[Public-list] thickness of large portlights

[Hugh McCormack]

I believe that polycarbonate is more resistant to point impact loads than 
acrylic.  That may be a function of its pliability.  Also, polycarbonate is 
stronger than acrylic for a given thickness.  Finally, polycarbonate tends 
to be more expensive, at least here in Canada, than acrylic (not that this 
should matter for the amount of material in an Alberg portlight).

Hugh McCormack



>"Lexan" is GE's proprietary name for generic polycarbonate. Plexiglass is 
>an acrylic. Acrylics are >initially soft and pliable due to the 
>plasticizers that they are made with; the UV will eventually >degrade the 
>plasticizers and therefore the acrylic (Plexiglass) and make them brittle. 
>Polycarbonate >(Lexan) is originally pliable and will retain this 
>pliability for many years; it is much more UV resistant. >Polycarbonate 
>will also expand and contract much more than acrylic.

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