Treat inside of mandolin

[F Murtz]

do you varnish or oil finish the inside of a mandolin? (I was thinking of doing the bit where I want to stick some piezo pickups.)
Tried google with the same question and got no where,just commercial makers waffling about their finishes and the odd one telling how to finish the outside.

[Brian Evans]

While not mandolins, I put two coats of shellac on the inside of my archtop. Benedetto suggests it in his book.

[Mike Conner]

I just use waterborne poly on the inside of my archtop guitars and octave mandolins, a couple of coats:
- I'm guessing that it might help with longer term stability
- I only finish the sides and back, and not the inside of the front plate. Finish on the inside of the spruce would make for a big headache for any future repair of cracks!
- I use gel superglue to attach the piezo transducers to the raw wood on the inside of the front plate.
- While the second coat of finish is still tacky I can stick the labels to it.
- and... it just looks cool!
//mike