On a related note, Velo Orange is selling cork grips for upright bars that have been coated with orange shellac. They look like they're a pretty good match for Brooks honey saddles. That gave me the idea of trying to stain cork grips to match the antique brown B18 I bought my wife for Christmas. I have a bunch of cans of stain left over from my woodworking days. The closest match I have is some Pennsylvania cherry. I applied a coat of that last night. There's a lot of red in the antique brown, but the PA cherry is a bit too red. I think if I apply a coat of stain with more brown over it I'll be very close. I'll apply clear shellac once I'm happy with the color.
People keep talking about drying time between coats. That's really not much of an issue with shellac because the solvent is alcohol.
As for flexibility, I applied cloth tape over gel tape and then put down six coats of shellac. The shellac remains flexible enough after a year that there's been no cracking.