Some use white or wood glue claiming it fills the balsa. Others have used the Brodak sanding sealers.
In the late 1960s Estes recommended Sanding Sealer. Centuri said to use Balsa Fillercoat. I used sanding sealer and occasionally balsa fillercoat. You can't find sanding sealer in hobby shops anymore. If you do find it, the cost seems prohibitive. Pactra and Midwest has discontinued their sanding sealers and balsa fillercoats. Brodak sealer seems to be out of production.
I've read about CA )Super Glues being used to seal and fill balsa grain. I've yet to use CA for this. I tend to fill the balsa wood grain off the model. A CA fill would seal the root edges preventing wood glue from soaking into the balsa, compromising the glue bond.
When I got back into the hobby in 2009, sanding sealer was difficult to find. Elmer's Fill N' Finish (now named Carpenter's Wood Filler or CWF) was the talk of the forums. I adopted this filler on my rocket builds.
In these two posts I took some scrap balsa and tried various methods to seal and fill balsa grain. This is not a complete test, I've not included the Brodak, Erockets sealer or CA methods. Papering fins is a discussion for another day.
Five pieces of balsa were tested. I tried to pick out wood pieces that had some consistent density and grain depth. After filling, all pieces will get white undercoats and a final red color.
The first piece (not shown here) will be raw balsa, no filler.
The second piece (not shown here) got a coat of wood glue and light sanding.
Third piece was raw balsa piece that only got one spray of Duplicolor Filler/Primer. After it dried it got a light sanding with 400 grit.
The fourth piece (not shown here) got one coat of brushed, thinned CWF and sanding.
This fifth balsa piece got a coat of thinned CWF and sanding.
This was followed by a spray of filler/primer and sanding.
Elmer's CWF is still my goto for filling balsa. I have also used wood or white glue, but mixed in talc to help with the filling and sanding properties.
ReplyDeleteHas anybody tried using gesso as suggested in kits from Custom Model Rockets?
ReplyDeleteHi Naoto,
DeleteI've never used Gesso. I'm pretty happy with the results I get now, I wouldn't want to go through another learning curve trying to get presentable results using another filler.
Aside from limited availability of stuff like sanding sealer, balsa fillercoat and model airplane dope, living in an apartment takes them off the table as you might have to avoid using anything with strong fumes to avoid getting complaints from your neighbors.
ReplyDeleteAside from that, there's the question of where one would use spraypaint when you live in an apartment. You'll need to get a ventilated spray booth if you've no other place than within your own unit. Finding a spray booth suitable for model rockets could be a challenge (since a larger model rocket would easily be larger than typical spray booth -- unless you go DIY route).