Re: [PSUBS-MAILIST] bubbles on dome

["Cliff Redus" <dr_redus@devtex.net>]

Alan,


A quick google search indicates that acrylic can be either hydrophilic (
i.e., strong affinity for water) or hydrophobic (affinity for oils) .  My
guess is that yours is hydrophobic.  You can tell by placing a drop of water
on the viewport and observing if it wants to bead up ( hydrophobic) or smear
out (hydrophilic). If its hydrophobic, then small micro imperfections in the
acrylic viewport will contain very small air bubble that act as nucleation
points for larger air bubbles.   If this is so, (just a guess) then, you
might be able to use a product sold to make rain water sheet on windshields.
This makes the surface, at least for a while, more hydrophilic. Auto supply
stores carry this type of product.  Just a thought.

Cliff



----- Original Message -----
From: "Alan Winick" <subguy33@yahoo.com>
To: <personal_submersibles@psubs.org>
Sent: Thursday, September 26, 2002 5:23 PM
Subject: [PSUBS-MAILIST] bubbles on dome


> OK guys, here's another one to chew on.
>
> I use double bow domes on Explorer. The inner dome is
> flanged to the pressure hull. Covering it is a 3/8"
> free-flooding dome. It's good for impact/scratch
> protection and also protects the inner dome from
> fingerprints and oils from the public when the sub is
> on exhibit.
>
> Anyway, I use Novus plexiglas cleaner/polish to
> maintain both domes. When I submerge, though, a
> stubborn layer of air bubbles adheres to the inner
> dome. Can't reach them to wipe off! Any ideas on how
> to prevent this? I thought of using some sort of
> surfactant, but don't want to damage the acrylic.
>
> Alan
>
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