jwingnut1

Ok so I'm new to the hobby and I'm building my first kit. I see many applications for using microballons. While building the other day I came up with a crazy idea to use my balsa filler in my epoxy mix to make it more sandable and to give it a little "fluff". I seems to me that microballons are just some type of filler that accomplishes the same thing, but for added expense. I had no problem with the epoxy setting and it seems that sanding was easier. I realize that you give up some strength in lieu of the other properties. Is this a good Idea or should I just purchase some balloons? I've never used them before and am unsure about their properties.

SunDevilPilot

Just so you know, microballoons are just small glass spheres. I purchased a can of Sig Microballoons so long ago I can't remember purchasing it and it is still full after 4 airplane builds. Just get the can and it will last you forever.

Photo of microballoons below, in concrete.

R8893

My Feedback: (20)

Back in the "good old days" before microbaloons, balsa dust was sold for just that purpose.

tail strike

My Feedback: (1)

I make my own balsa dust koooof, kooooof.

DavidAgar

My Feedback: (108)

If your are talking about your balsa filler being some kind of putty, it is probally a water based product, which is not going to mix well with your epoxy. If you are in need of making a wing fillet then resin and micro ballons are recommended, however this should not be an every day filler. As for sanding, resin and micro ballons do sand, but no where near as well as balsa filling putty. Good Luck, Dave

Ed Smith

Be carefull with fillers applied to bare balsa. Any resin based filler will set up a lot harder than the surrounding balsa. When sanding the softer balsa will sand away leaving a blob of filler standing up and a real mess. You will not be able to feather the edges. Resin/Micro Ballon fillers should realy be used only on an already glassed surface that is hard.

Now this suggestion will probably bring a storm of criticism. The best filler I have found for use on bare balsa is drywall compound (Mud)?. It is very cheap and sands very easily. It must be used in moderation as the material is heavy.

The picture shows a wing tip block blended to the wing with drywall compound.

Ed S

Bad_Daddy

In the aerospace industry, we often use micro-spheres in our epoxy - especially when it is used to join 2 pieces of rigid material together. You see, the maximum joint shear strength is realized when the joint is .005 - .015 thick, so we use .005 - .008 micro-spheres in the mix to act like tiny "spacers" to keep the joint at the correct thickness.
BTW, micro-spheres are solid little marbles, micro-balloons are hollow little balloons.

BalsaBob

My Feedback: (24)

Jwingnut, A good reason to keep microballoons on hand is that they are compatable with pretty much everything you mix them with. You don't want to get yourself in a situation where you mixed balsa filler (for example) with something .... and then find out later (maybe much later) that they were not compatable and the bond is weakening or never totally curing.
As far as the cost of microballoons ... it is peanuts ,,,, you'll be surprised how long one bottle/jar lasts.
Enjoy building ! Bob

voyager_663rd

If you still end up using the m-balloons, make sure you don't stir them too hard when mixing. Do it gently because they will break and not do their job.