Different glues have different properties. Your best bet, might be to route the top off, being careful to stay inside the binding, and cutting only as deep as the top is thick at the edges. It's a tricky operation, but it can be done. Of course, you'll have to take off the fingerboard first, among other things. So if Prep Sol has acetone in it, you don't want it near a nitro finished guitar. It's made for dewaxing polyurethane car finishes. Denatured alcohol will remove Sharpie marker, but it also does a job on nitro unless you dilute it at least fifty fifty with water. Then it doesn't work so well on the marker ink. http://www.stewmac.com/ StewMac visited Mamie Minch and Chloe Swantner at Brooklyn Lutherie. Mamie shared this great tip for making scratches disappear, whil Completely remove all the old guitar finish; Upon removing all the hardware and the strings, the next thing to do is remove the old finish by sanding. But, if you don’t want to remove the old finish, simply rough it up and refinish the guitar. If you’re unable to decide, here’s what you need to do: Matte & Satin-Finished Guitars. A matte guitar finish should only ever be cleaned with a dry cloth. If you have ever owned a matte-finished guitar, you’ll know that over time the finish will wear down and shiny spots may start to develop where your hands have made the most contact with the instrument (such as above the bridge where your picking hand rests). What is my approach to oiling a natural finish guitar? Here's some of my tips. -T___Check out our awesome social media sites:•Facebook: Naptha also works extremely well removing masking tape residue from finishes. I use it sparingly on most any finish if a strong solvent is needed to remove stubborn stains. If there is any question about if a solvent is compatible with a finish, simply open a control cavity or the truss rod pocket, or the trem cavity, and rub some of the My guitar is a Blueridge with a Poly finish. Poly is very hard, which makes it difficult to remove scratches, and prone to swirls. I've seen some posts recommending auto finish swirl removers, and there was some mention of 3M products, but no specfics on which products, and how to apply them, and what type of applicator to use. xjTg.