to day maintenance, a couple thoughts.
First, Plexiglass (PMMA) isn't really a solid. It is an incredibly viscous
liquid and is pourous. This means that the stuff it is made of can
"evaporate"
(sublimate) over time. It also means that stuff you put on it can "go into
suspension" inside the plastic. This is why I cringe so bad when I see
Lemon Pledge used on a canopy. Not only is the propellant, usually
isobutane, (a great solvent I might add) trapped inside the canopy by the
wax
so it can disolve the internal structure of the plastic, but the free
breathing of
the plastic and its ability to adjust its relative humidity are compromised.
Dust can do the same thing, it will plug the plastic pores and in most cases
it is acidic and will react adversely to the plastic. So what to do.
Keep a piece of dry flannel on the canopy when you aren't using it. Only
use good quality plastic cleaners designed for the plastic you have. Always
start a canopy cleaning with clear water to get the dust off the canopy
before you start smushing it into the plastic with your cleaning rag.
Only use soft cotton to clean the canopy, old diapers are the gold
standard. I hope this helps, and no, I'm not looking for canopy work....

Scott.