>>>>CA is a good hardener, but it isn't a filler. And as you note, it doesn't
sand worth a damn.<<<<
I would not suggest that CA is a good filler in an overall sense, but it does
have its uses for specific situations
And actually CA sands incredibly well. I have used it in spots where the balsa
surface not only needed to be very smooth, but hard so it could take somewhat
more abuse than normal. Like a shuttle orbiter nose made out of balsa.
Applying the CA can be tricky, takes some development of a knack for doing it.
The worst thing to use is fresh thin CA, it wants to "set off" into hard blobs
before it can be smoothed out. Thick CA is better. OLD CA is better still,
normally CA you do not want to use for building, but it's good to keep for this
kind of thing.
Unfortunately, applying CA over a relatively large area creates a lot of fumes
that can be overwhelming. So best of all is to use foam-friendly "odor-free"
CA, the thick type.
I apply the CA it with my fingers. Yeah, "eeew", but I've gotten used to CA
getting on my fingers and peeling it off later. For those not inclined to do
that, then try wrapping some plastic film over a finger, or using something
that CA does not bond to (this would be the kind of thing one might want to use
***gloves for, but the CA would stick to the latex).
After the CA is applied and has cured solid, when you sand it, start off with
something like 240 to 320 grit paper to get the high points off, so it is a
pretty uniform surface. Then go to 400 grit, and finish off with 600 grit.
Wet-sand when using the 400 grit and finer paper.
- George Gassaway