What is CABOSIL ??

[David Harmon]

Gray...does Hobbypoxy #3 Thixotropic epoxy have cabosil in it or does it
have some other substance
that makes it so thick?
    Dave

-----Original Message-----
From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org]
On Behalf Of Gray E Fowler
Sent: Friday, September 06, 2002 9:37 AM
To: discussion at nsrca.org
Subject: RE: What is CABOSIL ??



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> 
        cc:         
        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:  <mailto:extra330 at tampabay.rr.com> Van - E-Mail LIST 
To:  <mailto:discussion at nsrca.org> 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
 <http://www.rc-aerobatics.com/> www.rc-aerobatics.com 
  
  
  
  



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