Hi Paladin,
I used Vallejo Liquid Mask since it's a hard edge demarcation and freehanded it with a flat brush, approximately, so it's not that exact but it's close enough :)
As for the hairspray method, this is the fourth time I am using it and it really is a tricky method, at least from my experience, because it's easy to overdo, but so far I like it as it looks very realistic. It depends on the HS thickness, base coat thickness, drying time, etc... I mentioned the other problem with significantly thinned down paint which I encountered. I had luck with my T34 with winter camo since it is a temp camo and a lot of it was chipped off, so the thicker HS layer worked fine. For everything else I would use thinner HS coat, especially at 1/72 scale. That's what I learned from my very limited experience :)
I haven't tried the pencil method and had no luck with sponge chipping, but will be persistant and learn that as well :)
Best,
Nikola