PerspexVs Polycarbonate

LeonF

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25 Jun 2001
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1,193
Location
South London
Any opinions on the above for windows- they are the surface mounted type. I know the usual pros and cons ie: one scratches less , the other is stronger but is there anyone who has used both at some time and has a marked preference ?

L.A.R.Ferguson
 

jfkal

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Joined
17 Aug 2001
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Singapore
Great stuff as long as:

1. You get the UV resistant type
2. Do not have to bend it to fit
3. Drill holes slightly larger than screw (to allow for expansion).
 

Robin2

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Joined
20 Dec 2001
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Malahide, Ireland
I found polycarbonate very easy to cut with my jigsaw - no chips whatsoever. And from the way the 10' x 4' sheets were handled by the supplier it is incredibly tough and flexible.
 
G

Guest

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I have to agree with jfkal on one of your reply postings. If you need to bend or curve the glazing material to follow the contour of your window or cabin sides then Acrylic Perspex is better. Polycarbonate does not like to be bent. Given time it will crack/craze due to the stress of being bent/curved. Since both materials expand quite a lot (Acrylic more than polycarbonate) when temperatures rise, then it makes sense to allow for this thermal expansion. Screw holes need to be of a larger diameter than the screw shanks. Use a low acetic acid silicon or better still the correct Sikaflex product to seal. Don't tighten the fixing screws down fully untill the bedding seal fillet has cured. (Otherwise you will just squeeze it out.) Once the bedding seal fillet has fully cured (a good 48 hours or more) then go round finally niping the fixing screws up in a similar fashion to tightening up an engine cylinder head, alternate sides to even out the stresses. Don't over tighten and if possible pad each screw with a polythene or nylon washer to allow the acrylic or polycarbonate to creep under the screw head during expansion or compression as temperatures rise or fall. In this way you will maximise the life of the glazing.
Acrylic perspex is quite easy to cut or drill. Just make sure your cutting tools are sharp and don't force the saw or drill through. Use scrap wood to support both sides of the perspex when sawing and use scrap wood to support the exit side of any hole drilling.
Polycarbonate is much better at resisting impact damage than acrylic, this is one of the reasons why safety glasses a made of the stuff. Generally polycarbonate is harder but also more brittle than acrylic. On the other hand acrylic being softer will scratch much easier.

I re-glazed both sides of a Skipper 17 cabin last year (curved profile so used Perspex) and so far it shows no sign of stress fracture or crazing. I used 5 or 6mm thickness. Any thicker and it becomes more difficult to curve.

Hope this helps
An Ron Beag
 
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