From: John De Armond
Subject: Re: Diamon-fusion treatment for windshields
Date: Wed, 03 Nov 2004 02:22:42 -0500
On Wed, 03 Nov 2004 02:46:56 GMT, Camille Pronovost
>A friend of mine recently purchased a motorhome and the dealer sold her
>a treatment for the windshield called "Diamon-Fusion". Rain just beads
>up and falls away. Also, glass supposedly becomes more resistant to
>chips and cracks. It is supposed to be a permanent coating as it makes
>chemical changes in the glass surface at the molecular level, according
>to their web site:
>It was fairly expensive (several hundred $$ IIRC). Has anyone here had
>Diamon-Fusion applied to their motorhome windshield? If so, any comments
>pro or con?
No, but I can glean enough facts from their web site and the patent
(#6,245,387) to make my BS detector go on full alert.
This process of coating glass with a dimethyl siloxane (DMS, silicone
rubber) film has nothing to do with diamonds (thin film deposition of
actual diamond is now a common industrial process), nor does it have
anything to do with fusion. There are two strikes. And it has nothing to
do with nanotechnology. Strike three, yer out. But let's keep going.
From here on out, this disclaimer applies: I'm only an amateur chemist.
A very motivated one but an amateur nontheless. I have amateur experience
with thin film coating but I'm not an expert.
The chemical bonding of a thin DMS film is old news. This is one of the
films that is applied to eyeglasses to make them fog-resistant and
hydrophobic (sheds water).
The process involves something called CVD or chemical vapor deposition.
This involves putting the object to be coated in a chamber into which the
siloxane monomer is introduced as a vapor. An energy source such as a
plasma, intense UV light or even nuclear radiation is used to a) cause the
monomer to polymerize and b) chemically clean the glass (or plastic)
substrate down to the molecular level so that there will be active bonding
sites for the DMS to bond to.
This is described in their patent as method A. Photos on the web site
appear to show UV reaction chambers.
As they show in the patent, the DMS is a long molecule, ideally oriented
perpendicular to the coated surface. Even though the base molecule of the
chain is chemically bonded to the glass, the long chain is fragile (we all
know how easily RTV silicone tears) and can be worn away easily. That's
why we don't use abrasive wipers such as paper towels on our coated
The chain may end in an OH radical. This radical will bond with other
substances such as oil, dirt, the rubber from the wiper blade, etc to both
discolor it and cause rapid wear. They address this (also old technology)
by capping the DMS with a chemical that will bond to the OH radicals and
render them inert.
This is all good and conventional stuff and the product would be wonderful
if your windshield was placed in a CVD chamber and coated properly AND
compatible windshield wiper rubber was fitted. But it isn't. Method B in
their patent is a "smear on, wipe off" coating method. Unfortunately
AFAIK, there is no know method for this to actually work. The surface of
the glass, even after thorough cleaning - even with acid - is still
cotaminated with a wide variety of substances, ranging from one or two
molecule thick oil films to air molecules. These substances "clog up" the
glass surface and interfere with the chemical bonding of the DMS. The is
the reason that the first step in CVD is active cleaning using plasmas,
ion beams, UV and even H2/O2 flames.
I have done aluminum deposition onto telescope mirrors and sapphire
(aluminum oxide) onto glass in my homemade chambers so I have some
experience in this area. In both cases, cleaning the glass properly is
THE most tedious and important step. I used microwave generated Ar/O2
plasmas in a partial vacuum in a homemade chamber (read: microwave oven
magnetron antenna inserted into a modified pressure cooker) to generate my
cleaning plasma. The chamber had to be flushed of oxygen before turning
off the plasma or the surface would become contaminated with molecular
oxygen again. Obviously, they're not doing this with their
My guess is that this stuff will be quite similar to Rain-X (which itself
is a silicone molecule.) It will be effective for a little while and then
hang on as an almost impossible-to-remove nuisance for a long time.
Repeat, this is a guess, but a somewhat educated one.
Just the fraudulent name would be enough to make me run the other way.