Occasionally a guitar part shows up that I genuinely don't have listed on any spec lists for any projects, and I don't remember ordering it. This is what happened with this neck I decided to do a heavy flame relic to. Think what you want about relicing guitars, it sure is a fun process for the builder.
Turned out pretty nice. Finished with a little boiled linseed oil. If there's any "trick" to torching with this little stripe-effect down the side of the neck it would be to first sand off almost all of the finish, leaving a thicker area where you want the striping down the neck. When you go to torch the neck, it will darken right up to the edge where the finish starts. Be advised, it will crackle, but if done right, it can yield a very cool burnt sienna coloration. Sanding down the transition area between the satin finish neck and the roasted finish is really important. It's a balance of sanding it down until its completely comfortable without losing the visual effect.
Here I've aged the fretboard with turmeric, after scraping an obscene amount of finish of with a razor. I have a lot of tricks when aging necks. One of my favorites that is pictured in one of the above photos is as follows: Save your old used tea bags. When you take the finish off of a neck or body and want to add some age, tape up the tea bag so you can make a little blotter with it. You can use this blotter with tobacco brown leather dye, or brown permanent stamp ink to create discoloration and the illusion of age. Dab a little turmeric on your tea bag and you have a really strong and really vintage-looking tool with which to add age to guitars.