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Micro-balloons are a component of stira-foam. As the previous noter
indicated, you can mix them with the clue of your choice to produce
a filler. However, I would NEVER use such filler. When mixed with
epoxy, the stuff is as tuff as bullets, and consequently, VERY difficult
to sand. When used to fill balsa, the results are nothing short of
TERRIBLE. Why don't you try Micro-Fill by Northeast aerodynamics, or
[I believe] Magic-Fill. This stuff is a white material with a "fluffy"
consistency. It dries "stiff" and is a "joy" to sand... sands just like
balsa. Once you try it, you'll never anything but.
A word of caution... DO NOT use micro-balloons and Epoxy on balsa!
Good luck,
Brian
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| Microballoons are tiny beads of glass, so fine that they look and
handle like powder. They are used as a thickening agent in
fiberglass resin, such as when mixing a gel coat, and for general
useage as a filler. The spackling compound consists of an
base material, acrylic, I believe, similar to very thick white
paint, with microballoons (blast it, I cannot spell that word!)
to take it to the consistency of a filler.
I like to take the mixture and thin it with water back down to a
thick liquid, then apply it over bare balsa with an artist's
knife. When sanded, it produces a very smooth surface for paint.
The spackling is cheap. I'm still working off a can of Model
Magic filler that I paid 3-something for, before I opened the can
and found out what it really was.
One of those miracles of modern life...we used to use cornstarch
in dope. Very heady to say the least.
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| As John already explained, micro-balloons are extremely fine beads
of actual glass, not styrofoam. As Brian [I think} mentioned, if
not mixed properly, especially with epoxy, the stuff can be miserable
to sand but, like nearly everything else, if properly used in the
right applications, micro-balloons are a real godsend!
The first thing to bear in mins is that, unless you intend to use
the mixture internally [where no sanding will ne required], do not
mix balloons with epoxy adhesives, i.e. 5-min, 30-min. epoxy, etc.
Balloons should only be mixed with polyester or epoxy resins if
the mixture is to be used externally and sanding will be required.
I like to use polyester-resin/balloons for such things as small
fillets around stab and rudder, fairing in canopies, building up
fairing panels etc. I mix the stuff "extremely" dry; lots of balloons
to just a little resin and the stuff sands very easily, can be carved
with a knife or shaped with a file. BTW, mix the resin/balloons
"BEFORE" adding the catylist...then, as you need it, take a little
of the mixture and catylize with the smallest single drop you can
manage and apply to the intended area. smoothing it with a dampened
finger or equivalent. On the MiG-3, the panel fairings around the
stab-to-fuse juncture, the gun tunnels and the canopy framing adjacent
to the fuse are all done with balloons and the effect is quite realistic.
I don't recommend balloons as a balsa filler though I know of some
modelers who use it this way and swear by it. My buddy, Ted White,
applies .6-oz. glass cloth [Dan Parsons', of course] with K&B clear
epoxy, then after a second coat of clear, he applies a slurry of
K&B epoxy primer and micro-balloons. After sanding the slurry down
nearly all the way to the cloth, he's ready to paint. I may try
this technique myself but, `til I do, I can't honestly recommend
it.
Adios, Al
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| Microballoons are also an incredibly fast strength-filleting system.
Finger-pack DRY microballoons into the joint, smoothing them with
your finger. Then get back a bit and hit the joint with a drop
or two of CA glue. The glue will "hit" almost instantly, and you
have a very strong (but mildly ugly) fillet.
Microballoons are a lot lighter to use than _my_ moral equivalent,
Baking Soda!
(I thought microballoons were hollow, not solid beads ?? Anybody
got a microscope and a hammer? )
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