Looking at the Spector site I found out that basses before 2008 (mine is from '95) have to be cleaned with lemon oil...
"Use a pure lemon oil such as Forby's Penetrating Lemon Oil, to remove dirt, etc... You can also use this product on the maple parts (body, neck) and also the fingerboard to clean and humidify it."
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OIL FINISHES are never used on Rosewood/Ebony/Pau Ferro fingerboards. We were talking about what to use to clean the fingerboard and protect it.
Because Rosewood/Pau Ferro are very oily naturally, usually a light stain is applied. But never oil. It wouldn't take.
Ebony is stained because most Ebony that's available on the market isn't "solid black" anymore. It has color variations through it.
A maple fingerboard can be treated several ways. It can be covered in a gloss polyurethane, a matte polyurethane or can be oil finished.
Since Spector didn't start offering Maple fingberboards on basses until 2010, they will be gloss or matte poly. Not oil.
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The quote above from the website is for OIL finishes (BODY)... and it's simply to "CLEAN" the wood. Formby's, which is a product I've used before when trying to recondition dried out antique wood (because you never want to refinish it), is really a deep penetrating linseed oil with a lemon smell added to it. It reconditions and cleans.
Where is your bass from? Meaning, is it USA, Euro or Korean?
Oil based finishes were used more in the Brooklyn, Kramer (NS-2O) and SSD Eras. USA models mainly, some Euros... never on Korean models.
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There can be some confusion about Matte Finishes. Oil Finishes and Matte Finishes are often mixed up for one-another.
If your bass has a gloss finish, it's neither. It's a polyurethane gloss finish.