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Just in case any of you have used solvents with Plexiglass, and your
Plexiglass has started crazing (little cracks forming at the cut edges and
spreading out). You can stop it by flame polishing the edges with a propane
torch. You can actually make the cracks disappear permanently if they have
not gotten too deep. This probably anneals the edges of the part like Jim
Cameron was saying. The idea of flame polishing is to melt the surface with
the hottest (blue) part of the flame for a short time so that it flows but
does not burn or boil. Hold the torch at the edge and move it along the
edge at a rate of about 3 inches per second. Try some experimental pieces
first to get the hang of it.
I hate Plexiglass and never use it any more. Everything cracks up
Plexiglass. Isopropyl alcohol will crack it up overnight. Cool Mist
machining coolant will crack it up in about a week. I have used gasoline
once to remove spilled paint, and it seemed to be OK, but I kept it away
from the edges. Windex and Simple Green might work, but I would watch it
carefully and stand by with the torch. Lately I have only been using
polycarbonate commonly referred to as Lexan in my shop, it is much more
chemically durable. I was hoping our windows were not Plexiglass.

Regards,
Ed Armstrong
Watsonville CA.


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