cabosil vs micro balloons
 

I just used cabosil for the first time after years of just using micro balloons mixed in epoxy for filler type applications. cabosil seems totally different. What are the advantages. It almost seems like it has a fibrous quality?

RE: cabosil vs micro balloons
 

Neither one has fibers so adds virtually nil for strength. Cab O Cil thickens better and will stay put better then micro ballons but the latter is easier to sand. Both will accellerate the epoxy cure. If you want a paste that will add strength use a mix of Cab o sil and milled fiber of flox. For the past 10 years I have not kept epoxy glue in the shop. I do lots of wet lay-ups with laminating resin, when I need an epoxy glue I just mix up some laminating, Cab o sil and milled fiber. Much stronger then epoxy alone.

RE: cabosil vs micro balloons
 

Well stated SRT,
I do the same thing. The only time I use MB is for leveling or dents and ding filling. Otherwise its West and cab.

RE: cabosil vs micro balloons
 

Interesting idea. Thanks. I do like West Systems and have some old stuff. But the 205 hardener has a limited shelf life for sure. The resin however seems to last forever.
Time to re-stock along with some cab!

RE: cabosil vs micro balloons
 

wrong thread.

RE: cabosil vs micro balloons
 

Make sure to use a micro particulate respirator with the cabosil. It is fluft silica. Very bad for lungs.

Hence the word Silicosis . Not user friendly.

Steve

RE: cabosil vs micro balloons
 

There are new formulas of "Bondo" [polyester type filler] that sand much easier than the original formula. If you limit the use of it to just feathering / blending rough FG work [like with smoothing male parts] the weight build up is not bad. It will make quick work of blending irregularities in balsa features too.

RE: cabosil vs micro balloons
 

I use heaps of both. It really depends on the application. If you are trying to reduce the specific gravity of the mix then MB (micro-ballons) is one of the few options. Adding cab-o-sil or milled fibers will increase the density of the resins (heavier per volume). You can add MB to lots of casting applications to reduce weight and require less resin. (the exotherm temps will go up as well). MB are one of the best volumizers because you can add lots of MB without greatly increasing the viscosity of the resin. I've added 3 times the volume of MB as the resin and still had is pourable. Fillets and skim coats (pin hole filling) can be made with MB and are much easier to sand and lighter than those that are made with Cab-o-sil. Often you can use both in a mix. MB added to resin will typically have a weaker tensile strength than just raw resin. In my experience, Cab-o-sil in moderate loadings doesn't weaken the resin. Very short milled glass fibers do very little to increase the strength....at least in the lab test results that we've done. To get a noticeable increase in strength you need to use longer fibers (1/8" or longer).

When I make a sploog for filling in tight spaces during molding layups, I use 3 equal parts of MB, cab-o-sil, and cotton flock. Cotton flock has a lower density than glass fibers. So if weight is an issue, I'll use cotton over milled glass. Add too much cotton flock and the mix will become hard to pipe in to the corners.

RE: cabosil vs micro balloons
 

Fine balsa saw dust mixed with West Systems epoxy works very well for certain applications where I'm looking for sandable fill in areas where polyester type fillers would dissolve the piece that I'm working with. This thin viscosity resin soaks into the sawdust nicely so you end up needing much less resin than anticipated.
I used to have a small tub of micro balloons that lasted me close to 25 years and now that it is gone...I could not care less.

RE: cabosil vs micro balloons
 

;) CABOSIL CELLS SANDS LIKE A BRICK!! MICRO BALLONS LEAVE MICRO HOLES WHEN SANDED.. TRICK IS "Q" CELLS..THERE LIKE SOLID MICRO BALLONS.. SAND LIKE BALSA.. ADD NO WEIGHT.. BEST SPOT FILLER IS ... "SPLIT SECOND" SUPER LIGHT...1/10 WEIGHT OF OTHER POLY TYPE FILLER.. SANDS WITH 320..NO STICKY TOP COAT.. AVAL. QUART CAN.. ;)

RE: cabosil vs micro balloons
 

Interesting. A Q-Cel distributor says:

"This material does not add strength instead it thickens the resin enabling the repairer to fill holes. Q-Cel glass micro cellular fillers are inert, inorganic, non-toxic, hollow glass particles whose shapes vary to combine different geometries . . . spherical and irregular. These shapes provide advantages as a filler-reinforcement. 4 ounces of resin filler/thickener."