Quoted from Gruntis:Nah nothing that involved but my method could be considered a little controversial. I used a $16 pack of textas. Have to use a tissue to wipe over it when done to remove the stroke marks. If done right you can't tell and because it's somewhat transparent it allows the shading to come through. Not sure how well it will hold up over time but looks great IMO.
Certainly not the best method but definitely the cheapest. Took a few hours to do both sides.
Sorry for the ignorance, but what the heck are Textas??
PS Your touch up looks fabulous!