| If the video you saw features JP playing the famed "Bass of Doom" then it is just a result of wear combined with the way the epoxy was applied, and the fact that Jaco didn't really take a white glove approach to caring for his basses after a certain point in his life.
That bass is also unusual because Jaco applied the marine epoxy with a brush, and it probably wasn't polished and/or buffed as a professional luthier would do. They say you could actually see the brush marks on the fingerboard of Jaco's bass.
These sort of finishes, when professionally applied, are buffed to a gloss and are very durable. There is wear to be had, but it usually occurs directly under the strings and not over the whole fingerboard. The rest of the board stays glossy.
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"I taught them everything they know, but not everything I know" - James Brown
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