From: John De Armond
Subject: Re: Class C Cabover Window
Date: Sat, 08 Apr 2000 21:28:24 EDT
Newsgroups: rec.outdoors.rv-travel

Greg Harvey wrote:
> 
> Thanks for the pricing info, Will. Do you know where I can find contact
> info for BOEING SURPLUS? Thanks,
> 

For a number of reasons I'd a thousand times rather have tempered
glass as Lexan or any other plastic glazing.  Among them

1.	Polycarbonate is rapidly deteriorated by environmental
contaminates and hydrocarbons.  A few drops of gasoline will cause
polycarb to craze like crazy.  Hit it with some superglue
accelerator and it will crumble in your hands, something apparently
a lot of kiddie vandals know.  The polycarb we use in the sign biz
is laminated with an outer layer of chemical and sunlight-resistant
material.  Unfortunately that material is also soft so the benefits
of polycarb's scratch-resistance is lost.  Acrylic sheeting is soft,
not very rigid (so it bows in and out as the air pressure in the MH
changes) and tends to yellow in the sunlight, as well as being
susceptible to damage by a wide variety of common chemicals.

2. 	Polycarb is too strong.  DOT correctly bans it for use by OEMs
in front windows (which your cab-over window would be).  it is
banned because it is so strong that it causes neck and head injury
in an accident.  

3.	when it does break, it leaves sharp splinters that are in many
ways, more destructive than glass shards.  Whereas if your head goes
through a glass window, many of the shards break away.  Plastic
bends and so many shards remain attached to the window to form a
trapdoor around your neck.  As you recoil from the wreck's impact,
the shards stab into your neck.

4.	It is more expensive than glass.

The proper glass is laminated safety glass.  Not that hard to get
custom-cut.  The next best choice is tempered safety glass. It too,
shares the property of being too strong but at least when it does
break, it shatters into dull particles.  One mitigating technique is
to have the window made out of single strength glass which is very
thin and even when tempered, not that strong.

The previous owner of my MH replaced one side window with polycarb. 
Guess which one rattles, bows in and out and stands out like a sore
thumb from all the tree branch scratches?

John