Balsa Nose Cones

[AfterBurners]

The last one I had for my Bat Ray didn't turn out so great. Can any of you offer any suggestions for "properly" finishing (seal and sand) a balsa nose cone. I was considering just using Aero Gloss balsa filler. Apply a couple coats and sand and finish and then follow with sanding sealer until desired finish. Prime it and paint.

[Marc_G]

My current process:

1. Obtain nose cone from source that is likely to provide a good product needing relatively little fixing (SEMROC, BMS, Fliskits to name a few).
2. Very lightly and gently sand it to remove any roughness using a 3M sanding spong of grit around 220. VERY LIGHT TOUCH.
3. Using a Q-tip, rub thin CA over the entire cone surface (not the shoulder)
4. After an hour or so, use a 150 or 180 sanding sponge and go a bit harder over it to knock down the stuff that always stands up during CA treatment.
5. Use either Carpenter's Wood Filler (slightly diluted with water for spreadability) or 3 M / Bondo spot putty (I dilute with a few drops of lacquer thinner) and rub it into the grain. Let dry until product is fully dry/cured.
6. 180 grit sponge, sand till mostly smooth. CA treated balsa will be resiliant compared to the putty/filler so don't worry about hurting the cone too much. Then repeat with 220 sponge.
7. Rustoleum automotive filler primer. Heavy coat, then sand with 220 grit sponge.

Done.

Edit: use appropriate ventilation and personal protective equipment per directions of products listed.

[AfterBurners]

I did get the nose cone from SEMROC. 150 grit? Could you use 220? I would feel uncomfortable using 150

[Marc_G]

220 will be fine. But, after sealing with CA and giving it an hour to dry, it will be quite hard. I'm assuming in the garage or other warm semi-humid place; give it longer if cool or dry since CA uses humidity to set. Being in Indiana in the spring, it's kinda warm and humid here much of the time.

The key to the technique is that the balsa-CA composite material is very hard, whereas all the fillers (CWF or spot putty, and filler primer) are all VERY SOFT by comparison and you will quickly find the right amount of pressure to cut them without impacting the hardened, sealed wood.

Also, using a sanding sponge that can conform to the curved cone makes it much less likely that you will damage it. With say a flat sanding block, you might get a flat spot. But use of a sponge avoids that.

Marc

[AfterBurners]

thanks Marc I'll try it