The epoxy that Jaco used on his fingerboards, “Poly Poxy” was made by Petit Paints, a manufacturer and distributor of materials specifically designed and marketed to the boating industry. Jaco chose to use this particular marine-grade epoxy because it was extremely durable and readily available around Fort Lauderdale, where he was living at the time that he decided to convert his bass to fretless.
It is my understanding that he opted to use the epoxy coating primarily to extend the life of the fingerboard. He used round wound strings and played/practiced almost ceaselessly. Left unprotected, a rosewood fingerboard would have become so worn as to become unplayable in short order.
As to the cosmetic qualities of the Poly Poxy, rather than enhance or otherwise highlight the grain of the wood or other material that it covers, this particular product simply darkens the entire surface slightly. It also has a rather peculiar and slightly greenish tint that is most readily observed when covering a white or light colored surface. On the Bass Of Doom, this greenish tint was visible on the clay position dots and light colored fillers in the vacated fret slots. I referred to this tint as “baby poop green” and found it to be only moderately hideous in appearance. I’ve never seen it used on a maple fingerboard, but would imagine that the visual effect would be even a bit more hideous, but that’s just my taste. You might like it.
