ElfinSailor

I have been building model aircraft for a good many years and have come up with something that i have never experienced before. I don't usually use much Balsarite when building but did in a recent, yet unfinished project. I used some in the rudder fillets as per the kit producers recommendation in the instructions. After covering with silk and dope and proceeding on with finishing all of a sudden I discover that the filler has dissolved or more literally evaporated under the silk causing a lumpy saggy condition under the covering of the fillet.As I recall in the past I have no remembrance of this occurring. Can anybody explain to me what is causing this problem. It is a real pain as I am going to have to take giant back-steps to repair the situation.

TomCrump

If you used hobby type filler, or light weight spackle, Balsarite will disolve it.

ElfinSailor

Duuu I was using Hobby Lite not Balsa Rite as the filler. I covered it with silk and dope. years ago I never seemed to have a problem like I am experiencing now. I have subsequently routed out the affected area with a Dremel and filled it with a mix of West 410 Microlite and epoxy. I will most likely never use the Hobby Lite again as i am a silk and dope guy if I am not using glass and epoxy.Are there not two very similar products one called Hobby Lite and one called Balsa lite. The MicroLite and epoxy is an excellent filler but the sanding ratio between balsa wood and the epoxy makes it tough to achieve a smooth transition.

jaka

Hobby light filler is no good.
Use 24 hour epoxy and microballons instead!

ElfinSailor

@ JaKa if you like the phenolic microbaloons go to a marine supply and get some WEST Systems Microlite 410 you will find it is a vastly superior filler and fairing compound. Sands much more like balsa when mixed with a high ratio of filler to epoxy. Can be used with dope, aliphatic resin (white glue) or polyester resin.