From: "Hunter GA (Gary) at MSXSCC" 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" 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 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 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 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.