The Good Book Verses on an old guitar by ricfreak Singapore, The Acoustic Guitar Forum – Sealing Sharpie art on guitar ??? BIL SAYS: One approach is to use very light coats of lacquer sprayed on OR polyurethane depending on the original finish. Build up with 6-8 coats with very fine sanding between each coat. Can be wet n dry rubbing. Then finish off with auto polish.