I think Balsarite (at least the film version) is also a good way to harden the balsa so that it doesn't ding so easily. I'm not sure what the difference between the thicker "fabric" and thinner "film" versions is--unless it is just the thickness. Clearly the fabric has an adhesive to stick things down, but I'm not sure if the film is chemically different or not.
added from Tower Hobby site:---note they claim it is good to use over fuel soaked wood!
Balsarite is a Clear Liquid that is used to Prep the Wood Surface Before
Applying Covering. Balsarite absorbs into the wood, waterproofing it,
strengthening it, and increasing the adhesion.
**NOT FOR USE ON MICAFILM**
FEATURES: This is for use with Film Coverings such as MonoKote, TowerKote,
EconoKote, UltraCote, 21st Century Film, Black Baron Film and
other similar coverings
Can be Applied to Fuel-Soaked Wood so that Covering can be Reapplied.