Epoxy Coating a Fretless Bass

Back in the early 1970s, Jaco Pastorius took the electric bass world by storm with his trademark fretless Fender Jazz Bass sound – and people have been chasing that sound for decades. Part of his unique bass tone came from a coating of Pettit Poly-Poxy (boat epoxy) that he applied to the fingerboard to protect it from roundwound string damage. It also turned out to enhance sustain and produce a brighter, snappier tone. Since then, this finishing method has been popular among fretless players, and has evolved and developed over time.

Today, two-part epoxy is popular due to it’s material hardness value when cured, and because it takes a polish beautifully. We’re sometimes asked to apply a deep-pour epoxy coating on a fretless bass fingerboard, which we do with the assistance of our Plek Machine. This not only provides the durability and the tone the player wants, it also ensures that the instrument plays perfectly and that all the notes up and down the neck speak clearly and evenly when it’s all done. There are many ways people approach this kind of job and many ways to get great results, so I’m going to show you the techniques that I’ve found have worked for me. Here we go!

The factory surface of a lined fretless Fender Custom Shop Jazz Bass.

First, I use the Plek machine to level the fingerboard. This way, I can end up with a perfectly even epoxy coating.

We do our fretwork using a surrogate body for easy truss rod access on heel-adjust bolt-on necks.

Once I level out the tiny cnc machining marks, I sand the rosewood to a 400-grit surface before applying the initial sealer coat. I then build a packing tape dam around the fingerboard.

I use clear packing tape because the adhesive side has practically no texture and makes the epoxy easier to work later.

We like System Three Mirrorcoat two-part epoxy. It cures glass-hard and crystal clear and has a nice, long open-time. The mixing ratio for this stuff is 2:1 resin to hardener. This must be exact for best results.

After pouring the epoxy pool, I run the drill press to vibrate the table and I hit the pool with a heat gun to drive all the air bubbles to the surface. If you use packing tape for this, be very careful not to melt it with the heat gun. Best to keep the gun moving.

Once the surface is level and clear of bubbles, I let it cure for several days before pulling the tape off.

I do the bulk material removal on the edge sander to cut a radius back into the playing surface, before putting it back into the Plek for the final surfacing.

I use the fingerboard planing function of the Plek to level the epoxy down to exactly 2mm thick all the way around the board with a perfect surface plane and radius.

The Plek makes it snow!
The machined surface.

I also use the Plek to cut a nut pocket into the new fingerboard surface.

Now, the post processing begins. I practice standard wet sanding and buffing techniques for this type of epoxy finish.

That’s what I’m talking about!

And here she is all strung up and setup!

New bone nut!

Turned out great! A very cool upgrade for a very cool bass. Now play us some Teen Town!

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