The current American Woodworker has an article on making clear router
baseplates. And... I found a large sheet of 1/4" clear plastic at a garage
sale yesterday. So I decided to make a base.
The plastic cut, drilled, and routed very easily, with none of the
brittleness I associate with acrylic; so I figured it must be polycarbonate
(which I have not used before).
The article says to use either acrylic or polycarbonate, and to "flame
As soon as I touched it with the flame, it caught on fire! (actually I
tested it on a piece of scrap first, so nothing was lost...)
So what kinda plastic do I have? If acrylic and polycarb can be flame
finished, then I must have something different?
Without knowing more, I can't tell if it's flammable or inflammable
Seriously, it's probably acrylic. Flame polishing is a tricky business.
Touching the flame to the plastic will very likely ruin it.Here are
some other ideas for smoothing edges:
You probably do have polycarbonate. Try taking a strip of the scrap and
bending it. If it snaps, its acrylic. If it bends, its poly. The stuff burns
well, as you found out. Flame polishing is tricky. Don't actually touch the
flame to the plastic. Just get close.
Don't bother - just sand it with ever finer grits until you get a finish you
If you want it really clear, use a polishing compound. You can use the stuff
that is sold for finishing gelcoat on boats or repairs on cars. For really fine
finish, you can use the finest polishing compounds for glass or metal. A
Dremel with a small buffing wheel can speed things up.
Did the 'fire' continue to burn, after you removed the flame? Or did it
go out after you removed the flame?
In the countertop business, acrylic material won't burn by themselves.
Polyester (which can also be completely clear) will continue to burn
after the starting flame has been removed.
The edge colour, as pointed out by another reader, can give you some
Acrylic, polyester, and polycarbonate all smell different too. Polyester
smells like fibreglass.
Brittleness, is not an indication of acrylic as it is les brittle than
polyester...but I do not know about polycarbonate.
Odds are that 1/4" clear plastic at a garage sale won't be polycarbonate
as it is ghastly expensive.
My bet is that you have a piece of of basic plexiglass. Plexiglas is the
same chemically as Lucite: poly(methyl methACRYLate). Polycarbonate is
Lexan. Another hint is that plexiglass is almost always 1/4".
Polyester is common - Mylar is a brand name and is in sheet
form. Vivak is another brand. Clear plastic pop bottles are a type of
There are lots of other plastics. Polystyrene burns easily - are you sure
it's not polystyrene?
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