RE: Viewports gobbed on with silicon

["Stymer" <stymer@home.com>]

Lexan can also be had with a protective scratch resistant coating called
'marguard'. This coating is made of silicone and therefore the marguard
windows can be sealed with silicone or other such sealant, and they adhere
fabulously, unlike acrylic. In my opinion, acrylic is required for 1 at
subs, but for ambient or wet subs, marguard is the way to go, except for
domes, where acrylic forms much better.




-----Original Message-----
From: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org]On Behalf Of Paul Suds
Sent: Saturday, August 14, 1999 8:17 PM
To: personal_submersibles@psubs.org
Subject: Re: Viewports gobbed on with silicon


OK guys, anyone got a club so we can finish off that horse, Ha. I agree,
that under high pressure (500 psi), cold forming of polycarbonate may be a
problem, but not at the pressures I'm looking at (50psi), especially if it's
1/2 to 3/4 inch thick. Creep is very low. I'm also willing to trade off
scratch resistance for impact strength. We're only comparing Rockwell 70 vs
100 for Poly vs Acrylic, respectively. I've designed products for processing
with injection molding machine using both materials and PETG, but I don't
have the experience that some of you have with view ports. Nothing beats
experience. I might have to revisit Acrylic. I think I'm going to keep this
decision open until latter, which is good. It's great to get this type of
feedback. Thanks for the help.


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