<br><font size=2 face="sans-serif">Tom</font>
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<br><font size=2 face="sans-serif">Sounds like Cab-O-Sil fumed silica. First off it is amorphous so no silicosis problems. It is quite different than microballons, as it does not increase volume or reduce the density of the "mix". It also does not affect the cured properties very much at all. Some will say that makes it , tougher, harder, or harder to sand etc. but you can only add about 6% by weight, so the properties of the epoxy are not really affected. It is hard to mix properly, because it really needs to be high shear mixed , which cannot be done with a stick. Poor mixing can weaken the epoxy and hurt the wet out properties, hence the real reason people percieve that it changes the properties. You can use it for corner fill in the mold, but you must be aware that you easily add 100-125 grams of dead weight to the plane. <br>
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Gray Fowler<br>
Principal Chemical Engineer<br>
Composites Engineering</font>
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<td><font size=1 face="sans-serif"><b>"Koenig, Tom" <Tom.Koenig@actewagl.com.au></b></font>
<br><font size=1 face="sans-serif">Sent by: discussion-request@nsrca.org</font>
<p><font size=1 face="sans-serif">05/18/2003 07:40 PM</font>
<br><font size=1 face="sans-serif">Please respond to discussion</font>
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<br><font size=1 face="sans-serif"> To: "'Discussion'" <discussion@nsrca.org></font>
<br><font size=1 face="sans-serif"> cc: </font>
<br><font size=1 face="sans-serif"> Subject: micro-balloons etc</font></table>
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Help.....please<br>
<br>
Gray, Matt, Lance.... anyone.<br>
<br>
I have a huge tub at home that is a white fluffy powder, which weighs<br>
nothing...( Nooooo....not that sort of powder<VBG>) I dont know wether it is<br>
micro balloons or cabosil, or whatever.<br>
When I mix it with epoxy it sort of forms the white stuff which you commonly<br>
see in the corners of layups ( to help lay the glass), but it isnt quite the<br>
same, it seems to be more translucent.<br>
Am I not mixing properly? It seems that when I keep adding more powder it<br>
becomes too dry and unworkable. It also doesn't seem that light which makes<br>
me think it isnt micro balloons. Is it the resin I'm using ( LC 3600)?<br>
<br>
Sorry for the moronic question...but how can I tell what I've got? Also what<br>
exactly is used as the fillers in the ZN kits, Bollys etc ? Do they use a<br>
thixotropic additive in the resin when they form the fillets etc.<br>
<br>
Thanks guys<br>
<br>
Tom<br>
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