How to sand an over-oiled guitar top?

[Manuel Bonilla Beya guitars]

Hi Alex.

I’ve been asked to put some nitro or poly finish on an oiled (lindseed) maple fingerboard. Maybe Doug could tell us if shellac would be a good choice for a base coat without needing to remove the oils. At least that’s what I think I could do: cleaning first with some degreasing solvent and then building a base layer with shellac before applying nitro.

[Alex Q Guitarworks]

Hey there!

I managed to start the job today, in fact the pessimism I had has been confirmed as the top has so much oil into it that is basically soft to the touch, and you can heavily scratch it with the nail. I understand why the owner wanted it coated.

Second I was able to remove the first ‘layer’ of oil with heavy aggressive sandpaper then, as you suggested, using a degreasing solvent. It is still oiled in deep but my local ICA salesman pointed me at a product to spray before the sealer that basically act as a barrier that doesn’t allow the subsequent coat of paint to interfere with wathever is into the wood.

[Ian Davlin The Looth Group]

Removing a finish like this try a scraper instead of sanding.

[Alex Q Guitarworks]

I tried but the finest of the scraper wanted to dig into the top very easily as is too soft

[Dave Staudte (rhymms with "Howdy") NB Guitar Repair (New Braunfels, TX)]

Is this an electric or acoustic guitar?

[Alex Q Guitarworks]

Electric. He started the build but cannot complete it. Actually don’t know why the top has been oiled, probably he just wanted to see how it looked like once completed

[Dave Staudte (rhymms with "Howdy") NB Guitar Repair (New Braunfels, TX)]

Well, there’s only one thing I can think of. Simtec makes a product called Hot Pot. It’s a 2 part catalyzed sealer that you use MEK to activate. It in effect creates a plastic like sealer. You might want to contact them and inquire about your situation. It is used as a barrier over troublesome woods.