From: "Hunter GA (Gary)  at MSXSCC" <GH334766@MSXSCC.shell.com>
Subject: COZY: Cabosil
Date: Mon, 4 Jan 1999 08:28:56 -0600 

> Graham wrote -
> 
< Cabosil is colloidal fumed silica. Cabot Chemical Co?  It's used as a
> thixotropic additive with paints and resins. Mixed with micro in a
> proportion of 1 part by volume (very hard to weigh it, too light) to 5
> or 6 parts of microballoons it alters the viscosity and surface tension
> of the resin in a very favourable way. Resin to balloons ratio is aided
> and the micro spreads easier. Just make sure you don't breathe any into
> your lungs. >
> 
Typically, it only takes about 0.5% wt. of Cab-O-Sil to 'body' up a resin to
a nice creamy consistency that appears to be so much nicer to use than
"Micro".  Do not be tempted by this pleasantry to substitute a portion of
any microballoon mixture with Cab-O-Sil unless you are prepared to pay the
price in weight and elbow grease.  Cab-O-Sil's primary attribute is to
increase the apparent viscosity of the liquid.   (Thixotropy)   Despite it's
appearance (light and fluffy like microballoons), it does not displace any
appreciable volume.    Cab-O-Sil is used extensively in foods like ketchup
and spaghetti sauce, gravy etc.  

Conversely, 0.5% wt. Microballoons in the resin will almost double the
volume, reducing the density of the mixture by about half.   This is the
primary attribute of Microballoons.  Secondarily, it facilitates easier
sanding, and thickens the mixture so it won't run or sag.   The lower the
viscosity of the resin, the more balloons you can add before the mixture
becomes too thick for application.  The more microballoons, the lighter the
mixture, and the easier it sands.  

Thus, by adding Cab-0-Sil to the mixture you increase the viscosity, which
in turn limits the amount of microballoons you can add to the mixture.  This
makes it heavier, and harder to sand.  Not a good deal.   

Gary Hunter

>  

From: cdenk@ix.netcom.com
Date: Mon, 4 Jan 1999 09:37:38 -0600 (CST)
Subject: Re: COZY: Cabosil

After doing filling to contour with micro, I would squuege on a very light (leave only the wet look 
of the epoxy) filling pin holes of 50/50 of micro and cabosil in a slurry (not dry) honey 
consistancy for the last 1 or 2 coats.

From: "terren" <guy.terren@wanadoo.fr>
Subject: COZY: Silica
Date: Sun, 21 Feb 1999 08:21:03 +0100

Hi All,

I've been told by my local supliers that mixing epoxy + microballoons+ a few
parts of SILICA will give a look like gel, which will be very easy to apply.

Wicks catalog told about SILICA to use it with polyester.

Was i told some fairies stories................ Did any one try this or have
an advice on it

Thanks for an answer

GUY

Date: Sun, 21 Feb 1999 07:52:36 -0500
From: Jeff Russell <JRaero@gte.net>
Subject: Re: COZY: Silica



terren wrote:

> Wicks catalog told about SILICA to use it with polyester.
>
> Was i told some fairies stories................ Did any one try this or have
> an advice on it

This is Cab-O-Sil.  Works with epoxy also.  Adds viscosity and makes
it creamy.

--
Jeff Russell/AeroCad Inc.                    E-mail:   Jeff@aerocad.com
2954 Curtis King Blvd.  Ft. Pierce, FL. 34946
Shop# 561-460-8020 7:00am to 3:30pm  Home# 561-344-6200
Website:   http://www.Aerocad.com
Composite workshop info:   http://www.Sportair.com


From: cdenk@ix.netcom.com
Date: Sun, 21 Feb 1999 08:00:32 -0600 (CST)
Subject: Re: COZY: Silica

The material is "Cab-O-Sil". I think it adds weight. I use it only for the 
last coat or 2, after the contour is correct, and just to fill in small 
voids. Start out with the Cab-O-Sil, mix to smooth slurry, add equal part of 
Micro, final should thick like shaving cream. Squeege on, and hard off, just 
leaving a fine film of epoxy (gloss), without any added thickness. Also can 
be used to thicken epoxy so doesn't run out of less than perfect joint, but 
doesn't take the place of flox. 

Date: Sun, 21 Feb 1999 09:28:31 -0600
From: David Domeier <david010@earthlink.net>
Subject: Re: COZY: Silica

Jeff and all,

    re "This is Cab-O-Sil.  Works with epoxy also.  Adds viscosity and
makes
it creamy."

    And it cures hard as a rock....I tried it to fill pin holes and it
was very difficult to sand.

dd

From: cdenk@ix.netcom.com
Date: Sun, 21 Feb 1999 09:51:10 -0600 (CST)
Subject: Re: COZY: Silica

DD said <And it cures hard as a rock....I tried it to fill pin holes and it
was very difficult to sand.>

Thats why I said just fill voids (pin holes), not for contouring. If you can 
see anything that looks like micro, you haven't pushed hard enough on the 
squeege.

