Well I think that is the point - ammonia activates the adhesive by essentially dissolving it - then since ammonia is volatile it evaporates, allowing the solvent to dry/stick.

BTW, I used the windex method when putting some white checks on the wings of my red 4*60. Worked ok, but I found that I had to iron everything down the next day. So does the windex not work as well on oracover/ultracote?

I will also note that the 4* came with stick-on decals with very aggressive adhesive - the kind that usually stick where you don't want them to. Luckily, the instructions said to use Windex, which made placing the decals a cinch. It would have been nearly impossible to get those giant, long, skinny emblems on straight and bubble-free w/o the windex.