Ammonia helps make the balsa more plyable (bend easier) some say it can permanently weaken the wood.
I use warm water and just wipe it on with a rag and only when needed. 1/16" sheet balsa bends pretty easy. here is a project I am working on. The wing sheeting is 1/16" the fuselage is thicker at 3/32" and I had no problem installing the sheeting dry to spite the sharp curves on the nose of the fuselage and the landing gear fairings.