What is CABOSIL ??

[Gray E Fowler]

Mike

Neither cabosil nor microballoons are structural and they way you are 
using them is correct. Cabosil does not change the strength of the epoxy 
much at all and is used just to increase the thixotropic index -to make it 
not flow. 6% cabosil by weight when mechanically mixed will turn a low 
viscosity resin into jelly. Microballoons do reduce the strength of the 
epoxy but most of the time this is okay becuase it is still strong enough 
for our airplane applications. And as you know microballoons greatly 
increase volume and reduce the density of the epoxy. 



Gray Fowler
Principal Chemical Engineer
Composites Engineering




"Baiano, Mike [HCS]" <MBaiano2 at HCSUS.JNJ.com>
Sent by: discussion-request at nsrca.org
09/06/2002 11:08 AM
Please respond to discussion

 
        To:     "'discussion at nsrca.org'" <discussion at nsrca.org>
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        Subject:        RE: What is CABOSIL ??


HI Verne,
 
So does micro-balloon expoxy mixtures have any structural strength? I have 
both micro-balloons and cabosil - and I'm never quite sure when I should 
use one as opposed to the other. I generally reserve the cabosil when I 
just want to thicken epoxy into a paste, and weight isn't a huge issue. 
How do you decide which one to use for a particular application?
 
Thanks,
Mike
-----Original Message-----
From: Verne Koester [mailto:verne at twmi.rr.com] 
Sent: Thursday, September 05, 2002 11:41 PM
To: discussion at nsrca.org
Subject: Re: What is CABOSIL ??

Cabosil is fumed silica sand. It's extremely light weight. When mixed with 
epoxy finishing resin, it creates a paste that won't run on vertical 
surfaces. It's also frequently mixed with epoxy in a thinner mix and 
brushed into a mold to create the external gel coat on a glass part which 
prevents pinholes from making it to the surface of a part. On a clear 
epoxy-cloth piece, the epoxy/cabosil mix can be seen in all the 90-degree 
corners to bridge the radius the cloth can't make. It'll show as an opaque 
white as opposed to the clear epoxy/cloth you see everywhere else. Down 
side is that it's much tougher to sand than micro-balloons and has 
virtually no structural strength. Good stuff to have around, though. I use 
it a lot.
 
Verne
 
 
----- Original Message ----- 
From: Van - E-Mail LIST 
To: Pattern LIST 
Sent: Thursday, September 05, 2002 8:32 PM
Subject: What is CABOSIL ??

Don't think I know what this is ?
________________________________________________
 
Van Flowers
AMA: 6216 IMAC: 2229 
IMAA: 26019 NSRCA: 2778
www.rc-aerobatics.com
 
 
 
 

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