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Old Feb 03, 2006, 11:04 AM
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Santiago, Chile
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How to use microballons on foam?

hi, I want to paint my formosa so I will be applying some microballoons topflite filler on to it, then sand it and finally paint with acrylic paint. But according to towerhobbies¨s description it has to be mixed with epoxy, but I dont want it to be heavier so can I put it on just like it comes from the bottle?

has anyone done this to his GWS airplane?
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Old Feb 03, 2006, 11:33 AM
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Louisville KY
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I don't think it's necessary. I sanded my Pico TM with 180 grit garnet sandpaper and it cut the foam very nicely. Garnet has sharper and more brittle edges then aluminum oxide or other papers. It doesn't last any way near as long as other papers so a lot of people don't use it but on foam it's a big advantage. People use it for exceptional finishes on wood too.
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Old Feb 03, 2006, 04:08 PM
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You can't put microballoons on by itself because it's just a powder-like substance and won't stick to the foam. It's used with epoxy to make a lighter-weight glue than just straight epoxy - it also sands more easily than plain epoxy.

As for sanding, I've had great luck using drywall sanding screens on foam - the kind that looks like screen door material, but with abrasive on it. It doesn't seem to chunk-out the foam as much as regular sandpaper. Never tried the garnet variety on foam, though - maybe it's even better? BTW drywall screens also work great for sanding plastic without making it fuzzy.
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Old Feb 03, 2006, 05:43 PM
SEC
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I'm planning on using acrylic paint on the e-starter I've just started. Sanding first with a drywall screen, then a coat of drywall spackling paist, sanding lightly again after its dry, has given a nice finish to a few test pieces, and doesn't add much weight. I found a water based clear coat at Home Depot, that's been safe with the test pieces as well, that gives a nice finish.
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Old Feb 03, 2006, 05:53 PM
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United States, CA, Garden Grove
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I think that you could mix micro-balloons with water based latex like Min-Wax Polycrylic clear. It would be lots lighter than resin and would sand away much easier. I used Polycrylic to glass the ailerons on my GWS Zero. You should be able to glass the whole model with Polycrylic and 1/2 ounce fibreglass cloth or even silkspan. I painted my Zero with a Badger siphon type air brush using water thinned craft store acrylic. Just go easy on paint especially toward the rear. If you mount lipos and other as far forward as possible, you may not have to add as much or any nose weight.

Others have used low temp iron on coverings, probably lighter and much easier if done right.
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Old Feb 04, 2006, 03:43 PM
ncb
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If you do try using micro balloons make sure you wear a good respirator. The balloons are so small they blow every where and they are not good for your lungs.
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Old Feb 04, 2006, 07:45 PM
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Nevada City, California, United States
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one other thing to know about using balloons in epoxy. when you add them the epoxy cooks off much faster. i use 30 minute epoxy when i use balloons and it cooks off in just 5-7 minutes. i never tried 5 minute epoxy, i'd expect it would cook off so fast as to be unusable.
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Old Feb 04, 2006, 09:06 PM
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Drywall putty works good too, and it's lightweight.
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Old Feb 05, 2006, 12:22 AM
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Quote:
Originally Posted by Catkicker
one other thing to know about using balloons in epoxy. when you add them the epoxy cooks off much faster. i use 30 minute epoxy when i use balloons and it cooks off in just 5-7 minutes. i never tried 5 minute epoxy, i'd expect it would cook off so fast as to be unusable.
Hmm thats odd as all I use micro balloons in is 5 minute epoxy and it doesn't effect the time it takes to cure at all, I don't know how it could even since it is cured by a chemical reaction and micro ballons are nothing but small glass balls. Maybe a different brand has something else mixed in with it? I use the white ones.
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Old Feb 05, 2006, 02:50 AM
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grain valley mo, or about 25 minutes east of kansas city
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Quote:
Originally Posted by Steve H.
Hmm thats odd as all I use micro balloons in is 5 minute epoxy and it doesn't effect the time it takes to cure at all, I don't know how it could even since it is cured by a chemical reaction and micro ballons are nothing but small glass balls. Maybe a different brand has something else mixed in with it? I use the white ones.
it has to do with how much you mix at one time. the more you mix the quicker the epoxy cooks no matter what minute epoxy you use, when you mix in the micro balloons it keeps the heat from escapeing as fast and so the epoxy sets up faster in you cup. works better to mix it on a flat surface if you don't want it to cook quicker.

btw, microballoons are interesting to use with some ca glues. one in particular allowed me to mix the ca with the balloons and then spread it out on the surface and then it kicked like accelerater had been sprayed on it. it was a strange delayed reaction. sanded great, works well on fiberglass.


Jason
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Old May 10, 2009, 06:51 PM
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Shelbyville, KY
Joined Apr 2009
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Microballoons and 30 minute epoxy

Guys,

I've been trying to use Microballoons and 30 minute epoxy to do a fillet. I'm new to it and I don't understand why mine won't sand easily like I've read on the forums.

I've tried using more Microballons but the finished product is still to hard to sand. What am I doing wrong. I am going to try CA.

Ken Antos
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Old May 10, 2009, 07:48 PM
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I mix my Micro-ballons with a white glue, makes sanding them easier. Also, the white glue is lighter then epoxy.
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Old May 11, 2009, 03:48 AM
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Microballoons and white glue

Thank you very much! Very logical and simple
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Old Oct 03, 2009, 03:42 PM
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Dallas, TX
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Just ran across this thread so it is probably way too late, but thought I would offer my 2 cents.

Suggest you try finishing resin. Dose not have the hardener (can't remember the name of it) that normal fiberglass resin has in it. When first got my hands on micro balloons back in the late 70s, that is what was recommended. Have not used them since early 80s as I got out for quite a few years.

Ron
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Old Oct 03, 2009, 05:14 PM
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Finishing resin

Ron,

Thanks, I tried regular 30 min epoxie, then I found out about Finishing Resin. I needed some anyway to use with fiberglass cloth.

I use quite about of microballons in it and that worked pretty well. Then what I did was used balsa filler to make sure everything was smooth and looked the way I wanted it to. Then I took just the resin and hardner and painted a thin coat on top of the balsa filler. Then covered it with monokote. Came out very well, but of course we always want the monokote to come out looking perfect with NO wrinkles, but it never does.

Thanks a bunch for your reply.

Ken
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