If you use Ca on hardwood, always rub a little soda (like your wife uses in the kitchen) on the area to be glued before gluing it as hardwoods tend to be acidic which CA does not like to work with. The soda neutralizes the acid and lets the CA perform at full strength. Yes, I know that balsa is a hardwood but it does not seem to be nearly as acidic as oak, spruce, pine etc. are so does not require the soda. However, soda even improves the bond with balsa. You will find soda to be a real asset when using CA. You can even fill a hole with soda, apply thin CA, and drill and retap the hole for a metal screw.